Geothermal heat pump - Anyone have one?

BretLuter · **Posted:** Wed Sep 15, 2010 1:11 pm

Frank Catena wrote:

DickRasmussen wrote:

Frank Catena wrote:

Hard to argue with that math. Congrats.

Have they estimated how much water will be required from the wells to support the heat exchanger? That seems to be the only unknown and (I guess) the driver behind the 3-4 estimate? Unfortunately it seems hard to predict how much water wells will provide until you drill.

Any thought to adding a propane fueled generator as electrical backup?

Frank

Does the well actually need to be more than "damp" to facilitate heat transfer along with the thermal grout? The loop itself is closed and presumably has some sort of non corrosive "heat transfer medium". i.e. is this more of a coolant to rock heat exchanger?

Typically two different techniques here - a true water producing well with a return well to keep the ground water resupplied. Or a closed vertical loop used when the lot size doesn't support a horizontal install. I think the rule of thumb is around 4 GPM of water (or coolant in a closed system) per ton of HVAC capacity.

Frank

Frank,

Mike said in his original post that this would be a closed loop vertical well system, so a "producing" well is not needed in this case.

I know my father in law's house had what he always called a "Florida Heat Pump" for many years, and it had a dedicated well for the system. I always thought it was wasteful because the water was never returned to the well, they just pumped it out in the drainage ditch in front of the house, or used the "waste" water to run a lawn sprinkler that ran continuously in the spring/summer months.

They had a really nice, green lawn though....

They recently replaced the system with a conventional heat pump. Not sure how it has affected their utility bills.

MikeWhitney · **Joined:** Wed Aug 20, 2003 9:15 pm **Posts:** 4724

DickRasmussen wrote:

Hi Mike,

Great analysis!!!

Thanks!

DickRasmussen wrote:

At $14K out of pocket after tax discounts, etc you probably are in the range of two heat pumps sized for your house or even my smaller house. If so, the "payback" for me might only be the need to do it before the tax benefits expire by replacing relatively new Lennox heat pumps which are 4/5 years old with R410A)

One way to look at it, the credits make geo cost about the same as a air to air system installed.

DickRasmussen wrote:

Did "they" explain the engineering basis for the 50 year in ground warranty/life expectancy and for the 30 year equipment life expectancy?

I found it's a 10 year warranty but 50 year expectancy. It's just a loop of plastic tubes cemented into the ground with DI water circulating. Guess they expect 50 years before a tube snaps or leaks.

DickRasmussen wrote:

This is a long time for many of the parts. Is there any high pressure refrigerant in the system at all or is it all relatively low pressure pumped water/heat transfer medium?

I think you found the answer. GSHPs have 2 heat exchangers: Water to freon, then freon to air. Compressor never has to work very hard with a consistent temp source.

DickRasmussen wrote:

Will the well be 800' deep? Wow (I think since my water well is about 350 feet). Where will they drill the well (i.e. near the curb)? Does the price include restoring the yard, street, driveway, etc. to pristine condition?

3x275' or so, will be on the side of my house about 15' from the foundation, right next to where the existing gaspack is. Holes need to be 10' apart.

DickRasmussen wrote:

Are you saying that operating costs (electricity for pumps and compressor, maintanance, etc.) will be between $1500 and $2000 per year including water heating with propane with the high temperature boost from the geothermal? Is this boost for cooling and heating seasons?

Yes, I expect total heat/cool/HW expense to go from about $4200 (on a bad year) to under $2k. Does not include maintenance, but from reading a lot of forums and blogs about these systems, no one has had to do any maintenance. 75% reduction for heating (compared to propane) and about 50% in cooling (air to air AC).

DickRasmussen wrote:

Are the Fed and State "discounts" actual real money (tax credits/rebates versus deductions.)? If credits/rebates what happens if tax liability is less than the discount? Do the Fed/State send a check or can it be spread over several filing years?

Read money credits with no income limitation.

DickRasmussen wrote:

Is well depth, etc. reduced it the heat/cooling load is less than yours?

Yes, it's about 150-200' per ton

DickRasmussen wrote:

Does the hot water heater desuperheater apply to electric water heaters also?

Yes, since it's a feed into the regular cold water supply line on the heater. I still have a to learn a little more about how exactly this works, since hot water will only be available when the unit is running... Not sure if it goes on demand or has a holding tank somehow.

Frank Catena · **Joined:** Wed Aug 27, 2003 1:08 pm **Posts:** 418

BretLuter wrote:

Frank Catena wrote:

DickRasmussen wrote:

Frank Catena wrote:

Hard to argue with that math. Congrats.

Have they estimated how much water will be required from the wells to support the heat exchanger? That seems to be the only unknown and (I guess) the driver behind the 3-4 estimate? Unfortunately it seems hard to predict how much water wells will provide until you drill.

Any thought to adding a propane fueled generator as electrical backup?

Frank

Does the well actually need to be more than "damp" to facilitate heat transfer along with the thermal grout? The loop itself is closed and presumably has some sort of non corrosive "heat transfer medium". i.e. is this more of a coolant to rock heat exchanger?

Typically two different techniques here - a true water producing well with a return well to keep the ground water resupplied. Or a closed vertical loop used when the lot size doesn't support a horizontal install. I think the rule of thumb is around 4 GPM of water (or coolant in a closed system) per ton of HVAC capacity.

Frank

Frank,

Mike said in his original post that this would be a closed loop vertical well system, so a "producing" well is not needed in this case.

I know my father in law's house had what he always called a "Florida Heat Pump" for many years, and it had a dedicated well for the system. I always thought it was wasteful because the water was never returned to the well, they just pumped it out in the drainage ditch in front of the house, or used the "waste" water to run a lawn sprinkler that ran continuously in the spring/summer months.

They had a really nice, green lawn though....

They recently replaced the system with a conventional heat pump. Not sure how it has affected their utility bills.

A "true" well potentially is easier and more efficient as it taps the stable ground water temps. Less efficient if you don't return the water. Closed ground loops suffer a bit because of heat transfer issues so you use more pipe (horizontal or vertical). Either way you need a certain amount of energy transfer and the amount transferred is proportional to the amount of fluid and the fluid temp delta.

Frank

Frank

Frank Catena · **Joined:** Wed Aug 27, 2003 1:08 pm **Posts:** 418

Frank Catena wrote:

BretLuter wrote:

Frank Catena wrote:

DickRasmussen wrote:

Frank Catena wrote:

Hard to argue with that math. Congrats.

Have they estimated how much water will be required from the wells to support the heat exchanger? That seems to be the only unknown and (I guess) the driver behind the 3-4 estimate? Unfortunately it seems hard to predict how much water wells will provide until you drill.

Any thought to adding a propane fueled generator as electrical backup?

Frank

Does the well actually need to be more than "damp" to facilitate heat transfer along with the thermal grout? The loop itself is closed and presumably has some sort of non corrosive "heat transfer medium". i.e. is this more of a coolant to rock heat exchanger?

Typically two different techniques here - a true water producing well with a return well to keep the ground water resupplied. Or a closed vertical loop used when the lot size doesn't support a horizontal install. I think the rule of thumb is around 4 GPM of water (or coolant in a closed system) per ton of HVAC capacity.

Frank

Frank,

Mike said in his original post that this would be a closed loop vertical well system, so a "producing" well is not needed in this case.

I know my father in law's house had what he always called a "Florida Heat Pump" for many years, and it had a dedicated well for the system. I always thought it was wasteful because the water was never returned to the well, they just pumped it out in the drainage ditch in front of the house, or used the "waste" water to run a lawn sprinkler that ran continuously in the spring/summer months.

They had a really nice, green lawn though....

They recently replaced the system with a conventional heat pump. Not sure how it has affected their utility bills.

A "true" well potentially is easier and more efficient as it taps the stable ground water temps. Less efficient if you don't return the water. Closed ground loops suffer a bit because of heat transfer issues so you use more pipe (horizontal or vertical). Either way you need a certain amount of energy transfer and the amount transferred is proportional to the amount of fluid and the fluid temp delta. Just like in a radiator,,,

Frank

Frank

DickRasmussen · **Posted:** Wed Sep 15, 2010 3:13 pm

Mike,

Thanks for the additional info. Let us know which installer you pick. Sounds like it might be worth my time to check the economics some time before the current tax credits run out in 2016 even if it means bailing out on my fairly new heat pumps. I assume that Climatemaster is the best equipment option.

DickRasmussen · **Posted:** Wed Sep 15, 2010 3:23 pm

Kind of off topic now, but my Dad used to manage a Propane company in northwestern NJ that supplied PROPANE via gas lines to the whole town. This was in the 1950's. I think the huge central distribution tanks at company's facility were supplied by rail tankers. Of course, they still had lots of delivery trucks for the other customers.

Dick

MikeWhitney · **Joined:** Wed Aug 20, 2003 9:15 pm **Posts:** 4724

FYI this is a good estimating site. I think their numbers are a bit high, but not much. Maybe I will be pleasantly surprised.

http://residential.climatemaster.com/svcalc/sc01.php

Here are my numbers. This uses $0.10/kwh and $2.34 per gal propane

DickRasmussen · **Posted:** Fri Sep 17, 2010 2:45 pm

Mike,

WOW. I see your motivation.

My house is about 2300 sq ft heated with heat pumps and electric water heater. Savings is only about $854 per year assuming their other numbers match my actual expenses. My newish heat pumps are probably around their assumed 13 SEER for standard single speed compressor efficiency units. I don't know if they assume 2 units or not.

MikeWhitney · **Joined:** Wed Aug 20, 2003 9:15 pm **Posts:** 4724

I've been busy so I haven't had a chance to update ... we're now the happy owners of geothermal heat and cooling in our house! I called our propane company to say buh-bye and burned the $800 heating bill from last year in effigy. I'll try to document here what I went through in a few sections...

First: Picking a company

Started with Local Google searches. I ended up first calling about 8 hvac companies, some who install Geo and some who don't, to get an overall feel for the market. Companies that do not install geo either didn't have anything bad to say about them, or were pretty cluleless (don't you need a pond?). I even offered to be a guinea pig for a few companies for a discount if they wanted to get into it. No takers.

From the conversations w/ the HVAC guys I found out that the wells are absolutely the most important part to get right for a vertical install. I got a handful of recommended drillers. So I cold-called about a dozen drillers from their list and the internet and asked a TON of questions. I narrowed down the list of drillers I would want to do business to about 3.

Next I went back to the three companies who seemed to be the best combination of tech knowledge, courtesy, good answers etc and had them come out. I got quotes from All American, Raleigh Heating and Air, and Boman. All 3 companies use Climatemaster, and all 3 said that the other 2 mfgrs are just as good (Waterfurnace and Florida Heat) but Climatemaster has the best local Raleigh sales, distribution, and support.

First up was Raleigh Heating and Air. They did a clean-sheet load calculation using some nice software and came up w/ 3 ton up and 2 ton down. Peter knew what he was talking about and was very thorough, and he was flexible on options, and he recommended some good details. They have only been doing geo for a year, since a guy (Brian) with a lot of experience partnered with the company.

All American did a similar visit as Raleigh but missed some details and was less flexible. They also missed some details in the load and came up with 3 ton up and 2.5 ton down. When I told him what he missed, he recalculated to match Raleigh's numbers. They would "only" install a climatemaster 27 downstairs and I wanted a 20 (single stage). Also they were locked in a contract with only one driller, and they have the least experience.

Boman has by far the most experience going back 30 years. Good guys, and I would totally trust them, but they were less detail oriented, did no load calculations, and recommended 3/2.5. When I asked about the load calcs they agreed I could do a 2 ton down. They were also backlogged with work, which explains their lack of details and the quote they gave.

Numbers were something like this:

Raleigh - $18k units, $15k wells
All American - $20k units, $16k wells
Bowman - $22k units, $13.5k wells

The deciding factor -- Raleigh H&A picked Boyette Well to do the wells. I had previously spent 30 minutes on the phone talking with John Boyette Jr and they were my #1 pick. When Boyette came out to talk to me, I asked if they would match Bowman's price, and they did. I also found out that Boyette was one of only a handful of GSHPA certified drillers.

After I told Peter and John that I was a "go" things moved pretty fast. I got the lowest HVAC install quote and the lowest drilling quote. They got me scheduled for drilling last Fri, and install completed today.

Next up: Drilling! Gotta go download some pictures...

Scott Johnson · **Posted:** Sat Oct 16, 2010 8:11 am

Should have asked this before.

If you had natural gas coming to the house, would you have considered this option?

Scott Johnson · **Posted:** Sun Feb 27, 2011 10:59 am

Updates?

MikeWhitney · **Joined:** Wed Aug 20, 2003 9:15 pm **Posts:** 4724

scottjohnson wrote:

Updates?

Sorry never had a chance to finish my story, mainly since it's working perfectly and I love it, it's faded from conscious thought

Added about $80-100 to Dec/Jan electric bill and about $40-50 to Feb.

One neighbor paid $750 for propane for one month, and the other keeps his house at 62-65 to keep the bills down. So we're on target for $2500-$3000 savings. Will be interesting to see how cheap AC is in the summer.

Me, we're at 67 night and 71 day.

Reminds me I need to go check our propane tank (for hot water only) and see how much is left!

BretLuter · **Posted:** Sun Feb 27, 2011 3:40 pm

MikeWhitney wrote:

scottjohnson wrote:

Updates?

Sorry never had a chance to finish my story, mainly since it's working perfectly and I love it, it's faded from conscious thought

Added about $80-100 to Dec/Jan electric bill and about $40-50 to Feb.

One neighbor paid $750 for propane for one month, and the other keeps his house at 62-65 to keep the bills down. So we're on target for $2500-$3000 savings. Will be interesting to see how cheap AC is in the summer.

Me, we're at 67 night and 71 day.

Reminds me I need to go check our propane tank (for hot water only) and see how much is left!

Mike,

sounds like a good savings.

Did you consider using the geothermal system to heat water? I don't know how much $$ it would have added to the install, but the way I understand it, it's essentially free hot water in the warm months (when the AC is on) and cheap when the heat it is on.

Desuperheater (??).....

Brian Marks · **Posted:** Mon Aug 01, 2011 10:13 am

So how's this working out for you guys so far? My power bills have been KILLER the last few months - around $450 per month (GASP). I wonder if this is a good solution for my summer cooling bills. I don't suffer so much in winter, although if it's very cold out, we can see $200-300 for gas bills (LNG), but this electric a/c is really killing it for me.

If geothermal even makes sense, I wonder if they can drill in the front yard (Mike, you've seen my house where the front circle is - do you think a well can be drilled in there?)....I'd like the contact info for the people you had do yours.

Brian Marks · **Posted:** Tue Aug 09, 2011 9:01 pm

Mike?

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