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Home > Archive > Heating and air conditioning > February 2006 > Hey lets talk shop
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Hey lets talk shop
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| gofish@gonefishin.net 2006-02-04, 10:21 pm |
| non stop process load equals 15 tons. no other sources of heat gain.
The 15 ton 2 stage ac unit will achieve and hold setpoint (69°) at
outdoor temps 75+.
According to the manufacturer, the unit comes with low ambient
cooling, down as low as 40°F. CF2 is disabled at 60°, enabled at 65°.
However at 40° outdoor ambient, unit capacity is 60%. Economizer is
not an option, due to sensitive electronics in the room. Head
pressure kit on 1st stage cycles CF1 at ambients below 60°.
gawd damn mamafucker stillf freezes up. would hot gas bypass prevent
freezeups? any other ideas?
ok, back to bashing each other.
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| Power's Mechanical 2006-02-04, 10:21 pm |
| Air flow. HGB is not the answer.
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| Oscar_Lives 2006-02-05, 12:21 am |
|
<gofish@gonefishin.net> wrote in message
news:uhlau11kus1vub23gk2fe80msoovtga16b@4ax.com...
> non stop process load equals 15 tons. no other sources of heat gain.
> The 15 ton 2 stage ac unit will achieve and hold setpoint (69°) at
> outdoor temps 75+.
> According to the manufacturer, the unit comes with low ambient
> cooling, down as low as 40°F. CF2 is disabled at 60°, enabled at 65°.
> However at 40° outdoor ambient, unit capacity is 60%. Economizer is
> not an option, due to sensitive electronics in the room. Head
> pressure kit on 1st stage cycles CF1 at ambients below 60°.
>
> gawd damn mamafucker stillf freezes up. would hot gas bypass prevent
> freezeups? any other ideas?
>
> ok, back to bashing each other.
What's the latent load?
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| .p.jm@see_my_sig_for_address.com 2006-02-05, 12:21 am |
| On Sun, 05 Feb 2006 03:15:08 GMT, "Oscar_Lives" <nospam@nospam.net>
wrote:
>
><gofish@gonefishin.net> wrote in message
>news:uhlau11kus1vub23gk2fe80msoovtga16b@4ax.com...
I would answer your question, but you're an XXXXXXX so I
won't.
[color=darkred]
>
>What's the latent load?
>
--
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/
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gofish@gonefishin.net wrote:
> non stop process load equals 15 tons. no other sources of heat gain.
> The 15 ton 2 stage ac unit will achieve and hold setpoint (69°) at
> outdoor temps 75+.
> According to the manufacturer, the unit comes with low ambient
> cooling, down as low as 40°F. CF2 is disabled at 60°, enabled at 65°.
> However at 40° outdoor ambient, unit capacity is 60%. Economizer is
> not an option, due to sensitive electronics in the room. Head
> pressure kit on 1st stage cycles CF1 at ambients below 60°.
>
> gawd damn mamafucker stillf freezes up. would hot gas bypass prevent
> freezeups? any other ideas?
>
> ok, back to bashing each other.
So you are saying that you don't know what makes a coil freeze up?
Here's a list for you:
1) Starved evaporator.
2) Insufficient load on evaporator.
There are several possible causes of each of these, but these two are
the direct causes.
First, it should be obvious that if the system holds the load at 75º
ambient, then you wouldn't want your condenser fans to cycle off at temp
lower than this. While that might take care of the problem, it would
just be a patch. If the actual continuous load is 15 tons then your
system is undersized at 15 tons. The rating applies to design
conditions only, and then only when the system's performance is optimal.
Richard Perry
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| Murdentech 2006-02-05, 9:21 am |
| add more freon... the answer is always add more freon..... LOL
what type of low ambient kit are you using?
.... should maintain constant head pressure regardless of OAT
<gofish@gonefishin.net> wrote in message
news:uhlau11kus1vub23gk2fe80msoovtga16b@4ax.com...
> non stop process load equals 15 tons. no other sources of heat gain.
> The 15 ton 2 stage ac unit will achieve and hold setpoint (69°) at
> outdoor temps 75+.
> According to the manufacturer, the unit comes with low ambient
> cooling, down as low as 40°F. CF2 is disabled at 60°, enabled at 65°.
> However at 40° outdoor ambient, unit capacity is 60%. Economizer is
> not an option, due to sensitive electronics in the room. Head
> pressure kit on 1st stage cycles CF1 at ambients below 60°.
>
> gawd damn mamafucker stillf freezes up. would hot gas bypass prevent
> freezeups? any other ideas?
>
> ok, back to bashing each other.
| |
| James Storm 2006-02-05, 10:21 am |
| gofish@gonefishin.net wrote:
> non stop process load equals 15 tons. no other sources of heat gain.
> The 15 ton 2 stage ac unit will achieve and hold setpoint (69°) at
> outdoor temps 75+.
> According to the manufacturer, the unit comes with low ambient
> cooling, down as low as 40°F. CF2 is disabled at 60°, enabled at 65°.
> However at 40° outdoor ambient, unit capacity is 60%. Economizer is
> not an option, due to sensitive electronics in the room. Head
> pressure kit on 1st stage cycles CF1 at ambients below 60°.
>
> gawd damn mamafucker stillf freezes up. would hot gas bypass prevent
> freezeups? any other ideas?
>
> ok, back to bashing each other.
The most likely cause for your coil to freeze up is the condenser fan
cycling. HGBP will indeed solve the problem, but has to be large enough
and set properly. If it were under my care I would recommend using VFD
to take total control of the condenser fans allowing steady 225# head
pressure. Since your internal load does not vary, by maintaining
constant condensing pressures your condenser load will remain constant.
Less invasive also.
--
James Storm
aka Stormy Weather
jstorm@ptd.net
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| James Storm wrote:
> gofish@gonefishin.net wrote:
>
>
>
> The most likely cause for your coil to freeze up is the condenser fan
> cycling. HGBP will indeed solve the problem, but has to be large enough
> and set properly. If it were under my care I would recommend using VFD
> to take total control of the condenser fans allowing steady 225# head
> pressure. Since your internal load does not vary, by maintaining
> constant condensing pressures your condenser load will remain constant.
> Less invasive also.
>
James,
we've actually done this on compressed air dryer systems that don't have
the benefit of HGBP.
Works like a charm, and drives are pretty cheap these days.
Works well on the OTHER end of the spectrum, too... when you need to get
more airflow across the condenser.
Jake
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| TURTLE 2006-02-11, 1:21 pm |
|
..p.jm@see_my_sig_for_address.com wrote:
> On Sun, 05 Feb 2006 03:15:08 GMT, "Oscar_Lives" <nospam@nospam.net>
> wrote:
>
5=B0.[color=darkred]
>
> I would answer your question, but you're an XXXXXXX so I
> won't.
>
This is Turtle.
I too would answer the quesion but like you and I both have not got a
clue! Stop this playing like you know the answers and being a know it
all and just answer the question you can answer openly. There is
nothing wrong with not knowing all the answers to all the question all
the time for Abraham Lincoln in his younger days said i'm not smart
enough to know it all and will always have friends to help me in my
times of need.
Paul you remind me of the fellow who puts Sniker Bars on his head to
cover up being bald headed. Give it up , everybody knowns about it.
TURTLE
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| In article <1139676486.474368.197920@f14g2000cwb.googlegroups.com>,
"TURTLE" <hvacturtle@gmail.com> wrote:
> This is Turtle.
>
> I too would answer the quesion but like you and I both have not got a
> clue! Stop this playing like you know the answers and being a know it
weasel you're a proven hack. Doesn't mean anybody else is. Crawl back
under your rock.
--
Paul's cat got a furball and kept saying weasel's name.
*Hack* *Hack* *hack*
| |
| TURTLE 2006-02-12, 1:21 pm |
| This is Turtle.
Bill stop telling Paul that putting snikers bars on his head will make
everybody think he is a hvac tech or worker in the buisiness. he is
nothing but a Software salesman in the hvac business.
TURTLE
| |
|
| In article <1139762543.475697.173560@g43g2000cwa.googlegroups.com>,
"TURTLE" <hvacturtle@gmail.com> wrote:
> This is Turtle.
>
> Bill stop telling Paul that putting snikers bars on his head will make
> everybody think he is a hvac tech or worker in the buisiness. he is
> nothing but a Software salesman in the hvac business.
Your jealousy would be funny if you weren't such a hack. Crawl back
under your rock weasel.
--
Paul's cat got a furball and kept saying weasel's name.
*Hack* *Hack* *hack*
| |
|
| Simple answer is yes hot gas will help
however how critical is this to you and how much money
do you are your customer willing to spend.
If you inject hot gas into evaporator you will need also
nice size accumulator, if you injected into suction line
In addition to accumulator you will need suction
pilot temperature valve.Remember both setups require
critical proper adjustments.
You will also require some type of head pressure control
this can be achieved two three different ways I will suggest
on this to check with you distributor for availability.
setups I describe to you can used on any size of HP
Good luck from Dido
<gofish@gonefishin.net> wrote in message
news:uhlau11kus1vub23gk2fe80msoovtga16b@4ax.com...
> non stop process load equals 15 tons. no other sources of heat gain.
> The 15 ton 2 stage ac unit will achieve and hold setpoint (69°) at
> outdoor temps 75+.
> According to the manufacturer, the unit comes with low ambient
> cooling, down as low as 40°F. CF2 is disabled at 60°, enabled at 65°.
> However at 40° outdoor ambient, unit capacity is 60%. Economizer is
> not an option, due to sensitive electronics in the room. Head
> pressure kit on 1st stage cycles CF1 at ambients below 60°.
>
> gawd damn mamafucker stillf freezes up. would hot gas bypass prevent
> freezeups? any other ideas?
>
> ok, back to bashing each other.
| |
|
| Simple answer is yes hot gas will help
however how critical is this to you and how much money
do you are your customer willing to spend.
If you inject hot gas into evaporator you will need also
nice size accumulator, if you injected into suction line
In addition to accumulator you will need suction
pilot temperature valve.Remember both setups require
critical proper adjustments.
You will also require some type of head pressure control
this can be achieved two three different ways I will suggest
on this to check with you distributor for availability.
setups I describe to you can used on any size of HP
Good luck from Dido
<gofish@gonefishin.net> wrote in message
news:uhlau11kus1vub23gk2fe80msoovtga16b@4ax.com...
> non stop process load equals 15 tons. no other sources of heat gain.
> The 15 ton 2 stage ac unit will achieve and hold setpoint (69°) at
> outdoor temps 75+.
> According to the manufacturer, the unit comes with low ambient
> cooling, down as low as 40°F. CF2 is disabled at 60°, enabled at 65°.
> However at 40° outdoor ambient, unit capacity is 60%. Economizer is
> not an option, due to sensitive electronics in the room. Head
> pressure kit on 1st stage cycles CF1 at ambients below 60°.
>
> gawd damn mamafucker stillf freezes up. would hot gas bypass prevent
> freezeups? any other ideas?
>
> ok, back to bashing each other.
| |
| ~^Johnny^~ 2006-02-23, 8:21 pm |
| On Mon, 13 Feb 2006 22:23:33 GMT, "Dido" <a.seput@verizon.net> wrote:
>Simple answer is yes hot gas will help
>however how critical is this to you and how much money
>do you are your customer willing to spend.
>If you inject hot gas into evaporator you will need also
>nice size accumulator, if you injected into suction line
>In addition to accumulator you will need suction
>pilot temperature valve.
Why not just install an ORIT (EPR valve) at the suction
port of the first stage? The system has to unload anyway,
and throttling the suction line is one simple way to do it.
Hot gas bypass is a waste, and a last resort.
I'd rather see an artificial load, like a part-time
suction line-to- discharge line (not liquid line) heat exchanger.
It desuperheats the hot gas while at the same time cutting capacity
and lowering headpressure without significantly lowering the ADP
(apparatus dew point).
Also, switching to a TXV is a must, externally equalized, if this is
a mod, anyway. It works hand in hand with the EPR to keep the
evaporator happy without freezing up.
--
-john
wide-open at throttle dot info
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| TURTLE 2006-02-23, 9:21 pm |
|
Bill wrote:
> In article <1139762543.475697.173560@g43g2000cwa.googlegroups.com>,
> "TURTLE" <hvacturtle@gmail.com> wrote:
>
>
> Your jealousy would be funny if you weren't such a hack. Crawl back
> under your rock weasel.
>
This is Turtle.
you poor devil , your under the rock looking at me out from under the
rock and thinking I'm under the rock. You poor Devil !
TURTLE
| |
| ~^Johnny^~ 2006-02-23, 9:21 pm |
| On Sat, 04 Feb 2006 21:32:51 -0600, RP <no_mail_no_spam@yahoo.com>
wrote:
>First, it should be obvious that if the system holds the load at 75º
>ambient, then you wouldn't want your condenser fans to cycle off at temp
>lower than this. While that might take care of the problem, it would
>just be a patch.
Exactly. And it's wasteful.
This would load the compressor, instead of unloading it, which is
not only less efficient, but harder on the compressor.
--
-john
wide-open at throttle dot info
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~^Johnny^~ wrote:
> On Sat, 04 Feb 2006 21:32:51 -0600, RP <no_mail_no_spam@yahoo.com>
> wrote:
>
>
>
>
>
> Exactly. And it's wasteful.
>
> This would load the compressor, instead of unloading it, which is
> not only less efficient, but harder on the compressor.
You didn't take my paragraph in context. If evaporator freezing only
occurs at low ambients, as per the OP, then condenser fan cycling can be
adjusted to prevent this. Given constant indoor conditions, also per the
OP, the only way that low ambient will cause freeze-up is by providing a
less than 100% mixture to the TXV or TEV. In this case, the capacity
will be increased by cycling the condenser fans at 75º, because the
evaporator will no longer starved. Contrary to your sentiments, the
compressor won't be stressed, because at a simulated ambient of 75º,
well I shouldn't have to explain. 
While you can add refrigerant to clear the sight glass at low ambients,
some manufacturers instructions warn against doing so, because the
system will then be overcharged. Since we can't see it from here, it is
even possible that the system is undercharged, but per the OP it isn't.
But I digress....Most chillers will operate ok down to 65º, but this one
obviously has too little load on the evaporator, and cannot run at
ambients lower than this until that problem is corrected. That's why I
called the above a "patch".
If you want to argue these points, then I'll only say that I'm not in
the mood to argue. I'm right, end of story.
Richard Perry
| |
|
| In article <1140741551.905841.70760@t39g2000cwt.googlegroups.com>,
"TURTLE" <hvacturtle@gmail.com> wrote:
>
> This is Turtle.
>
> you poor devil , your under the rock looking at me out from under the
> rock and thinking I'm under the rock. You poor Devil !
>
> TURTLE
Oh look weasel got a furlough from the nut house. Just when I thought
I'd change my sig too. lol
--
Paul's cat got a furball and kept saying weasel's name.
*Hack* *Hack* *hack*
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