geothermal HVAC anyone?

[DeltaBond]

Estimated cost for replacing my HVAC unit with a geothermal one is $19K.  If we replaced windows, beefed up ALL insulation, might need less and bring it down to $14K.  A new traditional HVAC unit will be less than $7K.

Seems if they're wanting people to overinsulate their homes in order for the geothermal to work better, maybe they aren't really all that great just yet.  I'm sure it will cut down on the monthly bill, and won't need replacing until maybe 20 years, I'm not thinking $19K is worth it.

Anyone have one, or know someone who does?  Also, what region do you live in?

[boarder42]

My parents have it. Had to replace after 20 years. But it works really well. They live in kcmo area. There is no gas where they are so it is definitely cheaper than running electric all winter or buying propane.

[Rufus.T.Firefly]

I don't know a lot about geo-thermal units, but my FIL is an HVAC contractor and has installed the units in the past.

He thinks they are fantastically efficient and has explained the math to me on the savings. It sounds pretty good. This is in the PA area where a lot of people use heating oil.

However, a word of caution. He also explained to me that some contractors have installed geo-thermal units incorrectly and the units are terribly inefficient. He had a few stories about homeowners that got screwed by bad installs.

Do your homework on your contractor. Don't just assume they know what they're doing. Get references, etc.

[ShoulderThingThatGoesUp]

I know three people in the Lehigh Valley with it. Two of them haven't had any problems and love it. One had to have it dig up and redone completely because the installer did a crap job. That also gave them high electricity bills because they were heating with electric resistance.

[DeltaBond]

I know three people in the Lehigh Valley with it. Two of them haven't had any problems and love it. One had to have it dig up and redone completely because the installer did a crap job. That also gave them high electricity bills because they were heating with electric resistance.

Are you saying their bill was higher because they didn't have gas heat?

[ShoulderThingThatGoesUp]

I know three people in the Lehigh Valley with it. Two of them haven't had any problems and love it. One had to have it dig up and redone completely because the installer did a crap job. That also gave them high electricity bills because they were heating with electric resistance.

Are you saying their bill was higher because they didn't have gas heat?

I do know one household that switched from gas heat to geothermal, for what I can best describe as ideological reasons. I think their monthly bills went down but I'm sure their payback time approaches infinity.

The household I was referring to that had high electricity bills had their geothermal heat exchanger fail due to poor installation. They don't have gas in their neighborhood and the geothermal systems come with backup electric resistance heaters. When the heat exchanger fails, the resistance heat is all you get, and that's expensive.

[DeltaBond]

Oh, I see, that makes sense now.  And yes, at the cost of them, for a 1500 sq ft house, it doesn't seem to be such a great move that its worth it for me.  I live in the south, sounds like its more helpful in the colder climates.

[hodedofome]

Pretty sure George Bush has one at his ranch house in Crawford, TX. They ended up not needing solar panels after putting it in, if I remember correctly.

[DeltaBond]

That's interesting, HoldTheDoorForMe, I bet his contractors didn't botch the job.

[rulesofacquisition]

Geo is more efficient in air conditioning because you're not trying to dump heat into 95 degree air outside, but into 55 degree dirt or water (warmer further south). It's not new technology and you can find lots of info online. I had it but sold the house due to divorce way before payback. You can wire things so the electric heat has to be turned on manually, if you're in the south you may never need it except for emergencies (well/equipment failures). Check out the tax credit, 30% if you can take it. Some states/utilities offer rebates as well. That said, I probably won't do it again as I'm not sure of my long term plans (current house may become rental).

[laughing_paddler]

There's not often an easy answer with ground-source-heat-pumps, but if you are in a cooling climate, and you spend a lot on cooling, then GSHP can save you a lot of money on your AC.

In Minnesota (obv. a heating climate) the case wasn't so clear (despite what the geothermal heat pump associations say), so the MN Dept of Commerce had an engineering firm run the numbers for several scenarios (No. MN vs So. MN, new vs. retrofit, fuel sources replaced by GSHPs, etc.). The process, analysis, and conclusions were interesting enough that you may want to see them, even though you're in a cooling climate.

http://www.michaelsenergy.com/PDFs/Minnesota%20GHP.pdf

"The small house existing building with the conventional HVAC system had total annual energy
costs from $2,530 to $3,035, depending on location and utility. The small house existing
building with the GHP HVAC system had higher electrical costs, but had no natural gas costs
associated because no natural gas was used in this case. The total annual energy savings for
the implementation of the GHP HVAC system ranged from $453 to $1,140, or 17% to 40% of
the conventional HVAC system energy costs, depending on location and utility. The addition of
the desuperheater water heating option increased the annual savings by an additional $50 to
$83."

[Rural]

My parents have had a geothermal heat pump for near 50 years now, and the big savings for them in the south is definitely AC. They have a spring on their property so didn't have to put in wells, and that made the payback fast. Even without a spring, though, the savings are remarkable over air heat pumps.


Dad did the install himself, but he also built the house. DIY can be an option, though, if you have time, skills, or both.

[Emg03063]

I know someone who has a system (North Carolina, AC contractor, open loop system).  You should always make sure you have a state of the art thermal envelope before sizing your system-- insulation is way cheaper than digging wells.  Having said that, open loop systems (aka pump & dump) are much less expensive than closed loop, on a capital basis, because you have a lot less well to dig. In a closed loop system the ground loop (the more expensive part to build) should last way longer than the heat pump (50-100 yrs vs 7-20).

[Bob W]

I have a well based pump and dump.   Had to have well anyway.   3000sq ft home,  all electric, 140  a month total utility.  Midwest.   Have a certified HERS rater run your numbers.   In most cases a super efficient air based heat pump pencils out better.  Very tight insulation is always good.  Don't use heat strips until below 10degrees for air based.  Ground source don't need them.  I don't have these and it gets 10 below here.  So you won't need heat strips or to run the very expensive 220 wire.  You can also heat your hot water in the summer with a ground based heat pump and dump.

[DeltaBond]

What is "open loop/pump & dump"?
"thermal envelope"?

[ShoulderThingThatGoesUp]

Open loop/pump and dump - I've seen Bob explain it before this way: pump sucks groundwater out of a well/spring, heat pump takes heat from your house and puts it in the water or the reverse in winter, hot/cold water is then released to flow back into nature. Obviously not going to be acceptable in a highly developed area.

Thermal envelope is just the thermal barrier you have between inside and outside - insulation, basically.

[Bob W]

Open loop/pump and dump - I've seen Bob explain it before this way: pump sucks groundwater out of a well/spring, heat pump takes heat from your house and puts it in the water or the reverse in winter, hot/cold water is then released to flow back into nature. Obviously not going to be acceptable in a highly developed area.

Thermal envelope is just the thermal barrier you have between inside and outside - insulation, basically.

yep,   we have lots of ground water in Missouri.   Can't get rid of it.   When I built 1400 sq ft homes I installed high efficient air based heat pumps and tightly insulated.  Top all electric bills were around $100 in February.   It was pretty cheap thrills. Always suggest a HERS home energy audit.   Many utilities pay part or all for these.

[music lover]

The numbers for geothermal don't come close to working around here. My 1000 sq. ft. house costs $400 a year to heat with natural gas, and the monthly electric bill is $60. When my friend built a house 5 years ago, the quote for geothermal was $15,000 more than a standard high efficiency furnace. Factoring additional mortgage interest costs or lost investment on that $15,000, payback would never happen in his lifetime.

[DeltaBond]

The numbers for geothermal don't come close to working around here. My 1000 sq. ft. house costs $400 a year to heat with natural gas, and the monthly electric bill is $60. When my friend built a house 5 years ago, the quote for geothermal was $15,000 more than a standard high efficiency furnace. Factoring additional mortgage interest costs or lost investment on that $15,000, payback would never happen in his lifetime.

What area do you live in?

[music lover]

The numbers for geothermal don't come close to working around here. My 1000 sq. ft. house costs $400 a year to heat with natural gas, and the monthly electric bill is $60. When my friend built a house 5 years ago, the quote for geothermal was $15,000 more than a standard high efficiency furnace. Factoring additional mortgage interest costs or lost investment on that $15,000, payback would never happen in his lifetime.

What area do you live in?

Winnipeg...in the heart of the Canadian prairies. He was quoted $13,000 for a high efficiency furnace (including AC, ducting, etc.), and $28,000 for geothermal. Based on our low energy costs, payback won't happen.