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New Walk in Cooler charging way !
|
|
| TURTLE 2005-10-09, 1:21 am |
| This is Turtle.
I was installing 2 new walk-in R-22 type coolers condensers and found a
card attached to the head master valve which told me to charge the
condeners this away. I will type the whole card and what it said about
charging the New Copland Cooler condensers about 10K btu size. It does
have the by-pass valve on it for cold weather.
Here is what the Copland Card said !
==========================================================
" FLOODED " SYSTEM CHARGING/START-UP PROCEDURE
1. Charge with appropriate refrigerant until sight glass is clear.
Operating conditions must be stable, with air intake blocked, as
necessary, to maintain a minimum 200 psig head pressure so no gas will
bypass through the flood valve. [DO NOT OVERCHARGE]
2. WEIGHIN additional charge necessary to blockflood the condenser
during winter conditiuons. The amount for this unit is 3.8 lbs.
NOTE See instructions in control box for detailed starting and
operating procedures.
FORM # 110213-015
==================================================
Here is one for you and it works with weighing in a the charge and run
like a charm. Around here we rarely get to install new copland stuff
but how long have the been doing this ?
TURTLE
P.S. I'm kind of bussey now and may not reply too soon to this after
about 2 hours or so.
| |
| Power's Mechanical 2005-10-09, 12:21 pm |
| Here is one for you and it works with weighing in a the charge and run
like a charm. Around here we rarely get to install new copland stuff
but how long have the been doing this ?
TURTLE
P.S. I'm kind of bussey now and may not reply too soon to this after
about 2 hours or so.
xxxx
You probably didnt have to put the whole 3.8 lbs in. Im sure it
depends on the lowest expected ambient temperature and the 3.8 is
probably for the worst case.
The by pass valve you refer to is correctly called a head master and I
dont expect you see as many in warmer climates as we do up north. The
chargeing method you described has been the standard way except you
calculate the amount of additional refrigerant depending on the lowest
expected ambient temperature and coil size. The goal is to flood
approx. 70% of the condenser. The by-passed hot gas is used to warm up
the reciever and help control flash gas.
Normally the system is charged until the SG is full and at that time it
has the correct amount of refrigerant for the ambient at the time, then
you add the extra refrigerant calculated according to tables in the
installation instructions. I think the instructions you read are over
simplified.
If you didnt need the full 3.8#s youll find out next summer.
| |
| TURTLE 2005-10-09, 2:21 pm |
| This is Turtle.
Yes I did refer to the Head Master valve as the Head Master Valve but
down here we don't call it that and refre to it as a Condender by-pass
valve. Head Master sounds like the head fellow running a whore house.
I call the warehouse about this 3.8 pounds and they said do what the
instruction [ all the instructions ] said. No question ask.
If I have trouble next summer , I will cut the HEAD master out and put
a fan control on the condenser fan and for get about it.
I guess these type cooler condensers are for very cold weather and just
sometime we see them.
TURTLE
| |
| ..p.jm@see_my_sig_for_address.com 2005-10-09, 2:21 pm |
| On 9 Oct 2005 09:47:03 -0700, "TURTLE" <hvacturtle@gmail.com> wrote:
>This is Turtle.
>
>Yes I did refer to the Head Master valve as the Head Master Valve but
>down here we don't call it that and refre to it as a Condender by-pass
>valve. Head Master sounds like the head fellow running a whore house.
Gee, some people would relate the title 'Head Master' to 'the
man in charge of a school', if anything, not a whore house. To each
based on his background, I guess.
>
>I call the warehouse about this 3.8 pounds and they said do what the
>instruction [ all the instructions ] said. No question ask.
>
>If I have trouble next summer , I will cut the HEAD master out and put
>a fan control on the condenser fan and for get about it.
More hack bullshit, just like always, and you're pathetic for
even THINKING about it.
Here's a little hint for you - you do NOT know more about the
design of that unit than the engineers who designed it, and you are
NOT capable of improving their design, and you do NOT 'just rip out'
any parts you don't understand.
Unless you're a weasel back-woods hack-without-a-clue.
>
>I guess these type cooler condensers are for very cold weather and just
>sometime we see them.
>
>TURTLE
Click here every day to feed an animal that needs you today !!!
http://www.theanimalrescuesite.com/
Paul ( pjm @ pobox . com ) - remove spaces to email me
'Some days, it's just not worth chewing through the restraints.'
'With sufficient thrust, pigs fly just fine.'
HVAC/R program for Palm PDA's
Free demo now available online http://pmilligan.net/palm/
| |
| TURTLE 2005-10-09, 4:21 pm |
| This is Turtle.
You Poor Devil , you still think you are listen to with any respect !
TURTLE
| |
| ..p.jm@see_my_sig_for_address.com 2005-10-09, 4:21 pm |
| On 9 Oct 2005 12:11:44 -0700, "TURTLE" <hvacturtle@gmail.com> wrote:
>This is Turtle.
>
>You Poor Devil , you still think you are listen to with any respect !
>
>TURTLE
I KNOW it, you pathetic hack, and so do you.
Now, for your afternoon entertainment, go find a piece of
equipment, hack-saw out all the components you don't understand, and
then throw acid on what's left and sand it down.
Then charge the customer your usual Sunday call-out rate, $ 15
/ hour.
IOW - no, I'm STILL not about to tolerate your hack bullshit
here. Take a hint.
Click here every day to feed an animal that needs you today !!!
http://www.theanimalrescuesite.com/
Paul ( pjm @ pobox . com ) - remove spaces to email me
'Some days, it's just not worth chewing through the restraints.'
'With sufficient thrust, pigs fly just fine.'
HVAC/R program for Palm PDA's
Free demo now available online http://pmilligan.net/palm/
| |
| Power's Mechanical 2005-10-09, 11:21 pm |
| This is Turtle.
Yes I did refer to the Head Master valve as the Head Master Valve but
down here we don't call it that and refre to it as a Condender by-pass
valve. Head Master sounds like the head fellow running a whore house.
> I thought head masters were school teachers..
I call the warehouse about this 3.8 pounds and they said do what the
instruction [ all the instructions ] said. No question ask.
>Yeah. They dont know any better either.
If I have trouble next summer , I will cut the HEAD master out and put
a fan control on the condenser fan and for get about it.
>Wouldnt it be easier to remove a little refrigerant if you have to? WTF would you "cut it out"?
I guess these type cooler condensers are for very cold weather and just
sometime we see them.
>They (the instructions) are probably averaged out for a zero degree ambient so the 3.8 is way too much for your area. You could probaly get by with a P 66 or a fan cycle control. I can see you using a fan cycle control because its as simple as it gets.
Bottom line is this "new way" of charging has been around since Christ
was beating Richs XXX and its not as cut and dried as you think it is.
TURTLE
| |
| Cooltemp Industries 2005-10-10, 12:21 am |
| "TURTLE" <hvacturtle@gmail.com> wrote in news:1128885104.535224.263910
@o13g2000cwo.googlegroups.com:
> This is Turtle.
>
> You Poor Devil , you still think you are listen to with any respect !
>
> TURTLE
>
The person who "are listen to" with respect certainly isn't you, especially
after you just confirmed what this Paul guy has been saying about you all
this time.
You are clueless.
| |
| TURTLE 2005-10-10, 12:21 pm |
|
<..p.jm@see_my_sig_for_address.com> wrote in message
news:ktqik19ecq1i1ktqku3jk85akgh258ggpq@4ax.com...
> On 9 Oct 2005 12:11:44 -0700, "TURTLE" <hvacturtle@gmail.com> wrote:
>
>
> I KNOW it, you pathetic hack, and so do you.
>
> Now, for your afternoon entertainment, go find a piece of
> equipment, hack-saw out all the components you don't understand, and
> then throw acid on what's left and sand it down.
>
> Then charge the customer your usual Sunday call-out rate, $ 15
> / hour.
>
> IOW - no, I'm STILL not about to tolerate your hack bullshit
> here. Take a hint.
>
This is Turtle.
Still Your swilling about being the big man here but Pie Face nobody give a
rat's XXX what ytou have to say. Also your PBBS team is getting so sorry that i
feel very little need to respond to your stupid rant than your just another
troll on the newsgroup. I think i may change your name to Troll Paul in the
place of Pie Face.
OH Yea, You need to get out of your trailor and get a job to make a living and
stop tring to sell that trash your selling over the internet. Hey one ideal here
if you make less than $300.00 a month you can get food stamps for you and the
cats.
TURTLE
| |
| TURTLE 2005-10-10, 1:21 pm |
|
"Cooltemp Industries >" <gbroderick@sunlife.com> wrote in message
news:Xns96EAE50D91564gbrodericksunlifecom@216.196.97.142...
> "TURTLE" <hvacturtle@gmail.com> wrote in news:1128885104.535224.263910
> @o13g2000cwo.googlegroups.com:
>
>
> The person who "are listen to" with respect certainly isn't you, especially
> after you just confirmed what this Paul guy has been saying about you all
> this time.
> You are clueless.
This is Turtle
Glad to see a few poor devils tring to support this looser but hey Cool i don't
care what is said about me as long as this stupid XXX hole Troll Paul is going
with me and his software sales too. Paul Trolling like this sure helps his
software sales. I would think you has not got a hit last week at all.
One Sad thing here is Paul Troll is a looser and does not know it.
TURTLE
| |
| Geoman1 2005-10-10, 4:21 pm |
|
Turtle,
The head master control sees outlet head pressures, and when the system goes
below a determined pressure it allows condenser hot gas to bypass directly
into the reciever. Being in N Orleans area I doubt if it will work that
often, it is a low ambient type control.
The reason to cover the condenser is to get up to 200 PSI, in weather up to
75 degrees you can usually charge the system to a full sight glass and then
add the extra gas.
Now, we use to have to compute the extra amount of gas by determining the
lowest ambient temperture the unit will be installed. Just for an example,
if you go down to 40 F you may need and extra two pounds but for a -20 area
it may take over four pounds to create a flooded condenser. ON very large
systems this amount can be substantial at times.
If you have a problem in your area during a very very VERY hot summer you
may have to remove some of the gas due to an overcharged condition. However,
I would think Copeland sized their system to be able to even work In Vickies
back yard, so I don't think you will have any problems. The problems arise
when the installer doesn't use a large enough reciever. I never used the
Copeland unit but Russel / Heatcraft are basicly the same.
Years ago we had to add an extra reciever or special order a larger one to
accomodate low ambient controls.
Sporlan.com has GREAT information concerning these controls. We in the north
use them every day due to low outside temps.
Rich
| |
|
| Geoman1 wrote:
> Turtle,
>
> The head master control sees outlet head pressures, and when the system goes
> below a determined pressure it allows condenser hot gas to bypass directly
> into the reciever. Being in N Orleans area I doubt if it will work that
> often, it is a low ambient type control.
>
> The reason to cover the condenser is to get up to 200 PSI, in weather up to
> 75 degrees you can usually charge the system to a full sight glass and then
> add the extra gas.
>
Curious, Rich....
When I installed the larger compressor on the Hankison setup this
summer, the OEM had me setting the 'Hot Gas Bypass' to get the suction
pressure up.... if I remember correctly now (-;.
This valve modulates, and does exactly what you say it does (in this
case), but I'm wondering why a adjustment might have been necessary in
what was essentially a high condenser inlet air situation?
This unit has two receivers, as I recall....
Jake
| |
| ..p.jm@see_my_sig_for_address.com 2005-10-10, 8:21 pm |
| On Mon, 10 Oct 2005 22:57:55 GMT, Jake <jkelleyus@insightbb.com>
wrote:
>Geoman1 wrote:
>
>
>Curious, Rich....
>
>When I installed the larger compressor on the Hankison setup this
>summer, the OEM had me setting the 'Hot Gas Bypass' to get the suction
>pressure up.... if I remember correctly now (-;.
>
>This valve modulates, and does exactly what you say it does (in this
>case), but I'm wondering why a adjustment might have been necessary in
>what was essentially a high condenser inlet air situation?
Low load.
>
>This unit has two receivers, as I recall....
>
>Jake
Click here every day to feed an animal that needs you today !!!
http://www.theanimalrescuesite.com/
Paul ( pjm @ pobox . com ) - remove spaces to email me
'Some days, it's just not worth chewing through the restraints.'
'With sufficient thrust, pigs fly just fine.'
HVAC/R program for Palm PDA's
Free demo now available online http://pmilligan.net/palm/
| |
|
|
>
>
> Low load.
OK, I'm trying to understand this. Do you mean low condenser load? Or
low HX load?
High condenser inlet temps would possibly load the condenser to a point
where it is no longer able to condense 100% liquid? So the hot gas is
being dumped into the receiver by the hot gas bypass?
Why would this get your suction pressure up vs. just sending all to the
HX and then to the receiver? Or was I going the other way and sending
less hot gas direct to the receiver and more through the HX?
OK, newbie questions (-;, I know! Fire away!
Jake
| |
| ..p.jm@see_my_sig_for_address.com 2005-10-10, 10:21 pm |
| On Tue, 11 Oct 2005 00:26:22 GMT, Jake <jkelleyus@insightbb.com>
wrote:
>
>
>OK, I'm trying to understand this. Do you mean low condenser load? Or
>low HX load?
Low Supply side load ( evap, I'll refrain from using the term
'HX", because it's non-informative as to what side of the system is
being referred to ).
If I recall, your drier was using it as a low load control,
rather than low ambient, injecting hot gas into the evap to keep the
back pressure up, rather than bypassing the condensor to keep the high
side presure up.
IOW - when there is no or low call for compressed air, back
pressure would want to drop, and ice. HGB would keep the pressure up
to avoid that.
>High condenser inlet temps would possibly load the condenser to a point
>where it is no longer able to condense 100% liquid? So the hot gas is
>being dumped into the receiver by the hot gas bypass?
Hopefully no to the first, and the second would certainly not
be an answer to that issue.
>Why would this get your suction pressure up vs. just sending all to the
>HX and then to the receiver? Or was I going the other way and sending
>less hot gas direct to the receiver and more through the HX?
>
>OK, newbie questions (-;, I know! Fire away!
>
>Jake
>
>
>
>
Click here every day to feed an animal that needs you today !!!
http://www.theanimalrescuesite.com/
Paul ( pjm @ pobox . com ) - remove spaces to email me
'Some days, it's just not worth chewing through the restraints.'
'With sufficient thrust, pigs fly just fine.'
HVAC/R program for Palm PDA's
Free demo now available online http://pmilligan.net/palm/
| |
| TURTLE 2005-10-10, 11:21 pm |
|
"Geoman1" <Geo1> wrote in message news:ScudnUx7UaSyKNfeRVn-pw@adelphia.com...
>
> Turtle,
>
> The head master control sees outlet head pressures, and when the system goes
> below a determined pressure it allows condenser hot gas to bypass directly
> into the reciever. Being in N Orleans area I doubt if it will work that often,
> it is a low ambient type control.
>
> The reason to cover the condenser is to get up to 200 PSI, in weather up to 75
> degrees you can usually charge the system to a full sight glass and then add
> the extra gas.
>
> Now, we use to have to compute the extra amount of gas by determining the
> lowest ambient temperture the unit will be installed. Just for an example, if
> you go down to 40 F you may need and extra two pounds but for a -20 area it
> may take over four pounds to create a flooded condenser. ON very large
> systems this amount can be substantial at times.
>
> If you have a problem in your area during a very very VERY hot summer you may
> have to remove some of the gas due to an overcharged condition. However, I
> would think Copeland sized their system to be able to even work In Vickies
> back yard, so I don't think you will have any problems. The problems arise
> when the installer doesn't use a large enough reciever. I never used the
> Copeland unit but Russel / Heatcraft are basicly the same.
>
> Years ago we had to add an extra reciever or special order a larger one to
> accomodate low ambient controls.
>
>
> Sporlan.com has GREAT information concerning these controls. We in the north
> use them every day due to low outside temps.
>
> Rich
>
This is Turtle.
I called back today to talk to the warehouse which got in touch with the copland
rep. and the freon pounds to added is calculated for my area and the amount of
freon 3.8 pounds is the charge they Coplands want on it in my area of the
country. They even write in the numbers when they ship it out. Copland looks at
all the weather conditions here and 3.8 pounds is what Copland wants in the unit
to be good in my area. SO Copland wanted 3.8 pounds of 22 in it and they were
very clear about it.
About being in the north or south we get Copland to judge the charge to set it
at from the factory. These two units was to be used in South Louisiana and the
charge it set by Copland 3.8 pounds for us. Other brands never use the Head
Master Valve as you say for we just don't have that stuff on equipment. i think
about all the equipment sold has nothing on it to keep the head up but if you
want to put a fan head pressure control on it you can.
Also I run the head pressure up to 300+ psi on the head by cutting off the
condenser coil air and the sight glass staied clear. Also both was working good
at a 75ºF Ambiuant. It may work like this.
TURTLE
| |
| Power's Mechanical 2005-10-10, 11:21 pm |
| Curious, Rich....
When I installed the larger compressor on the Hankison setup this
summer, the OEM had me setting the 'Hot Gas Bypass' to get the suction
pressure up.... if I remember correctly now (-;.
This valve modulates, and does exactly what you say it does (in this
case), but I'm wondering why a adjustment might have been necessary in
what was essentially a high condenser inlet air situation?
This unit has two receivers, as I recall....
Jake
Ill take this one for you Rich. Jake the suction was lower because
the compressor is too large. We went through this already.
| |
|
| Power's Mechanical wrote:
> Curious, Rich....
>
> When I installed the larger compressor on the Hankison setup this
> summer, the OEM had me setting the 'Hot Gas Bypass' to get the suction
> pressure up.... if I remember correctly now (-;.
>
>
> This valve modulates, and does exactly what you say it does (in this
> case), but I'm wondering why a adjustment might have been necessary in
> what was essentially a high condenser inlet air situation?
>
>
> This unit has two receivers, as I recall....
>
>
> Jake
>
>
> Ill take this one for you Rich. Jake the suction was lower because
> the compressor is too large. We went through this already.
>
Yessir, We did... sure enough. The OEM, and Copeland, were OK with this,
if you recall. We even heard from a rep for the OEM here.
The thing runs just fine... as a matter of fact better than it ever did
with the 'undersized' Tecumseh in it.
My question was what effect the HGB had on the system, and why it
brought the suction back up to the TXV-happy 60?
I think Paul already answered that, but if you can enlighten me further,
I'm interested....
Jake
| |
| ..p.jm@see_my_sig_for_address.com 2005-10-10, 11:21 pm |
| On Tue, 11 Oct 2005 01:45:25 GMT, Jake <jkelleyus@insightbb.com>
wrote:
>Power's Mechanical wrote:
Yeh, and you were proven utterly wrong, as always, because
you're an XXXXXXX.
[color=darkred]
>
>
>Yessir, We did... sure enough. The OEM, and Copeland, were OK with this,
>if you recall. We even heard from a rep for the OEM here.
>
>The thing runs just fine... as a matter of fact better than it ever did
>with the 'undersized' Tecumseh in it.
Damn I'm good :-)
>
>My question was what effect the HGB had on the system, and why it
>brought the suction back up to the TXV-happy 60?
>
>I think Paul already answered that, but if you can enlighten me further,
>I'm interested....
Before you even TALK with this XXXXXXX, remember that email I
sent you. He's the one. You might want to just K-file his stupid
scumbag XXX.
Click here every day to feed an animal that needs you today !!!
http://www.theanimalrescuesite.com/
Paul ( pjm @ pobox . com ) - remove spaces to email me
'Some days, it's just not worth chewing through the restraints.'
'With sufficient thrust, pigs fly just fine.'
HVAC/R program for Palm PDA's
Free demo now available online http://pmilligan.net/palm/
| |
|
|
>
>
> Damn I'm good :-)
My only regret is that a scroll should have gone in there.. but there
wasn't time to get one. Maybe next time around... if that ever happens.
The compressor runs like a champ, doesn't work very hard, and does a
great job. What more could you ask in a industrial setting?
We also replaced both condenser fan motors with Baldors, too. I think
it's good for a long while now!
>My question was what effect the HGB had on the system, and why it
>
>
> Before you even TALK with this XXXXXXX, remember that email I
> sent you. He's the one. You might want to just K-file his stupid
> scumbag XXX.
OK, if this is the guy... I'll certainly remember that. I don't killfile
anyone, at this point... I like to know everybody's views.
But that certainly doesn't keep me from ignoring or limiting my responses.
BTW, the poster seems to resemble those folks I've worked with in the
past who just keep putting the SAME EXACT model number of equipment in
things even though they continue to fail... month by month or year by
year, without asking WHY.
When I get something like a compressor or motor or control or whatever
that doesn't last its designed lifetime... I start looking for answers.
I'm not shy about calling Copeland (really nice people, btw) or
Hankison, or Tecumseh, or Baldor, or Allen Bradley, or whoever. Most of
the time, somebody has a answer.
The'answer' is NOT to throw the same part at a unit that has had two
compressor failures since 1997 and try again. The 'answer' is to talk to
everybody you can talk to at the OEM, the supplier, and alternate
suppliers to come up with a SOLUTION.
We'll see how this one works out long term.
Jake
| |
| ..p.jm@see_my_sig_for_address.com 2005-10-11, 12:21 am |
| On Tue, 11 Oct 2005 02:53:55 GMT, Jake <jkelleyus@insightbb.com>
wrote:
>
>
>My only regret is that a scroll should have gone in there.. but there
>wasn't time to get one. Maybe next time around... if that ever happens.
>The compressor runs like a champ, doesn't work very hard, and does a
>great job. What more could you ask in a industrial setting?
>
>We also replaced both condenser fan motors with Baldors, too. I think
>it's good for a long while now!
Did you ever do that little piece of duct ?
Click here every day to feed an animal that needs you today !!!
http://www.theanimalrescuesite.com/
Paul ( pjm @ pobox . com ) - remove spaces to email me
'Some days, it's just not worth chewing through the restraints.'
'With sufficient thrust, pigs fly just fine.'
HVAC/R program for Palm PDA's
Free demo now available online http://pmilligan.net/palm/
| |
|
|
>
>
> Did you ever do that little piece of duct ?
>
Done... with a moto ID/OD damper. The tinners recommended we go up to
the roofline and into the wind because the aircooled compressor
discharge was so close. You saw the pics... three 300 HP screws
discharging cooling air out that same wall. What a wacky design! I/R
gave it the okey=dokey!
Even with that, a inexpensive insurance policy.
The drier is on SCADA now, thanks to the great prints Bob from Hankison
sent me. Oh yes, he's the guy who was here......
Jake
| |
| PrecisionMachinisT 2005-10-11, 3:21 am |
|
"Power's Mechanical" <pusher100@hotmail.com> wrote in message
news:1128994031.195252.135080@f14g2000cwb.googlegroups.com...
>
> Ill take this one for you Rich. Jake the suction was lower because
> the compressor is too large. We went through this already.
>
And so we're back to the basic point that I had brought up at that time,
too...
In this app, you only need to keep supplying the evap with a sufficient
amount of heat...... remember--it's an air dryer...question being, you
suppose is it occasionally freezing up ???
Cause at that point, temporarily running a bypass makes perfect sense to
me...........
One could hope that eventually a larger evaporater might be installed, thus
finishing up with increasing the capacity of the entire system.
All in all, who cares if occasionally the moisture precipitates as a solid,
so long as it's quickly liquified and subsequently gets carried away from
the system before any major loss in capacity is experienced....not me--so
long as it all is indeed reliably precipitated.
--
SVL
| |
| Geoman1 2005-10-11, 1:22 pm |
| Paul, I'm not familiar with the other discussion, but it sounds like Jake
may not know the difference between a Head Master and a Hot Gas Bypass?
Jake, has Paul informed you of the differences of the two? If not, the two
items have little to do with each other except in some cases.
The Head Master control bypasses hot gas directly into the RECEIVER to raise
the pressure up on the liquid line. This is done when the outside or
condenser ambient is low and the low temperature causes the refrigerant to
condense so much in the condenser and receiver that the liquid line almost
turns into a vapor line. This in turn causes the TXV to be short liquid
refrigerant, which in turn reduces the net refrigeration to almost zero, no
boiling no refrigeration. The Head Master controls HEAD pressure. There are
other things in refrigeration terms that becomes obvious but its not needed
for this discussion. Both the Head Master and the HGB allows the unit to
not short cycle due to low suction pressure, but they are different in
curing the reason for the short cycling due to low suction pressure. The
Head Master control does nothing to control low capacity of the medium being
chilled, and the HGB has nothing to do with the low pressure of the
condenser when the outside temperature drops below normal designed
conditions. The HGB along with an unloader is a great way to control
accuracy in a lab environment where +/- of one degree or percentage of
humidity is critical. I can't think of any other method than HGB with
unloaders that will provide such accuracy.
Now, the HGB, (Hot Gas Bypass) bypasses hot gas directly into the low side
of the unit, usually on the TXV outlet side of the distributor. This hot gas
mixes with the atomized refrigerant out of the TXV and travels through the
coil and then reaches the bulb of the TXV. The HGB usually is adjusted for a
minimum outlet pressure and it adjusts accordingly. So you understand this,
the HGB adjusts its operation according to the pressure it sees on the
OUTLET side of the valve, it cares less about the pressure behind it on the
high side. Both the Head Master and the HGB allows the unit to not short
cycle due to low suction pressure, but they are different in correcting the
specific reasons for the short cycling due to low suction pressure. The TXV
bulb reads the superheat and adjusts its flow according to the superheat. If
the superheat goes down the TXV opens and allows more refrigerant flow, this
in turn increases the pressure so the HGB starts to shut down and modulate
according to pressure it senses on the OUTLET side of the HGB. They work
together. If the compressor has unloaders you can sometimes experience a
large amount of Hot Gas bypassing the system. Don't be too concerned if the
sight glass changes from solid to vapor as the HGB opens and closes. You
may, and I stress MAY have fan cycling controls with a Head Master Control
if a Hot Gas system is also used. This allows for a substantial savings in
receiver size and refrigerant quantity. I have seen dampers used that close
off the air to the condenser area and fan cycling. Carriers use to do this
on 30% of their condensers.
I hope I didn't repeat what Paul already stated in your other discussions
and hope I didn't confuse you.
Jake, for further information go to your refrigeration supplier and get a
Sporlan book with all the engineering literature. Sporlan is about the best
reading you can find on TXV's and other refrigerant designs and set up's.
http://www.sporlan.com/ I know they have this literature on the web but I
haven't been able to access it for two days now. I wonder what's up with
their site?
Rich
"Jake" <jkelleyus@insightbb.com> wrote in message
news:7PF2f.235189$084.71973@attbi_s22...
>
>
> My only regret is that a scroll should have gone in there.. but there
> wasn't time to get one. Maybe next time around... if that ever happens.
> The compressor runs like a champ, doesn't work very hard, and does a great
> job. What more could you ask in a industrial setting?
>
> We also replaced both condenser fan motors with Baldors, too. I think it's
> good for a long while now!
>
>
>
> OK, if this is the guy... I'll certainly remember that. I don't killfile
> anyone, at this point... I like to know everybody's views.
>
> But that certainly doesn't keep me from ignoring or limiting my responses.
>
> BTW, the poster seems to resemble those folks I've worked with in the past
> who just keep putting the SAME EXACT model number of equipment in things
> even though they continue to fail... month by month or year by year,
> without asking WHY.
>
> When I get something like a compressor or motor or control or whatever
> that doesn't last its designed lifetime... I start looking for answers.
> I'm not shy about calling Copeland (really nice people, btw) or Hankison,
> or Tecumseh, or Baldor, or Allen Bradley, or whoever. Most of the time,
> somebody has a answer.
>
> The'answer' is NOT to throw the same part at a unit that has had two
> compressor failures since 1997 and try again. The 'answer' is to talk to
> everybody you can talk to at the OEM, the supplier, and alternate
> suppliers to come up with a SOLUTION.
>
> We'll see how this one works out long term.
>
> Jake
| |
| Geoman1 2005-10-11, 1:22 pm |
|
"TURTLE" <turtle4aire@bellsouth.net> wrote in message
news:_Cv2f.4426$Yl.1508@bignews4.bellsouth.net...
>
> "Cooltemp Industries >" <gbroderick@sunlife.com> wrote in message
> news:Xns96EAE50D91564gbrodericksunlifecom@216.196.97.142...
>
> This is Turtle
>
> Glad to see a few poor devils tring to support this looser but hey Cool i
> don't care what is said about me as long as this stupid XXX hole Troll
> Paul is going with me and his software sales too. Paul Trolling like this
> sure helps his software sales. I would think you has not got a hit last
> week at all.
>
> One Sad thing here is Paul Troll is a looser and does not know it.
>
> TURTLE
There you go, Turtle, you should be in great shape. In your area using a
Head Master Control, you should never have to use a fan cycling control. I
hate fan cycling controls, they are hard on the fan motors, especially the
typical pressure on/off type where it just turns on and off the motor.
IF you experience high heads where the limit turns off the compressor, the
coil is perfectly clean and the fan is perfect, you may have an over charge
for your ambient condtions. I DOUBT however if this will ever happen because
this same unit would most likely get a few extra pounds of gas in our area,
and we get up to 98 degrees here too.
Rich
>
>
| |
|
| Rich,
Thank you for the detailed explanation here... very interesting.
Only one part I didn't get, though...
> The Head Master control bypasses hot gas directly into the RECEIVER to raise
> the pressure up on the liquid line. This is done when the outside or
> condenser ambient is low and the low temperature causes the refrigerant to
> condense so much in the condenser and receiver that the liquid line almost
> turns into a vapor line.
How can the refrigerant be so condensed that it turns the liquid line
into vapor? Is the temperature/pressure relationship altered in such a
way as to allow the liquid to flash in the liquid line?
> I hope I didn't repeat what Paul already stated in your other
discussions
> and hope I didn't confuse you.
> Jake, for further information go to your refrigeration supplier and get a
> Sporlan book with all the engineering literature. Sporlan is about the best
> reading you can find on TXV's and other refrigerant designs and set up's.
No Rich, my discussion with Paul on this issue has only directly
addressed how the HGB works in this instance... cooling compressed
air... so your comments are helpful to my understanding. Thanks!
I'll look for the Sporlan literature the next time I'm at one of the
bigger houses in Indy.
Jake
| |
| Power's Mechanical 2005-10-11, 10:21 pm |
| Before you even TALK with this XXXXXXX, remember that email I sent you.
He's the one.
>Fuck off PJ. Starting some clever whispering campain is just your style.
You might want to just K-file his stupid
scumbag XXX.
>Yeah do as I say not as I do huh XXXXXXX. Again fuck off.
| |
| TURTLE 2005-10-12, 12:21 am |
|
"Geoman1" <Geo1> wrote in message news:PdidnUSY0_AJf9beRVn-uQ@adelphia.com...
>
> "TURTLE" <turtle4aire@bellsouth.net> wrote in message
> news:_Cv2f.4426$Yl.1508@bignews4.bellsouth.net...
>
> There you go, Turtle, you should be in great shape. In your area using a Head
> Master Control, you should never have to use a fan cycling control. I hate fan
> cycling controls, they are hard on the fan motors, especially the typical
> pressure on/off type where it just turns on and off the motor.
>
> IF you experience high heads where the limit turns off the compressor, the
> coil is perfectly clean and the fan is perfect, you may have an over charge
> for your ambient condtions. I DOUBT however if this will ever happen because
> this same unit would most likely get a few extra pounds of gas in our area,
> and we get up to 98 degrees here too.
>
This is Turtle.
Yea , We don't get too hot here and only get to about 110ºF sometimes and 120ºF
on rooftops. This Head Master thing is kind of new down here and we will have to
see. If the Head Master will replace the fan control will be a good things but
one thing there is to concider and that is we sell replacement parts. I found
the fan controls will malfuction about every 5 years but not effect the motor
starting and stopping all the time in cold weather. The cold weather , I think
saves the fan motor and not be in the heat and stop and sarting all the time. I
keep a case of Head Pressure Fan control on hand all the time. I have found also
that a lot of 14 seer will not work well without a head pressure up to get a 125
psi differencial from head to suction pressure. I see a lot of the 13 or 14 seer
that will not cool in 40ºF or less in outdoor weather. All the Telephone
companys and computor rooms have to cool in cold weather have to have these fan
controls. These 13 and up seer units was a very good thing for the fan control
sales.
TURTLE
| |
| TURTLE 2005-10-13, 1:21 am |
|
<..p.jm@see_my_sig_for_address.com> wrote in message
news:q17mk1poc2a84vukdk1c8l9p0gpr4vdfmk@4ax.com...
> On Tue, 11 Oct 2005 01:45:25 GMT, Jake <jkelleyus@insightbb.com>
> wrote:
>
>
> Yeh, and you were proven utterly wrong, as always, because
> you're an XXXXXXX.
>
>
> Damn I'm good :-)
>
>
> Before you even TALK with this XXXXXXX, remember that email I
> sent you. He's the one. You might want to just K-file his stupid
> scumbag XXX.
>
This is Turtle.
OH MY GOD , Mike said a bad 4 letter word about somebody.
TURTLE
| |
| Carolina Breeze HVAC 2005-10-14, 2:21 pm |
|
"TURTLE" <turtle4aire@bellsouth.net> wrote in message
news:xDk3f.6825$Ls.3452@bignews2.bellsouth.net...
>
> <..p.jm@see_my_sig_for_address.com> wrote in message
> news:q17mk1poc2a84vukdk1c8l9p0gpr4vdfmk@4ax.com...
>
> This is Turtle.
>
> OH MY GOD , Mike said a bad 4 letter word about somebody.
>
> TURTLE
it was 7 letters...
You cant count well either..
>
| |
| TURTLE 2005-10-14, 11:21 pm |
|
"Carolina Breeze HVAC" <steve@carolinabreezehvac.com> wrote in message
news:jyR3f.80$rT.735@eagle.america.net...
>
> "TURTLE" <turtle4aire@bellsouth.net> wrote in message
> news:xDk3f.6825$Ls.3452@bignews2.bellsouth.net...
>
> it was 7 letters...
> You cant count well either..
>
This is Turtle.
The last time i check on how many letters it was in the word ''scum '' it was 4
but maybe you can count better.
TURTLE
| |
| Geoman1 2005-10-19, 8:21 pm |
| Jake, I'm sorry that I didn't respond until now, I've been busy lately.
"Jake" <jkelleyus@insightbb.com> wrote in message
news:%fY2f.423252$x96.385356@attbi_s72...
> Rich,
>
> Thank you for the detailed explanation here... very interesting.
>
> Only one part I didn't get, though...
>
>
>
> How can the refrigerant be so condensed that it turns the liquid line into
> vapor? Is the temperature/pressure relationship altered in such a way as
> to allow the liquid to flash in the liquid line?
No, and I may be incorrect in my explaination here so if anyone notices and
error please step in and correct me.
The way I have always understood it is this way.
The condenser volume is made up of hot superheated gas, condensed gas and
some sub cooled gas. When the temperature drops to a low ambient
temperature, the condenser becomes so efficient that the volume of the vapor
gas and superheated gas greatly reduces, in other words, the portion that
would be used as vapor converting to liquid isn't used for that any more,
the gas condensers so quickly in the first few passes of the the condenser
that most of the refrigerant is held in the condenser. The liquid is then
passed into the reciever which has a pick up tube on the bottom to grab the
liquid, but the reciever becomes short of liquid because its all in the
condenser as liquid, so the pick up tube picks up vapor and some liquid due
to the liquid being mostly in the condenser. To over come this problem we
cycle the fan, which is widely done but not the best solution. We also use a
head master which dumps hot gas directly into the reciever to raise the
pressure and volume of liquid, remember, the charge is increased for this
control, this allows a 'flooded' condenser and hot gas then allows the
volume of the liquid to still allow a 'liquid seal' at the pick up tube and
to allow the required 110 condensing temperature/pressure relationship to
cause the TXV to feed properly.
Now, concerning the condenser portion of the refrigeration system, it is
sized to allow the systems removed BTU and the compressors heat of
compression and energy output to be removed from the refrigerant at a given
ambient. When we size refrigeration systems it is based upon the condensers
abient temperatures. If you put a refrigeration system in a place that will
only see 80F and use the same thing at Vickies customers it won't work
because the condenser would be undersized. This is why some parts of the
country a 1/3 HP compressor will work for a two door freezer and others it
takes a 1/2 hp unit. So, if in Vickies area it goes to 115F outside and the
unit moves 10,000 btu, the same system here would remove maybe 15,000 BTU at
80F. But take that same system down to zero and the condenser is so grossly
oversized it wont run because all the refrigerant will condense into the
condenser, its like putting a HUGE condenser on the system, which in turn
would make the unit undercharged for that ambient condition. Many people in
the south are not familiar with low ambient problems and when cold weather
comes they think, 'WOW, its low on gas but I couldn't find a leak!" Then
when it warms up the unit is overcharged and going off on high head pressure
or it wipes out a compressor.
I hope I've made sence and I'm not in error about anything. Oh, also,
companies like Larking use to install calrod heaters on their recievers to
keep them warm. What a waiste of energy that type of system is
>
> discussions
>
> No Rich, my discussion with Paul on this issue has only directly addressed
> how the HGB works in this instance... cooling compressed air... so your
> comments are helpful to my understanding. Thanks!
>
> I'll look for the Sporlan literature the next time I'm at one of the
> bigger houses in Indy.
>
> Jake
>
>
| |
|
| Rich...
Thanks for the detailed explanation, again.
I think I get it now.
You have a closed-loop system with a set volume of refrigerant (in
whatever state it's in at any point in time).
A condenser running on a lower than designed ambient would condense the
gas so quickly that system volume (designed balance) is upset to the
point where starving can occur... because there is just not enough
volume in the system to compensate for so much gas changing state to
liquid at one time.
Does this sound about right, or am I still missing it?
Jake
| |
|
|
Jake wrote:
> Rich...
>
> Thanks for the detailed explanation, again.
>
> I think I get it now.
>
> You have a closed-loop system with a set volume of refrigerant (in
> whatever state it's in at any point in time).
>
> A condenser running on a lower than designed ambient would condense the
> gas so quickly that system volume (designed balance) is upset to the
> point where starving can occur... because there is just not enough
> volume in the system to compensate for so much gas changing state to
> liquid at one time.
>
> Does this sound about right, or am I still missing it?
Rich, Jake, I suggest the following:
http://www.achrnews.com/CDA/Article...,139280,00.html
hvacrmedic
| |
|
|
| ~^Johnny^~ 2005-10-20, 10:21 am |
| On Wed, 19 Oct 2005 18:21:02 -0400, "Geoman1" <Geo1> wrote:
> When the temperature drops to a low ambient
>temperature, the condenser becomes so efficient that the volume of the vapor
>gas and superheated gas greatly reduces, in other words, the portion that
>would be used as vapor converting to liquid isn't used for that any more,
>the gas condensers so quickly in the first few passes of the the condenser
>that most of the refrigerant is held in the condenser. The liquid is then
>passed into the reciever which has a pick up tube on the bottom to grab the
>liquid, but the reciever becomes short of liquid because its all in the
>condenser as liquid, so the pick up tube picks up vapor and some liquid due
>to the liquid being mostly in the condenser.
Huh???
Is the receiver *above* the condenser, then?
If so, this is generally bad design.
--
-john
wide-open at throttle dot info
| |
| Geoman1 2005-10-20, 9:21 pm |
|
"~^Johnny^~" <nospam@gyrogearloose.com> wrote in message
news:g83fl1pt5kfoqtsmcmp3pnl5ag62bdn063@4ax.com...
> On Wed, 19 Oct 2005 18:21:02 -0400, "Geoman1" <Geo1> wrote:
>
>
> Huh???
>
> Is the receiver *above* the condenser, then?
> If so, this is generally bad design.
>
> --
> -john
> wide-open at throttle dot info
No, I don't see where I you get the idea that I was referring to the
receiver being above the condenser, though it is possible to do this, it
isn't commonly done.
Rich
| |
| Geoman1 2005-10-20, 9:21 pm |
|
"Jake" <jkelleyus@insightbb.com> wrote in message
news:BwA5f.448622$_o.214106@attbi_s71...
> Rich...
>
> Thanks for the detailed explanation, again.
>
> I think I get it now.
>
> You have a closed-loop system with a set volume of refrigerant (in
> whatever state it's in at any point in time).
>
> A condenser running on a lower than designed ambient would condense the
> gas so quickly that system volume (designed balance) is upset to the point
> where starving can occur... because there is just not enough volume in the
> system to compensate for so much gas changing state to liquid at one time.
>
> Does this sound about right, or am I still missing it?
>
> Jake
Jake, here are two sites for you. Sporlan is king when it comes to
information for the tech.
http://www.sporlan.com/90-30.htm
http://www.sporlan.com/prvs.shtm
Rich
| |
| Geoman1 2005-10-20, 9:21 pm |
| [color=darkred]
Excellent Article!! Just what I was trying to say but it went deeper in
mentioning the reduction of TXV capacity.
Now, when you go here check out on the bottom list the next article,
"Maintaining Head Pressure Control" This is another excellent article for
you Jake.
Thank RP for this great link.
Rich
| |
|
| >
> Thank RP for this great link.
>
> Rich
>
>
Yes... thanks!
Jake
| |
| ~^Johnny^~ 2005-10-21, 8:21 am |
| On Thu, 20 Oct 2005 19:55:42 -0400, "Geoman1" <Geo1> wrote:
>
>"~^Johnny^~" <nospam@gyrogearloose.com> wrote in message
>news:g83fl1pt5kfoqtsmcmp3pnl5ag62bdn063@4ax.com...
>
>No, I don't see where I you get the idea that I was referring to the
>receiver being above the condenser, though it is possible to do this, it
>isn't commonly done.
>
>Rich
>
I was asking, because the faster the gas desuperheats and condenses,
the *more* liquid there will be in the receiver (or condenser, if no
receiver). Of course, no TXV can flow enough liquid if the head
pressure goes too low, so the *evaporator* will starve. Suction
pressure will go very low, reducing volume pumped by the compressor,
partially offsetting the increased reverse carnot efficiency imposed
by the lowered compression ratio/temp ratio.
BTW, I'll read that article Jake pointed out, tomorrow, if my new
card gets here in the post.
I have other cards, but I never use those online, not even PayPal.
As an aside:
Some bastard in Los Angeles cloned my VISA card the other day, and at
least three copies were floating around, so I had it cancelled
immediately. I don't know *exactly** how they do this, except by
brute force guessing, since the expiration dates and billing info
were all wrong, and different for each "clone". Yuck. It was the
one I use online, too. I'll catch the bastard. And then I'll sue...
Oh well, life in the fast lane. Still pisses me off royally.
It can happen to you!
--
-john
wide-open at throttle dot info
| |
| Geoman1 2005-10-21, 10:21 am |
|
"~^Johnny^~" <nospam@gyrogearloose.com> wrote in message
news:g8hhl116lvgjltif63bv4perbk4418if61@4ax.com...
> On Thu, 20 Oct 2005 19:55:42 -0400, "Geoman1" <Geo1> wrote:
>
>
>
> I was asking, because the faster the gas desuperheats and condenses,
> the *more* liquid there will be in the receiver (or condenser, if no
> receiver). Of course, no TXV can flow enough liquid if the head
> pressure goes too low, so the *evaporator* will starve. Suction
> pressure will go very low, reducing volume pumped by the compressor,
> partially offsetting the increased reverse carnot efficiency imposed
> by the lowered compression ratio/temp ratio.
Johnny, I think you have a few things out of place and I hope that I can
explain it correctly
The condenser is sized for only about 20% for liquid, the 80% that is left
is for desuperheating and condensing the vapor gas into a liquid. When you
change the ambient to a much lower temperature your condenser becomes
extremely oversized because it is designed at 85 to 95 degrees ambient for
most conditions. Therefore, your system becomes short of refrigerant because
it all condenses into the condenser. The receiver is sized to hold 80% of
the charge at 95F as well, so if my outside temp is 40F or lower most of the
liquid will be in the condenser, starving the receiver.
The other point is the TXV and the compressor. The compressor compression
ratio is greatly reduced so capacity increases dramatically, able to pump
much larger volumes of refrigerant. However, the TXV is designed for a
specific pressure differential, which Sporlan has charts for. When the
outside temperature drops so does the pressure, the Pressure Differential
across the TXV is reduced sot he TXV starves the evaporator but the
compressor can pump more due to lower compression ratio's. The result is
the system short cycles, oil doesn't return, and an uneducated service
person will add gas, thinking that the system is low. Then when the temp
outside warms up the unit is severely overcharged.....
The fan cycling pressure control helps but if you have zero outside like we
do and 15 MPH winds the fan cycling isn't enough. The head master control
solves this problem.
Hope this helps to understand the situation better. Also, I don't have time
to spell check, I've got to go to a job ASAP
Rich
> BTW, I'll read that article Jake pointed out, tomorrow, if my new
> card gets here in the post.
>
> I have other cards, but I never use those online, not even PayPal.
>
> As an aside:
> Some bastard in Los Angeles cloned my VISA card the other day, and at
> least three copies were floating around, so I had it cancelled
> immediately. I don't know *exactly** how they do this, except by
> brute force guessing, since the expiration dates and billing info
> were all wrong, and different for each "clone". Yuck. It was the
> one I use online, too. I'll catch the bastard. And then I'll sue...
>
> Oh well, life in the fast lane. Still pisses me off royally.
>
>
> It can happen to you!
>
>
>
> --
> -john
> wide-open at throttle dot info
| |
|
|
Geoman1 wrote:
> "~^Johnny^~" <nospam@gyrogearloose.com> wrote in message
> news:g8hhl116lvgjltif63bv4perbk4418if61@4ax.com...
>
>
>
> Johnny, I think you have a few things out of place and I hope that I can
> explain it correctly
>
> The condenser is sized for only about 20% for liquid, the 80% that is left
> is for desuperheating and condensing the vapor gas into a liquid. When you
> change the ambient to a much lower temperature your condenser becomes
> extremely oversized because it is designed at 85 to 95 degrees ambient for
> most conditions. Therefore, your system becomes short of refrigerant because
> it all condenses into the condenser. The receiver is sized to hold 80% of
> the charge at 95F as well, so if my outside temp is 40F or lower most of the
> liquid will be in the condenser, starving the receiver.
>
> The other point is the TXV and the compressor. The compressor compression
> ratio is greatly reduced so capacity increases dramatically, able to pump
> much larger volumes of refrigerant. However, the TXV is designed for a
> specific pressure differential, which Sporlan has charts for. When the
> outside temperature drops so does the pressure, the Pressure Differential
> across the TXV is reduced sot he TXV starves the evaporator but the
> compressor can pump more due to lower compression ratio's. The result is
> the system short cycles, oil doesn't return, and an uneducated service
> person will add gas, thinking that the system is low. Then when the temp
> outside warms up the unit is severely overcharged.....
>
> The fan cycling pressure control helps but if you have zero outside like we
> do and 15 MPH winds the fan cycling isn't enough. The head master control
> solves this problem.
>
> Hope this helps to understand the situation better. Also, I don't have time
> to spell check, I've got to go to a job ASAP
>
>
> Rich
That isn't entirely correct Rich. Without head pressure control, the
condenser won't have more liquid in it when the OAT drops, it will
actually have less liquid in it. The problem at low ambients is pressure
differential alone. If the evap temp is 20ºF and the ODT is lower than
this, then a saturated evap would mean a negative differential across
the TXV, and refrigerant would actually want to flow backward through
the TXV. This is an impossible situation though, what happens instead is
that the evaporator is starved of refrigerant, the superheat will run
abnormally high, and the suction pressure abnormally low. Under these
conditions you would indeed have to grossly overcharge the system in
order to get head pressure up high enough to feed the evap correctly.
The Headmaster (or equivalent) provides the same effect as an
overcharge, i.e. it backs up liquid into the condenser coil. On another
note, the only purpose of the coil bypass line is to equalize the
pressure on either side of the control.
hvacrmedic
>
>
>
| |
| ~^Johnny^~ 2005-10-21, 4:21 pm |
| On Fri, 21 Oct 2005 08:55:42 -0400, "Geoman1" <Geo1> wrote:
>Johnny, I think you have a few things out of place and I hope that I can
>explain it correctly
I've been wrong before...
>The condenser is sized for only about 20% for liquid, the 80% that is left
>is for desuperheating and condensing the vapor gas into a liquid.
Correct, but the condenser can hold up to 33% liquid, in a cap tube
system.
>When you
>change the ambient to a much lower temperature your condenser becomes
>extremely oversized because it is designed at 85 to 95 degrees ambient for
>most conditions.
>Therefore, your system becomes short of refrigerant because
>it all condenses into the condenser.
This is where I disagree. It is well known that, in cooler ambients,
most of the refrigerant will migrate to the high side. But it's all
there, so the system isn't short! It just ain't getting to the
evaporator very well!
>The receiver is sized to hold 80% of
>the charge at 95F as well, so if my outside temp is 40F or lower most of the
>liquid will be in the condenser, starving the receiver.
How is that? The receiver should be full!
The condenser drains into the receiver.
If teh receiver is below the condenser, it will be plumb full.
If it is beside the condenser, then liquid seeks its own level,
so the level in both the receiver and condenser should be pert near
the same.
>
>The other point is the TXV and the compressor. The compressor compression
>ratio is greatly reduced so capacity increases dramatically, able to pump
>much larger volumes of refrigerant.
Rich, decreased compression ratio increases the *efficiency*, not
so much the *capacity*. The refrigerant flow rate per ton, in pounds
per minute, is always
200 * (Hd-Hs/Hc-He),
regardless of what you're punping, at any pressure drop.
Granted, if COP increases at any refrigerant flow rate, then
*cooling capacity* will increase accordingly, but there is a limit.
And, you can't increase pumping mass without either raising the
backpressure or revving up the compressor RPMs.
For the same compressor, a higher mass pumped (higher back pressure
or denser gas) means higher possible capacity, but then the orifice
tube or expansion valve must be made bigger (sized accordingly), or
it still ain't gonna happen. Liquid will just migrate to the high
side, restricted by the expansion valve, no matter if it's wide
open.
Oversized, or multiple, staged, TXV's could help in this situation.
>However, the TXV is designed for a
>specific pressure differential, which Sporlan has charts for. When the
>outside temperature drops so does the pressure, the Pressure Differential
>across the TXV is reduced sot he TXV starves the evaporator
Here we agree. This is what I said!
>but the
>compressor can pump more due to lower compression ratio's.
I don't believe it. Vapor volume is vapor volume.
The compressor can only pump what it can suck in, per each revolution.
Now, at lower back pressures, this means a lower mass, so less gas
is pumped. Compressors are rated in btuh, according to their
physical displacement, at a given *backpressure*. It doesn't matter
the head pressure (well, it does, but let's ignore it for the time
being) - lower backpressure = lower capacity (max), due to lower mass
pumped. I did say *volume* earlier, and that was a mistake - it's
*mass*.
>The result is
>the system short cycles, oil doesn't return, and an uneducated service
>person will add gas, thinking that the system is low. Then when the temp
>outside warms up the unit is severely overcharged.....
Yes, it will probably short cycle.
Yes, I have seen a *pro* come out to a system I HAD BUILT and add
Freon it didn't need. The had boss called the guy out, because I was
out with injuries (collecting Worker's Comp, so I couldn't work
legally). This was back in the '80s, when R12 was still cheap, so
adding refrigerant was no biggie in the pocketbook, compared to the
overall invoice.
Shit, when I was a kid, my dad used to blow the dust out of coils
with R12, as if it were compressed air. Waste not, want not, was
not an issue for Dad in the 50's and 60's.
>
>The fan cycling pressure control helps but if you have zero outside like we
>do and 15 MPH winds the fan cycling isn't enough. The head master control
>solves this problem.
Well, you don't even need the condenser fan in this case. :-)
Hell, you don't even need A/C! If you're cooling a computer room,
for instance, all you need is a simple coolant loop, or exhaust and
intake fans. Running A/C in winter is ludicrous, except for humidity
control, and then there are dehumidifiers or coolant loops.
>Hope this helps to understand the situation better. Also, I don't have time
>to spell check, I've got to go to a job ASAP
Yuu tookk the time too type it inn, and teh speling is fine. :-)
--
-john
wide-open at throttle dot info
| |
| ~^Johnny^~ 2005-10-21, 4:21 pm |
| On Fri, 21 Oct 2005 12:04:53 -0500, RP <no_mail_no_spam@yahoo.com>
wrote:
>That isn't entirely correct Rich. Without head pressure control, the
>condenser won't have more liquid in it when the OAT drops, it will
>actually have less liquid in it. The problem at low ambients is pressure
>differential alone. If the evap temp is 20ºF and the ODT is lower than
>this, then a saturated evap would mean a negative differential across
>the TXV, and refrigerant would actually want to flow backward through
>the TXV. This is an impossible situation though, what happens instead is
>that the evaporator is starved of refrigerant, the superheat will run
>abnormally high, and the suction pressure abnormally low. Under these
>conditions you would indeed have to grossly overcharge the system in
>order to get head pressure up high enough to feed the evap correctly.
Very well said!
--
-john
wide-open at throttle dot info
| |
| ~^Johnny^~ 2005-10-21, 4:21 pm |
| On Fri, 21 Oct 2005 11:53:17 -0700, ~^Johnny^~
<nospam@gyrogearloose.com> wrote:
>The had boss called the guy out
Yipes! Dyslexia is setting in. ;`(
--
-john
wide-open at throttle dot info
| |
| Geoman1 2005-10-21, 7:21 pm |
| RP,
I've read your post several times and I think we are saying the same thing
but we are coming at different angles. I will try to post inside the texts.
>
> That isn't entirely correct Rich. Without head pressure control, the
> condenser won't have more liquid in it when the OAT drops, it will
> actually have less liquid in it.
Maybe a better way of saying what I wanted to say is not 'more' liquid
refrigerant in the condenser but most of the charge will be in the condenser
as a liquid, starving the reciever and other parts of the system. Your TXV
will not have a solid columb and it wont have the Delta P to maintain the
proper flow of refrigerant, unless its a Bohnamatic TXV which only requires
5 PSI Differential. The Low OAT creates a shortage of refrigerant in the
reciever, to prove this fact one can overcharge the system and make it work.
The condenser is way oversized for low ambient conditions, and if you
install an ORI/ORD or an OROA into a system, you must add gas for the system
to operate, Why? Because it holds back the refrigerant in the condenser
and the reciever would be short without the extra gas. This same thing is
true without these controls. The condenser being oversized in low ambient
conditions creates a shortage of liquid in the reciever and too low of a
pressure to work properly with the TXV, once again, unless your using a
Bohamizer TXV system or something simular.
Since there isn't much pressure difference between the suction side and the
head pressure the liquid moves slowly, pressure is too low on the high side
to overcome the TXV settings and the distributors and orifice and the result
is short cycling.
With the ORI/ORD etc controls, they hold back the liquid refrigerant, the
EXTRA amount of charge that is determined by the lowest ambient temperature
is what bypasses the condenser as hot gas into the reciever, mixed with some
liquid from the condenser. This results as pressure in the reciever
increasing, the reciever pressure is increased, a solid columb of liquid is
above the opening of the dip tube, and the recievers capacity is still low
enough to accomodate the liquid gas held back in the condenser when the
weather warms up and the head master goes into standby mode.
The problem at low ambients is pressure
> differential alone.
I agree with you, it is a pressure problem. With a Bohnamizer TXV it is not
as big of a problem because the TXV can opperate with a 5PSI differential.
Bohn solves the little problem with extreme low temperatures by using a low
temp thermostat Klixon switch and locks out one fan. Also, it is possible to
put a liquid line pump and increase the pressure to the TXV and not use head
pressure controls but this isn't a cheap solution for five ton units or
less. This pump also works on long liquid lines to maintain lift. However,
I still envision the condenser holding more refrigerant during low ambient
conditions than normal, creating a shortage of gas in the reciever.
Installing a head pressure control won't solve anything unless you add gas
and may possibly have to add reciever capacity.
If the evap temp is 20ºF and the ODT is lower than
> this, then a saturated evap would mean a negative differential across the
> TXV, and refrigerant would actually want to flow backward through the TXV.
> This is an impossible situation though, what happens instead is that the
> evaporator is starved of refrigerant, the superheat will run abnormally
> high, and the suction pressure abnormally low. Under these conditions you
> would indeed have to grossly overcharge the system in order to get head
> pressure up high enough to feed the evap correctly.
Agreed,
>
> The Headmaster (or equivalent) provides the same effect as an overcharge,
> i.e. it backs up liquid into the condenser coil.
Back up most of the refrigerant into the coil but not the added amount
needed for the headmaster. That amount is for the reciever, give or take a
portion of the charge, I'm not trying to indicate a specific percentage
here.
On another
> note, the only purpose of the coil bypass line is to equalize the pressure
> on either side of the control.
>
> hvacrmedic
I really think we are saying the same thing. The only difference I can see
is my idea/view that the condenser having most of the liquid in it
immediatly after start up, I will certainly change my views if necessary ...
BTW, the idea of the flow of refrigerant wanting to flow backwards is like
my one Email engineer friend from Mexico City. He built a jet motocycle. The
weierd part of the bike is with the fast acceleration, he says its strange
hearing the screaching of the tires when they aren't moving and the become
quiet when they start to roll the proper RPM according to speed, your
example is just about the same type of mind blowing thought! It just goes
against what we sometimes think as logic.
Rich
>
>
>
>
| |
|
|
Geoman1 wrote:
> RP,
>
> I've read your post several times and I think we are saying the same thing
> but we are coming at different angles. I will try to post inside the texts.
>
>
>
>
> Maybe a better way of saying what I wanted to say is not 'more' liquid
> refrigerant in the condenser but most of the charge will be in the condenser
> as a liquid, starving the reciever and other parts of the system. Your TXV
> will not have a solid columb and it wont have the Delta P to maintain the
> proper flow of refrigerant, unless its a Bohnamatic TXV which only requires
> 5 PSI Differential.
Two points to make here Rich. The receiver will be the natural
collection point for the liquid. When there is no receiver present a
starved evap does mean an over-saturated condenser, but with the
receiver present this no longer applies because there is no longer a
metering device at the condenser/liquid line outlet to back the liquid
up into the condenser. The liquid is backed up into the receiver
instead. The only way to get a solid stream of liquid (100% mixture)
flowing into the receiver is to fill the receiver completely. In a
partially filled receiver there is vapor present. This vapor is actively
condensing in the receiver and thus it must be actively replenished.
The reason that there will be less liquid in the condenser as OAT drops
is thermal contraction of the liquid.
hvacrmedic
> The Low OAT creates a shortage of refrigerant in the
> reciever, to prove this fact one can overcharge the system and make it work.
> The condenser is way oversized for low ambient conditions, and if you
> install an ORI/ORD or an OROA into a system, you must add gas for the system
> to operate, Why? Because it holds back the refrigerant in the condenser
> and the reciever would be short without the extra gas. This same thing is
> true without these controls. The condenser being oversized in low ambient
> conditions creates a shortage of liquid in the reciever and too low of a
> pressure to work properly with the TXV, once again, unless your using a
> Bohamizer TXV system or something simular.
>
> Since there isn't much pressure difference between the suction side and the
> head pressure the liquid moves slowly, pressure is too low on the high side
> to overcome the TXV settings and the distributors and orifice and the result
> is short cycling.
>
> With the ORI/ORD etc controls, they hold back the liquid refrigerant, the
> EXTRA amount of charge that is determined by the lowest ambient temperature
> is what bypasses the condenser as hot gas into the reciever, mixed with some
> liquid from the condenser. This results as pressure in the reciever
> increasing, the reciever pressure is increased, a solid columb of liquid is
> above the opening of the dip tube, and the recievers capacity is still low
> enough to accomodate the liquid gas held back in the condenser when the
> weather warms up and the head master goes into standby mode.
>
>
>
> The problem at low ambients is pressure
>
>
>
> I agree with you, it is a pressure problem. With a Bohnamizer TXV it is not
> as big of a problem because the TXV can opperate with a 5PSI differential.
> Bohn solves the little problem with extreme low temperatures by using a low
> temp thermostat Klixon switch and locks out one fan. Also, it is possible to
> put a liquid line pump and increase the pressure to the TXV and not use head
> pressure controls but this isn't a cheap solution for five ton units or
> less. This pump also works on long liquid lines to maintain lift. However,
> I still envision the condenser holding more refrigerant during low ambient
> conditions than normal, creating a shortage of gas in the reciever.
> Installing a head pressure control won't solve anything unless you add gas
> and may possibly have to add reciever capacity.
>
>
> If the evap temp is 20ºF and the ODT is lower than
>
>
>
> Agreed,
>
>
>
>
>
> Back up most of the refrigerant into the coil but not the added amount
> needed for the headmaster. That amount is for the reciever, give or take a
> portion of the charge, I'm not trying to indicate a specific percentage
> here.
>
>
> On another
>
>
>
> I really think we are saying the same thing. The only difference I can see
> is my idea/view that the condenser having most of the liquid in it
> immediatly after start up, I will certainly change my views if necessary ...
>
> BTW, the idea of the flow of refrigerant wanting to flow backwards is like
> my one Email engineer friend from Mexico City. He built a jet motocycle. The
> weierd part of the bike is with the fast acceleration, he says its strange
> hearing the screaching of the tires when they aren't moving and the become
> quiet when they start to roll the proper RPM according to speed, your
> example is just about the same type of mind blowing thought! It just goes
> against what we sometimes think as logic.
>
> Rich
>
>
>
>
| |
| Power's Mechanical 2005-10-21, 8:21 pm |
| BTW, the idea of the flow of refrigerant wanting to flow backwards is
like
my one Email engineer friend from Mexico City. He built a jet
motocycle. The
weierd part of the bike is with the fast acceleration, he says its
strange
hearing the screaching of the tires when they aren't moving and the
become
quiet when they start to roll the proper RPM according to speed, your
example is just about the same type of mind blowing thought! It just
goes
against what we sometimes think as logic.
Rich
xxxx
Makes perfect sence to me Rich. When he hears the tires squeeling and
hes sitting still, thats called a burn out. When they quit squeeling
hes moving!
What a concept! lol
| |
| Geoman1 2005-10-21, 11:21 pm |
|
"Power's Mechanical" <pusher100@hotmail.com> wrote in message
news:1129935030.917887.72260@g47g2000cwa.googlegroups.com...
> BTW, the idea of the flow of refrigerant wanting to flow backwards is
> like
> my one Email engineer friend from Mexico City. He built a jet
> motocycle. The
> weierd part of the bike is with the fast acceleration, he says its
> strange
> hearing the screaching of the tires when they aren't moving and the
> become
> quiet when they start to roll the proper RPM according to speed, your
> example is just about the same type of mind blowing thought! It just
> goes
> against what we sometimes think as logic.
>
> Rich
>
> xxxx
>
> Makes perfect sence to me Rich. When he hears the tires squeeling and
> hes sitting still, thats called a burn out. When they quit squeeling
> hes moving!
>
> What a concept! lol
NO Mike, they squeal because they are NOT moving due to the thrust and rapid
take off the tires don't have a chance to roll so they,,,,, oh forget it!
:-)
Rich
| |
|
|
Geoman1 wrote:
> "Power's Mechanical" <pusher100@hotmail.com> wrote in message
> news:1129935030.917887.72260@g47g2000cwa.googlegroups.com...
>
>
>
>
> NO Mike, they squeal because they are NOT moving due to the thrust and rapid
> take off the tires don't have a chance to roll so they,,,,, oh forget it!
> :-)
Thrust causes the squeal rather than squeal causing the thrust.
Frictional force is opposite in direction to that of a burnout. Don't
worry, I got it. Also heard that one before 
hvacrmedic
| |
| Geoman1 2005-10-22, 12:21 am |
|
"RP" <no_mail_no_spam@yahoo.com> wrote in message
news:VfedneXrkJJEPcTeRVn-jA@centurytel.net...
>
>
> Geoman1 wrote:
>
> Thrust causes the squeal rather than squeal causing the thrust. Frictional
> force is opposite in direction to that of a burnout. Don't worry, I got
> it. Also heard that one before
>
> hvacrmedic
thanks, I've been looking for the video but can't find it. I haven't
emailed Miguel for over a year now and I think he switched to a different
site.
It was a cool vid that he had.........
BTW, I agree with you about the contraction of the refrigerant, I was just
telling Mark about that topic this last week. I was going to look up the
formula but just this last week I threw out four 32 gallon garbage cans of
books and literature, and I remember tossing out the info from Dupont that
taught the rate of contraction at given delta T's. It just figures.
Rich
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