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Geothermal Ground Source Heat Pump vs Oil Evaluation
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|
|
| Hello,
I'm about to make a big decision regarding installation of a ground
source heat pump (closed loop wells) and a traditional hydro air/boiler
oil-fire system. I'm looking for some advice/comments regarding the
assumptions/calcs. that I've made regarding cost savings. Here goes:
1. Southern New England temps.
2. heat loss calcs from me and others confirms about 85000 Btu/hr
3. Oil: $2.25/gal, furnace efficiency .85, $19/MBtu
4. Ground source heat pump: $.096/kWh, COP 4.1, $6.92/MBtu
5. 175MBtu/year <---is this right? This is roughly based on my previous
experience with an oil system scaled up for difference in square
footage between the homes. I realize this is VERY inaccurate. What
more information do I REASONABLY need for a more accurate number? Is
there an equation/rule of thumb?
6. Therefore, for savings calcs, Oil heat costs $3300/year and GSHP
heat costs $1200/year
8. $25000 (quoted) additional cost of GSHP over Oil, 11 to 12 years
payback of investment.
Any comments/suggestions are greatly appreciated as this is a really
big decision.
Thanks
| |
| nicksanspam@ece.villanova.edu 2005-10-01, 9:21 am |
| Johan <JohanKristoff@hotmail.com> wrote:
>I'm about to make a big decision regarding installation of a ground
>source heat pump (closed loop wells) and a traditional hydro air/boiler
>oil-fire system. I'm looking for some advice/comments regarding the
>assumptions/calcs. that I've made regarding cost savings. Here goes:
>1. Southern New England temps.
>2. heat loss calcs from me and others confirms about 85000 Btu/hr
On a very cold day, a 97.5 percentile winter temp?
>3. Oil: $2.25/gal, furnace efficiency .85, $19/MBtu
>4. Ground source heat pump: $.096/kWh, COP 4.1, $6.92/MBtu
>5. 175MBtu/year <---is this right?
About 1750 gallons of oil? Sounds like a lot.
>This is roughly based on my previous experience with an oil system scaled up
>for difference in square footage between the homes. I realize this is VERY
>inaccurate. What more information do I REASONABLY need for a more accurate
>number? Is there an equation/rule of thumb?
Your heat loss calc should lead to a thermal conductance from indoors to
outdoors, eg 400 Btu/h-F. Multiply that by 24 (hours) and the number of
heating degree days in your climate, eg 5641 in Boston. So, a 400 Btu/h-F
house in Boston would need 24x400x5641 = 54 million Btu of heat. Some of
that may come from indoor electrical usage and sun into windows. Then again,
you might forget all this heat pumping and solar heat the house, 100%, or
add a sunspace or some polycarbonate "solar siding" air heaters on the south
wall. Be sure to make the house extremely airtight, less than 0.2 ACH,
with a blower door test.
You might also consider cogeneration, eg a 6 kW water-cooled Honda.
Nick
| |
| pjm@see_my_sig_for_address.com 2005-10-01, 10:21 am |
| Do not cross-post this shit to alt.hvac
On 30 Sep 2005 21:00:07 -0700, "Johan" <JohanKristoff@hotmail.com>
wrote:
>Hello,
>I'm about to make a big decision regarding installation of a ground
>source heat pump (closed loop wells) and a traditional hydro air/boiler
>oil-fire system. I'm looking for some advice/comments regarding the
>assumptions/calcs. that I've made regarding cost savings. Here goes:
>1. Southern New England temps.
>2. heat loss calcs from me and others confirms about 85000 Btu/hr
>3. Oil: $2.25/gal, furnace efficiency .85, $19/MBtu
>4. Ground source heat pump: $.096/kWh, COP 4.1, $6.92/MBtu
>5. 175MBtu/year <---is this right? This is roughly based on my previous
>experience with an oil system scaled up for difference in square
>footage between the homes. I realize this is VERY inaccurate. What
>more information do I REASONABLY need for a more accurate number? Is
>there an equation/rule of thumb?
>6. Therefore, for savings calcs, Oil heat costs $3300/year and GSHP
>heat costs $1200/year
>8. $25000 (quoted) additional cost of GSHP over Oil, 11 to 12 years
>payback of investment.
>
>Any comments/suggestions are greatly appreciated as this is a really
>big decision.
>Thanks
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/
| |
| Solar Flare 2005-10-01, 12:21 pm |
| Do not cross-post your shit to alt.energy.homepower
<pjm@see_my_sig_for_address.com> wrote in message
news:u42tj1dq0mvof5nlmfjckhf8p3rhcsqgot@4ax.com...
Do not cross-post this shit to alt.hvac
On 30 Sep 2005 21:00:07 -0700, "Johan" <JohanKristoff@hotmail.com>
wrote:
>Hello,
>I'm about to make a big decision regarding installation of a ground
>source heat pump (closed loop wells) and a traditional hydro air/boiler
>oil-fire system. I'm looking for some advice/comments regarding the
>assumptions/calcs. that I've made regarding cost savings. Here goes:
>1. Southern New England temps.
>2. heat loss calcs from me and others confirms about 85000 Btu/hr
>3. Oil: $2.25/gal, furnace efficiency .85, $19/MBtu
>4. Ground source heat pump: $.096/kWh, COP 4.1, $6.92/MBtu
>5. 175MBtu/year <---is this right? This is roughly based on my previous
>experience with an oil system scaled up for difference in square
>footage between the homes. I realize this is VERY inaccurate. What
>more information do I REASONABLY need for a more accurate number? Is
>there an equation/rule of thumb?
>6. Therefore, for savings calcs, Oil heat costs $3300/year and GSHP
>heat costs $1200/year
>8. $25000 (quoted) additional cost of GSHP over Oil, 11 to 12 years
>payback of investment.
>
>Any comments/suggestions are greatly appreciated as this is a really
>big decision.
>Thanks
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/
| |
| nicksanspam@ece.villanova.edu 2005-10-01, 12:21 pm |
| <pjm@see_my_sig_for_address.com> wrote:
>Do not cross-post this shit to alt.hvac
Sez who? :-)
Nick
| |
| Jonathan Grobe 2005-10-01, 12:21 pm |
| On 2005-10-01, Johan <JohanKristoff@hotmail.com> wrote:
> Hello,
> I'm about to make a big decision regarding installation of a ground
> source heat pump (closed loop wells) and a traditional hydro air/boiler
> oil-fire system. I'm looking for some advice/comments regarding the
> assumptions/calcs. that I've made regarding cost savings. Here goes:
> 1. Southern New England temps.
> 2. heat loss calcs from me and others confirms about 85000 Btu/hr
> 3. Oil: $2.25/gal, furnace efficiency .85, $19/MBtu
> 4. Ground source heat pump: $.096/kWh, COP 4.1, $6.92/MBtu
A big question is what is going to be the price of heating oil
and electricity 5 years from now, 10 years from now, 20 years from
now? Are they both to increase in price roughly comparable to
inflation rates? Is heating oil at a cyclical peak and will now go
down or is peak oil finally happening with vast increases in heating
oil prices on the way? What sources does your electric company use
to generate heat? What will happen there?
--
Jonathan Grobe Books
Browse our inventory of thousands of used books at:
http://www.grobebooks.com
| |
|
|
"Jonathan Grobe" <grobe@netins.net> wrote in message
news:slrndjt9ah.vbk.grobe@worf.netins.net...
> On 2005-10-01, Johan <JohanKristoff@hotmail.com> wrote:
>
> A big question is what is going to be the price of heating oil
> and electricity 5 years from now, 10 years from now, 20 years from
> now? Are they both to increase in price roughly comparable to
> inflation rates? Is heating oil at a cyclical peak and will now go
> down or is peak oil finally happening with vast increases in heating
> oil prices on the way? What sources does your electric company use
> to generate heat? What will happen there?
>
> --
> Jonathan Grobe Books
> Browse our inventory of thousands of used books at:
> http://www.grobebooks.com
>
I would imagine that electricity and gas will increase in price at
least at the nominal inflation rate over the next 10 years. Natural
gas has more than doubled in price in California since they deregulated
it maybe 10 years ago. That would put the increase higher than inflation.
| |
| Power's Mechanical 2005-10-01, 3:21 pm |
| <pjm@see_my_sig_for_address.com> wrote:
>Do not cross-post this shit to alt.hvac
Sez who? :-)
Nick
xxxx
No one of any importance. Lippy is just some flaming forging
blackmailing spammer who thinks his shit dont stink.
| |
|
|
"Power's Mechanical" <pusher100@hotmail.com> wrote in message
news:1128187155.859131.170350@f14g2000cwb.googlegroups.com...
> <pjm@see_my_sig_for_address.com> wrote:
>
>
> Sez who? :-)
>
> Nick
>
> xxxx
>
> No one of any importance. Lippy is just some flaming forging
> blackmailing spammer who thinks his shit dont stink.
>
Maybe alt.hvac does not like solar. Could be why the legislation
was held up on California solar roofs. With a larger view and a bit
of training the HVAC people could make lots of money installing
solar. Just a bit of adjustment that may be good for all of us.
| |
|
|
"Johan" <JohanKristoff@hotmail.com> wrote in message
news:1128139207.741966.97150@z14g2000cwz.googlegroups.com...
> Hello,
> I'm about to make a big decision regarding installation of a ground
> source heat pump (closed loop wells) and a traditional hydro air/boiler
> oil-fire system. I'm looking for some advice/comments regarding the
> assumptions/calcs. that I've made regarding cost savings. Here goes:
> 1. Southern New England temps.
> 2. heat loss calcs from me and others confirms about 85000 Btu/hr
> 3. Oil: $2.25/gal, furnace efficiency .85, $19/MBtu
> 4. Ground source heat pump: $.096/kWh, COP 4.1, $6.92/MBtu
> 5. 175MBtu/year <---is this right? This is roughly based on my previous
> experience with an oil system scaled up for difference in square
> footage between the homes. I realize this is VERY inaccurate. What
> more information do I REASONABLY need for a more accurate number? Is
> there an equation/rule of thumb?
> 6. Therefore, for savings calcs, Oil heat costs $3300/year and GSHP
> heat costs $1200/year
> 8. $25000 (quoted) additional cost of GSHP over Oil, 11 to 12 years
> payback of investment.
>
> Any comments/suggestions are greatly appreciated as this is a really
> big decision.
> Thanks
>
The problem is you need a 1 ton unit for each 250 ft. bore hole which will
yield 12,000 btu's. so you need 7 bore holes and a 7 ton unit to get 85,000
btu's. If you need 120,000 btu's you need 10 bore holes and a 10 ton unit.
Now that will take a great deal of electricity.
| |
|
| good thoughts so far.
As Nick asked, where does the 85000 BTU/hr come from? Is that a peak
load or a typical one?
is this a new house or an existing one? If it's existing, what do you
have now?
If it's a new one, then you can build the cost into the mortgage and
make it much less painful. In fact, I've seen analysis that show it to
reduce your payments because of the savings.
In my house in PA, I was going through several fill-ups of dual tanks
(~500 gallons/fill) with oil heat used for water and heat. I installed
a geothermal last winter and used the oil as backup heat for cold days
(<~15-20F) and the geothermal the rest of the year. I also got rid of
my old "high efficiency" 5-ton Carrier A/C system (~10 SEER).
This summer, my electric usage was down about 25% from last year in
spite of higher average temperatures. Last winter was very cold and the
geothermal was running 10-20 hours/day and the oil 1-5 hours/day during
January to avoid stressing the loop field too much.
I ended up using about 1 fill of oil 500 gallons, instead of 3 fills
AND my electric bills were lower! The reason my electric bills were
lower is because in PA, we get a discount for electric heat, so my kwh
charge is dramatically lower in the winter. My net savings then is
about 1000 gallons of oil and ~30% in electric bills. Back of the
envelope savings then are about $3000/year.
My system is a 4-ton system.
In addition, I've also spent the year doing as much as feasible to make
my house more efficient. lots more insulation in the attic. Low-e
windows. Air sealing every penetration I can find. I'm getting
dense-pack cellulose in the walls and cathedral ceilings next week.
Note - if I were to do it again here in PA, I'd go for a high
efficiency conventional heat pump. The reason is this - in my area,
since the balance point for my system is ~15F, a good two stage heat
pump(i.e. Lennox XP19) with oversized heating could have a balance
point into the low 20's and work efficiently in the summer, so there's
not much difference there. And instead of paying $20k for the
geothermal install, the heat pump might be $7k. That's a lot of saving
to apply towards the incrementally greater energy costs.
The efficiency of the conventional HP won't be quite as good for the
coldest and hottest months, but in your area, you'll probably run 9-10
months at about the same efficiency as the geothermal system. Keep in
mind, while the companies will make claims based on your ground
temperature of ~50F, as soon as your system runs in the winter, the
ground temp will drop. I installed temperature probes along with my
loops and monitored ground temp all winter. My loops were operating
below freezing much of the winter so system output and efficiency was
far less than rated.
Just some more food for thought.
| |
| Duane C. Johnson 2005-10-01, 10:21 pm |
| Hi Nog;
Nog wrote:
> "Johan" <JohanKristoff@hotmail.com> wrote:
> The problem is you need a 1 ton unit for each 250 ft. bore
> hole which will yield 12,000 btu's.
Do you really mean to say that that bore hole can
only deliver 12,000 btu's.
Heck, my furnace can deliver 10 times that amount
every hour. And your bore hole has a lifetime limit
of 12,000 btu's.
That's not very much?
> so you need 7 bore holes and a 7 ton unit to get 85,000
> btu's.
Are you sure con only get 85,000 btu's?
> If you need 120,000 btu's you need 10 bore holes and a
> 10 ton unit. Now that will take a great deal of electricity.
That's not very much electricity?
Oh, I understand.
You don't know the difference between energy and power!
Never mind!!!!
Duane
--
Home of the $35 Solar Tracker Receiver
http://www.redrok.com/led3xassm.htm [*]
Powered by \ \ \ //|
Thermonuclear Solar Energy from the Sun / |
Energy (the SUN) \ \ \ / / |
Red Rock Energy \ \ / / |
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| |
| geoman jr 2005-10-01, 10:21 pm |
|
"Astro" <tedinoue@gmail.com> wrote in message
news:1128204929.873176.7020@o13g2000cwo.googlegroups.com...
> good thoughts so far.
> As Nick asked, where does the 85000 BTU/hr come from? Is that a peak
> load or a typical one?
> is this a new house or an existing one? If it's existing, what do you
> have now?
> If it's a new one, then you can build the cost into the mortgage and
> make it much less painful. In fact, I've seen analysis that show it to
> reduce your payments because of the savings.
> In my house in PA, I was going through several fill-ups of dual tanks
> (~500 gallons/fill) with oil heat used for water and heat. I installed
> a geothermal last winter and used the oil as backup heat for cold days
> (<~15-20F) and the geothermal the rest of the year. I also got rid of
> my old "high efficiency" 5-ton Carrier A/C system (~10 SEER).
> This summer, my electric usage was down about 25% from last year in
> spite of higher average temperatures. Last winter was very cold and the
> geothermal was running 10-20 hours/day and the oil 1-5 hours/day during
> January to avoid stressing the loop field too much.
> I ended up using about 1 fill of oil 500 gallons, instead of 3 fills
> AND my electric bills were lower! The reason my electric bills were
> lower is because in PA, we get a discount for electric heat, so my kwh
> charge is dramatically lower in the winter. My net savings then is
> about 1000 gallons of oil and ~30% in electric bills. Back of the
> envelope savings then are about $3000/year.
> My system is a 4-ton system.
> In addition, I've also spent the year doing as much as feasible to make
> my house more efficient. lots more insulation in the attic. Low-e
> windows. Air sealing every penetration I can find. I'm getting
> dense-pack cellulose in the walls and cathedral ceilings next week.
>
> Note - if I were to do it again here in PA, I'd go for a high
> efficiency conventional heat pump. The reason is this - in my area,
> since the balance point for my system is ~15F, a good two stage heat
> pump(i.e. Lennox XP19) with oversized heating could have a balance
> point into the low 20's and work efficiently in the summer, so there's
> not much difference there. And instead of paying $20k for the
> geothermal install, the heat pump might be $7k. That's a lot of saving
> to apply towards the incrementally greater energy costs.
>
> The efficiency of the conventional HP won't be quite as good for the
> coldest and hottest months, but in your area, you'll probably run 9-10
> months at about the same efficiency as the geothermal system. Keep in
> mind, while the companies will make claims based on your ground
> temperature of ~50F, as soon as your system runs in the winter, the
> ground temp will drop. I installed temperature probes along with my
> loops and monitored ground temp all winter. My loops were operating
> below freezing much of the winter so system output and efficiency was
> far less than rated.
>
Astro you paid 20,000 $ for a four ton geothermal system and you need to use
oil for a backup system?? Sounds like your installer fucked you on the loop
sizing to save himself some money. Doesn't your geo have electric strips for
backup?? Also if your system was sized for your house prior to your
insulating it and you put in a bunch more be prepared to be uncomfortable in
the next cooling cycle. Optimal loop efficiency is usually not optained
until the second year of operation so you should see aditional savings then
if it was properly designed. Oh, because of coil designs, air to air heat
pumps ( except trane and american standard) lose their efficiency within a
short period of time and become even less so if not properly cleaned and
serviced regularly (maintainence). With a geo a home owner basicaly just has
to make sure he keeps the filter changed regularly. Service is usually just
a quick check of loop pressures and temps and the electical side components.
We install high efficiency filters so coil cleaning is usually not a problem
= additional savings. Your loop if properly designed and sized should see
below freezing temps only in late winter months and usually those that have
been colder than normal.
> Just some more food for thought.
>
| |
| PrecisionMachinisT 2005-10-02, 12:21 am |
|
"Nog" <nognog@adelphia.net> wrote in message
news:aN2dnWqXu50rbKPeRVn-pQ@adelphia.com...
>
> "Johan" <JohanKristoff@hotmail.com> wrote in message
> news:1128139207.741966.97150@z14g2000cwz.googlegroups.com...
> The problem is you need a 1 ton unit for each 250 ft. bore hole which will
> yield 12,000 btu's. so you need 7 bore holes and a 7 ton unit to get
85,000
> btu's. If you need 120,000 btu's you need 10 bore holes and a 10 ton unit.
Much depends upon actual bore spacing and the soil thermal transfer
characteristics ......consider vertical loops set in a sandy aquifer--with a
water table that's always moving downstream, for instance...
> Now that will take a great deal of electricity.
Still, it would cost him one hell of a lot less in electricity than if he
was to be running straight heat strips.....
--
SVL
| |
| tedinoue@gmail.com 2005-10-02, 3:21 am |
| Geoman - you got that right! Remember, I'm the one who bitched last
winter because my installer was a f*ckwad and installed the vertical
loops too close together, put in too few loops and generally hacked the
entire install. They are no longer representing that geothermal
company...
OTOH, the system was designed to be somewhat undersized for winter so
that the Summer dehumidification would be satisfactory. The installer
wanted to install a 5-ton system which really would have sucked during
the summer. Oil is the backup because it was already in the house and
used for a zone that the geo system doesn't reach. I could say more but
I don't want to hijack the OP's thread any more.
Your comments are exactly why I asked the OP for more info on their
home and load calcs. If they put in a single stage system designed for
heating 85k BTU/hr, they're going to really suffer during the summer.
I would think the best case for them would be a two stage geo system.
If they're lucky, they're home is over an active aquifer with plenty of
water movement.
| |
| PrecisionMachinisT 2005-10-02, 4:21 am |
|
<tedinoue@gmail.com> wrote in message
news:1128233389.820624.128910@g14g2000cwa.googlegroups.com...
> Geoman - you got that right! Remember, I'm the one who bitched last
> winter because my installer was a f*ckwad and installed the vertical
> loops too close together, put in too few loops and generally hacked the
> entire install. They are no longer representing that geothermal
> company...
>
> OTOH, the system was designed to be somewhat undersized for winter so
> that the Summer dehumidification would be satisfactory. The installer
> wanted to install a 5-ton system which really would have sucked during
Then curious....just how big a system did YOU have him install ???
> the summer. Oil is the backup because it was already in the house and
> used for a zone that the geo system doesn't reach. I could say more but
> I don't want to hijack the OP's thread any more.
>
> Your comments are exactly why I asked the OP for more info on their
> home and load calcs. If they put in a single stage system designed for
> heating 85k BTU/hr, they're going to really suffer during the summer.
>
Generally, you're gonna either lose or gain "some amount" of heat, into the
loop--computed on an adjusted yearly basis, and how much all depends on
average soil temp, soil thermal conduction rate, available soil mass, and
your average yearly outdoors ambient temp...
>
> I would think the best case for them would be a two stage geo system.
>
I would think then you should shut the fuck up now, as it's readily apparent
you still haven't even a fucking clue one.
>
> If they're lucky, they're home is over an active aquifer with plenty of
> water movement.
>
Even luckier would be to have an underground water source at 72
degF........lets face it--then no heat pump would be needed at all, eh ???
--
SVL
| |
|
|
"Duane C. Johnson" <redrok@redrok.com> wrote in message
news:433F31BD.8010500@redrok.com...
> Hi Nog;
>
> Nog wrote:
>
>
> Do you really mean to say that that bore hole can
> only deliver 12,000 btu's.
> Heck, my furnace can deliver 10 times that amount
> every hour. And your bore hole has a lifetime limit
> of 12,000 btu's.
>
> That's not very much?
>
>
> Are you sure con only get 85,000 btu's?
>
>
> That's not very much electricity?
>
> Oh, I understand.
> You don't know the difference between energy and power!
>
> Never mind!!!!
>
> Duane
¶ I guess you don't know what a heat pump is! §
Nor what one ton-hour of refrigeration is!
> Home of the $35 Solar Tracker Receiver
> http://www.redrok.com/led3xassm.htm [*]
> Powered by \ \ \ //|
> Thermonuclear Solar Energy from the Sun / |
> Energy (the SUN) \ \ \ / / |
> Red Rock Energy \ \ / / |
> Duane C. Johnson Designer \ \ / \ / |
> 1825 Florence St Heliostat,Control,& Mounts |
> White Bear Lake, Minnesota === \ / \ |
> USA 55110-3364 === \ |
> (651)426-4766 use Courier New Font \ |
> redrok@redrok.com (my email: address) \ |
> http://www.redrok.com (Web site) ===
| |
| tedinoue@gmail.com 2005-10-02, 11:21 am |
| I spec'd a 4-ton system with a minimum of 600 ft of bores, but
preferably 800 ft based on my local geologic conditions (solid diabase
intrusion) and minimal water migration. Based on my winter
measurements, this would have been an excellent choice. The problem is,
as you know, if the loop field is too small, the winter ground
temperature will drop too quickly, unable to recover from the load,
resulting in a reduced system output
| |
| tedinoue@gmail.com 2005-10-02, 11:21 am |
| as I was saying, with too small a loop field, the ground temperature
won't be able to recover fast enough to keep up with the load, and
system output will decrease, as it did.
The point is, the OP needs to be very cognizant of the installation
size and ensure that the loop field is adequate.
Moreover, they need to balance the tendancy to oversize the system with
a desire to properly dehumidify during the summer. The typical "2x
heating capacity as cooling" that many endorse will lead to
uncomfortable summers.
OTOH, if you use a two-stage or otherwise variable capacity system, you
get the best of both worlds - enough capacity during the winter and
long run humidity removal during the summer.
As the OP indicated, this is a really big decision for them and they
need information on which to evaluate the systems. I'm showing how it's
far more complex than simply getting enough BTUs to cover peak demand,
especially where geo systems are concerned.
| |
| PrecisionMachinisT 2005-10-02, 2:21 pm |
|
<tedinoue@gmail.com> wrote in message
news:1128261078.740920.170060@g49g2000cwa.googlegroups.com...
> as I was saying, with too small a loop field, the ground temperature
> won't be able to recover fast enough to keep up with the load, and
> system output will decrease, as it did.
> The point is, the OP needs to be very cognizant of the installation
> size and ensure that the loop field is adequate.
> Moreover, they need to balance the tendancy to oversize the system with
> a desire to properly dehumidify during the summer. The typical "2x
> heating capacity as cooling" that many endorse will lead to
> uncomfortable summers.
> OTOH, if you use a two-stage or otherwise variable capacity system, you
> get the best of both worlds - enough capacity during the winter and
> long run humidity removal during the summer.
>
If you are running a lower capacity cooling stage during summer with a
marginally sized loop field installed then your yearly net heat loss is
steadily increased, quite possibly to the point where 'all hell freezes
over' when an especially cold winter occurs.
>
> As the OP indicated, this is a really big decision for them and they
> need information on which to evaluate the systems. I'm showing how it's
> far more complex than simply getting enough BTUs to cover peak demand,
> especially where geo systems are concerned.
>
--
SVL
| |
| tedinoue@gmail.com 2005-10-02, 2:21 pm |
| What's the alternative? In a heating dominated climate, regardless of
system sizing, you're going to lower the ground temperature. The only
hope is that the thermal diffusivity and large scale ground thermal
mass is high enough that during the summer the loop field temperature
fully restores.
The problem is the undersized loop field will always draw down too
quickly and provide unacceptable performance during extended periods of
cold. And without support of the manufacturer/installer, I have to work
around those limitations.
| |
| PrecisionMachinisT 2005-10-02, 3:21 pm |
|
<tedinoue@gmail.com> wrote in message
news:1128272829.111745.102930@z14g2000cwz.googlegroups.com...
> What's the alternative? In a heating dominated climate, regardless of
> system sizing, you're going to lower the ground temperature. The only
> hope is that the thermal diffusivity and large scale ground thermal
> mass is high enough that during the summer the loop field temperature
> fully restores.
Intentionally ADD heat to the loop during the late summertime, by whatever
means available.....and just realize that if your operating a multi staged
unit at a reduced capacity during the cooling season you're essentially
doing exactly the opposite.
> The problem is the undersized loop field will always draw down too
> quickly and provide unacceptable performance during extended periods of
> cold. And without support of the manufacturer/installer, I have to work
> around those limitations.
As a homeowner, I would probly then consider installing a pellet stove or
somesuch.
===
At any rate, I'm done here...
Most of the above doesn't even apply to my own particular case anyways,
being's as I'm currently using open loop geo mostly just to supplement an
existing air source heat pump during the occasional cold snap that we get
here in the pacific northwest.
And good luck with your own setup.
--
SVL
| |
| Geoman1 2005-10-02, 11:21 pm |
|
"Astro" <tedinoue@gmail.com> wrote in message
news:1128204929.873176.7020@o13g2000cwo.googlegroups.com...
> good thoughts so far.
> As Nick asked, where does the 85000 BTU/hr come from? Is that a peak
> load or a typical one?
> is this a new house or an existing one? If it's existing, what do you
> have now?
> If it's a new one, then you can build the cost into the mortgage and
> make it much less painful. In fact, I've seen analysis that show it to
> reduce your payments because of the savings.
> In my house in PA, I was going through several fill-ups of dual tanks
> (~500 gallons/fill) with oil heat used for water and heat. I installed
> a geothermal last winter and used the oil as backup heat for cold days
> (<~15-20F) and the geothermal the rest of the year. I also got rid of
> my old "high efficiency" 5-ton Carrier A/C system (~10 SEER).
> This summer, my electric usage was down about 25% from last year in
> spite of higher average temperatures. Last winter was very cold and the
> geothermal was running 10-20 hours/day and the oil 1-5 hours/day during
> January to avoid stressing the loop field too much.
> I ended up using about 1 fill of oil 500 gallons, instead of 3 fills
> AND my electric bills were lower! The reason my electric bills were
> lower is because in PA, we get a discount for electric heat, so my kwh
> charge is dramatically lower in the winter. My net savings then is
> about 1000 gallons of oil and ~30% in electric bills. Back of the
> envelope savings then are about $3000/year.
> My system is a 4-ton system.
> In addition, I've also spent the year doing as much as feasible to make
> my house more efficient. lots more insulation in the attic. Low-e
> windows. Air sealing every penetration I can find. I'm getting
> dense-pack cellulose in the walls and cathedral ceilings next week.
>
> Note - if I were to do it again here in PA, I'd go for a high
> efficiency conventional heat pump. The reason is this - in my area,
> since the balance point for my system is ~15F, a good two stage heat
> pump(i.e. Lennox XP19) with oversized heating could have a balance
> point into the low 20's and work efficiently in the summer, so there's
> not much difference there. And instead of paying $20k for the
> geothermal install, the heat pump might be $7k. That's a lot of saving
> to apply towards the incrementally greater energy costs.
I don't know where your going to get a two stage heat pump installed for
$7K.
>
> The efficiency of the conventional HP won't be quite as good for the
> coldest and hottest months, but in your area, you'll probably run 9-10
> months at about the same efficiency as the geothermal system. Keep in
> mind, while the companies will make claims based on your ground
> temperature of ~50F, as soon as your system runs in the winter, the
> ground temp will drop. I installed temperature probes along with my
> loops and monitored ground temp all winter.
Why install probes along with the loops? Just leave a thermometer in the
access plugs, the ground isn't going to get any colder than the solution
going through it.
My loops were operating
> below freezing much of the winter so system output and efficiency was
> far less than rated.
Then they screwed you on the loop size, the biggest problem I have with the
competition! My loops seldom go below freezing. Imagine if you hired a
competant installer.
>
> Just some more food for thought.
>
| |
| Geoman1 2005-10-03, 12:21 am |
|
"PrecisionMachinisT" <precisionmachinist@hotmail.com> wrote in message
news:8NWdnUTPrptFl93eRVn-qg@scnresearch.com...
>
> <tedinoue@gmail.com> wrote in message
> news:1128261078.740920.170060@g49g2000cwa.googlegroups.com...
>
> If you are running a lower capacity cooling stage during summer with a
> marginally sized loop field installed then your yearly net heat loss is
> steadily increased, quite possibly to the point where 'all hell freezes
> over' when an especially cold winter occurs.
That would have to be a major undesized loop system for this to happen. On
a horizontal loop, being no lower than 8 feet, the loop recovers due to
solar and sensible gains as stated by O.S.U. and others. The Geothermal
Heat Pump Constortium stated, and I was surprised when I learned this:
" In winter, the ground soaks up solar energy and provides a barrier to cold
air. "
http://www.geoexchange.org/about/how.htm
Another article I once had, and will look for, gave the percentage of this
solar gain. I once heard Phil Rawlings teach about problems associated with
horizontal loops for cooling that are installed under asphalt parking lots
if the solar gain isn't factored in. Even a yard absorbs solar gains.
I think we can agree, most loops are not installed to the maximum efficiency
of the unit but most are grossly undersized. This is where the contractor
makes his money, by ripping off the customer. The customer swith's from
propane to Geothermal and saves some money and the customer is all happy,
not knowing that the 3.27 COP geothermal system he bought is only putting
out 2.4 or even worse! And in our area resistant heat is now cheaper than
natural gas, so the customers bill will always show a lower utility bill,
and they think the other contractor who was going to install an extra 1000
feet of loop and charge $2000 more was the crook!!
>
> --
>
> SVL
>
>
| |
| Abby Normal 2005-10-03, 12:21 am |
| GEO
If memory serves me correct, I think Astro had boreholes in solid
granite Geoman plus it is a dx system
| |
| jkristoff8387 2005-10-03, 1:21 am |
| These are great questions; some of which I have considered. Of course,
I can only speculate what will happen to the price of energy. Here in
New England, the price of electricity has been pretty stable over the
last two decades. Oil has swung widely in the same time period.
Granted, California has seen on rather dramatic changes in its
electricity prices and I suppose the same could happen here.
| |
| jkristoff8387 2005-10-03, 1:21 am |
| >From my understanding, loop sizing is very much dependent on the soil
conditions. My proposed well field will be located near a wetlands
area that remains "wet" for most of the year. Would this be considered
a good location? Would a vertical loop well that contains aquafer
water be better than a grouted well? Do they grout all wells if there
is water found?
I would like to prevent my installer from undersizing the loops to his
advantage. Can I specify the work in such a way that he can not cheat?
iFor example: "the system must perform to such and such a
specification"...."water loop exit temperatures must remain such and
such for given environmental conditions" Or will he run for the hills
when I tell him this? Also, he could properly size the loops and
undersize the equipment (thereby also cheating). This would be just as
bad, because the backup electric heat would kick in. How can I specify
his work so that these things don't happen to me?
| |
| jkristoff8387 2005-10-03, 1:21 am |
| Another question, how can you improve on the thermal conductivity of
the vertical borehole? Is there any other reliable tubing material
with better thermal conductivity than the regular black plastic well
pipe? To grout or not to grout?
Also, is there a cheap way to determine the best location for the well
field? What types of soil conditions? During the foundation
excavation, I had quite a bit of water coming into the pit and my
neighbor had even more. Is this a good sign for loop performance?
| |
| tedinoue@gmail.com 2005-10-03, 6:21 am |
| Correct. Mine was a challenging install. I repeatedly questioned the
installer and manufacturer on loop field size prior to and after the
installation, and they insisted on 100ft/ton.
The installer came highly recommended by the vendor, which is why I
went with them. The vendor said that this particular installer was so
good that they sent him around to help out installers in other regions.
What a load that was...
I did have a document for them to sign stating that they ensured that
the system would work through winter without freezing up and system
would operate to spec over several seasons.
Several grand later in legal fees, I'm no better off and have been
talking with other installers about custom mods they can do to help.
But back to the OP...
[color=darkred]
area that remains "wet" for most of the year. Would this be considered
a good location? Would a vertical loop well that contains aquafer
water be better than a grouted well? Do they grout all wells if there
is water found?
<<
Grouting depends on local codes.
The performance of a system in the conditions you describe could be
very good with that much water. The water will allow very efficient
thermal transfer from the ground loops. As the water migrates, it will
carry away the heat, probably much more effectively than simple thermal
diffusion.
The other thing, with that much water around, if conditions permit, you
might consider going open loop. An open loop system will provide you
with most stable operating water temperatures because you're constantly
bringing in new water at ambient ground temperature. You can have other
problems however, such as scaling, which will reduce the reliability of
the system. Plus, local codes again come into play as they're afraid of
people contaminating the aquifer.
Overall, it seems like there's a good chance that you're in a position
to have excellent long term performance.
| |
|
|
| Abby Normal 2005-10-03, 9:21 am |
| Your direct loops would be below freezing. A system that circulates
water/antifeeze would have its loops close to freezing, the refrigerant
system would have to be colder than this, to extract heat and would
therefore operate below freezing.
Wet soils are excellent, the main reason being there is 144 Btu/lb of
water available as the latent heat of fusion.
tedinoue@gmail.com wrote:
> Correct. Mine was a challenging install. I repeatedly questioned the
> installer and manufacturer on loop field size prior to and after the
> installation, and they insisted on 100ft/ton.
> The installer came highly recommended by the vendor, which is why I
> went with them. The vendor said that this particular installer was so
> good that they sent him around to help out installers in other regions.
> What a load that was...
> I did have a document for them to sign stating that they ensured that
> the system would work through winter without freezing up and system
> would operate to spec over several seasons.
> Several grand later in legal fees, I'm no better off and have been
> talking with other installers about custom mods they can do to help.
> But back to the OP...
>
> area that remains "wet" for most of the year. Would this be considered
>
> a good location? Would a vertical loop well that contains aquafer
> water be better than a grouted well? Do they grout all wells if there
> is water found?
> <<
> Grouting depends on local codes.
> The performance of a system in the conditions you describe could be
> very good with that much water. The water will allow very efficient
> thermal transfer from the ground loops. As the water migrates, it will
> carry away the heat, probably much more effectively than simple thermal
> diffusion.
>
> The other thing, with that much water around, if conditions permit, you
> might consider going open loop. An open loop system will provide you
> with most stable operating water temperatures because you're constantly
> bringing in new water at ambient ground temperature. You can have other
> problems however, such as scaling, which will reduce the reliability of
> the system. Plus, local codes again come into play as they're afraid of
> people contaminating the aquifer.
> Overall, it seems like there's a good chance that you're in a position
> to have excellent long term performance.
| |
| Abby Normal 2005-10-03, 9:21 am |
| Astro
Other than having the experience of your own DX system that does not
work that well, you are not the best qualified to give anyone else
advise, except to avoid your type of installation.
| |
| Geoman1 2005-10-03, 10:21 am |
|
"jkristoff8387" <JohanKristoff@hotmail.com> wrote in message
news:1128310591.051111.110280@g43g2000cwa.googlegroups.com...
> conditions. My proposed well field will be located near a wetlands
> area that remains "wet" for most of the year. Would this be considered
> a good location? Would a vertical loop well that contains aquafer
> water be better than a grouted well? Do they grout all wells if there
> is water found?
> I would like to prevent my installer from undersizing the loops to his
> advantage. Can I specify the work in such a way that he can not cheat?
> iFor example: "the system must perform to such and such a
> specification"...."water loop exit temperatures must remain such and
> such for given environmental conditions" Or will he run for the hills
> when I tell him this? Also, he could properly size the loops and
> undersize the equipment (thereby also cheating). This would be just as
> bad, because the backup electric heat would kick in. How can I specify
> his work so that these things don't happen to me?
Demand that they PROVIDE YOU A COPY of a REAL computer program such as
Elite or WrightSoft that actually shows the equipment being used, the soil
conditions, the COP and EER of the unit at specific loop lengths, specifics
of the loop such as length, depth, width, size of pipe, percentage of
antifreeze and a layout, one pipe, two pipe etc etc. The program will
actually show ALL these facts. Then YOU can choose what you want to spend
and not the installer! You will pay more for a loop with 2000 feet of
excavating than 600 feet. You will pay more for 1-1/4 inch pipe over 3/4
inch. This program isn't cheap but it works. This 600 feet per ton is pure
BS all the way. For some systems its fine but for many its terribly short.
For vertical they don't want to spread out the distance over the field, like
it costs to much to hook up or to move the rigs. This is one of the biggest
problems I have seen. The 400ft per ton rule was a rule of thumb when the
factories didn't know how to really explain without calculus how to size a
loop. It used to be 400 feet per ton when I first started installing Geo's,
now some in my area is doing 600. But area of square feet that the pipe
contacts is just as important as the amount of pipe. 1000 feet of pipe in a
in a 20 foot x 3 ft trench won't work either. BTW, I ran the numbers many
times, and the 600 feet for slinkies has NEVER provided enough BTU's to
match any equipments actual COP in heating. It match's the EER of cooling
but not the heating.
Let me post a job we did this last fall, a five ton system, we used
5 Ton two stage FHP geothermal installed in clay conditions, three parallel
loops with 3/4 pipe, 7 feet deep by 2.5 feet wide, 15 feet between
trenches. The trench's were dug five feet deep and the general was bring two
feet of soil in, making the job 7 feet. 15% methanol.
Total installed pipe in trench's 3000 feet, total trenching 3000 feet PLUS
the header pipe.
Equipment COP 3.46. Our equipment 3.42, a loss of 1,157 BTUs in the worse
conditions.
The same system using a slinky and 'rule of thumbs' would be:
Equipment COP 3.46, Actual COP with the slinky rule of thumb, 3.04
Required BTU 44899, Actual 32155
Entering water temperature Desired 27F ACTUAL 11F.
In all fairness,to get the COP's up to the manufacturers rating would
require 8079 feet of pipe, much too costly. But, if the trench was wider or
longer the system would require less pipe. There is also a balance point as
to when its cheaper to run resistance instead of putting in such a large
loop. But usually I don't see a loop installed that's even close to what's
required, and this is from 'professional loop companies'
I lost a job to a company who was $3000 less than us. We were to install
2400 ft of 3/4 in six trenches 200 feet long. The competitor put in four
loops at 50 feet. You do the math on both soil contact and costs factors. If
anything, I wasn't charging enough. The customer will NEVER know what his
actually energy costs would be. I don't have the numbers any longer but they
were short even in the cooling season, running the amps and run time up on
the system. The also ended up putting in an auxiliary Trane Heat pump in
this house for upstairs!!! The Geo was sized for the home correctly but the
loop sucked!
There are times when costs prohibit the matching of the loop to the units
COP, sometimes you will never get back the cost of the extra amount of loop,
but this is the customers decision and not the contractors. I have YET to
find a local contractor not steal from a customer when it comes to the loop,
the customer has no idea of what amount should go in, they are like sheep
going to the slaughter!! It like the service tech who adds a few pounds of
refrigerant to the bill.
Therefore, if you don't want to be cheated demand a print out and break down
the costs yourself. Then watch the loop go in and make sure they are putting
it in right. We are certified and put our own loops in because I was so
disappointed with the 'experts' screwing up our jobs. I have yet to find a
vertical loop company that is educated enough in our area. I think they all
slept through the IGSHPA courses.
Rich
| |
| Geoman1 2005-10-03, 10:21 am |
|
"Abby Normal" <a_bee_normal@yahoo.com> wrote in message
news:1128308967.469069.84370@o13g2000cwo.googlegroups.com...
> GEO
>
> If memory serves me correct, I think Astro had boreholes in solid
> granite Geoman plus it is a dx system
>
Your correct, now I remember this one. Heck, I would have not responded
with my post that doesn't relate to this problem if I just read the entire
thread :-('
Rich
| |
| Geoman1 2005-10-03, 11:21 am |
|
"Abby Normal" <a_bee_normal@yahoo.com> wrote in message
news:1128340589.152840.68720@g49g2000cwa.googlegroups.com...
> Your direct loops would be below freezing. A system that circulates
> water/antifeeze would have its loops close to freezing, the refrigerant
> system would have to be colder than this, to extract heat and would
> therefore operate below freezing.
This statement is 100% accurate. Ice means nothing except water is being
frozen.
The only way to know what your system is doing is to perform a performance
check.
>
> Wet soils are excellent, the main reason being there is 144 Btu/lb of
> water available as the latent heat of fusion.
>
> tedinoue@gmail.com wrote:
>
| |
| Geoman1 2005-10-03, 11:21 am |
|
<tedinoue@gmail.com> wrote in message
news:1128331674.219662.138050@f14g2000cwb.googlegroups.com...
> Here's a reference paper showing the effects of groundwater movement on
> performance if your into that:
> http://www.hvac.okstate.edu/pdfs/gwflow.pdf
>
> here's another good reference that goes into many of the topics
> discussed:
> http://www.geo4va.vt.edu/A1/A1.htm
>
> good luck. let us know how it works out.
I really enjoyed the second link, cool pics and good info.
Rich
| |
|
|
"Geoman1" <Geo1> wrote in message
news:Y4KdnepcDPIAqdzeRVn-uA@adelphia.com...
>
> <tedinoue@gmail.com> wrote in message
> news:1128331674.219662.138050@f14g2000cwb.googlegroups.com...
>
>
> I really enjoyed the second link, cool pics and good info.
>
> Rich
I guess you would need a 6000 foot bore hole for dependable heating and
cooling. If you don't strike oil, that is.
| |
|
| >>Your direct loops would be below freezing. A system that circulates
water/antifeeze would have its loops close to freezing, the refrigerant
system would have to be colder than this, to extract heat and would
therefore operate below freezing. <<
I understand that. I don't measure loop temperature, I have done
extensive measurement and analysis of ground temperature recovery when
the system is off. I also have a temperature sensor installed in a bore
hole, 50 ft. down, a distance away from the loops so that I can
monitor the ground temperature.
[color=darkred]
work that well, you are not the best qualified to give anyone else
advise, except to avoid your type of installation. <<
Largely, I agree with you, and avoid posting about things which I know
nothing about. However, the science of GSHP systems is something I've
studied to an extent that I can provide some useful theory for the OP.
If anything I've posted is erroneous/BS, please feel free to cite
specifics. The only thing I regret noting is a $ for an air source heat
pump, since obviously that amount will vary.
| |
| Pete C 2005-10-11, 1:21 pm |
| On 2 Oct 2005 10:07:09 -0700, tedinoue@gmail.com wrote:
>What's the alternative? In a heating dominated climate, regardless of
>system sizing, you're going to lower the ground temperature. The only
>hope is that the thermal diffusivity and large scale ground thermal
>mass is high enough that during the summer the loop field temperature
>fully restores.
If the weather is mild part of the time, it may be useful to have an
air coil too to minimise the loading on the ground loop. When the air
temperature is higher than the ground loop it could be used to
recharge it as well. May mitigate an undersized loop too.
I'm suprised this is not done already.
cheers,
Pete.
| |
| Philip Lewis 2005-10-11, 2:21 pm |
| Pete C <petecnews@gmail.com> writes:
>On 2 Oct 2005 10:07:09 -0700, tedinoue@gmail.com wrote:
>If the weather is mild part of the time, it may be useful to have an
>air coil too to minimise the loading on the ground loop. When the air
>temperature is higher than the ground loop it could be used to
>recharge it as well. May mitigate an undersized loop too.
heh... i thinking about this a while ago... wondering if the added
complexity would be worth it.
I thought i asked on one of the home energy newsgroups, and didn't get
a response.
--
be safe.
flip
Ich habe keine Ahnung was das bedeutet, oder vielleicht doch?
Remove origin of the word spam from address to reply (leave "+")
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