Geothermal heating
 

I assume this topic is mostly valid for us living in somewhat chillier climate.

Is any of you guys heating your house with geothermal and what is your experience? I just installed a 10kW pump connected to 700 feet well and I'm quite pleased, despite only being used in two rooms so far (floor-heating). Other rooms are still been heated by electric radiators but are drawing much less electricity due to warm air flowing from two that aren't.

If I was building new I would look into it, I love the simplicity of it

I installed geo in a house about 6 yrs ago. I think I undersized the unit . It ran way too often and the compresser was kind of noisy. It heated quite inexpensivly until about 10 deg below freezing then supplemental electric heat cut in ,then cost went up.

One of my best buds is GM for a large heating supplier, not an installer, one of the lines they build are furnaces. His opinion is the best value is an air to air heat-pump and a high efficiency gas furnace.

My open concept house had baseboards, I wanted a ground source HP, but he told me the best option for us was a mini-split heat-pump and a couple of gas fireplaces. I installed the fireplaces myself and did a trade with him for the HP.

If I was to build again I'd look into ground source, but only if it was in-floor heat. I'd still have a few gas fireplaces, I really like them and they work even if the power is out.

Mark: that's basically what I've been told. Floor heat doesn't need hi-temp water or big delta-T, which keeps the efficiency up. Once you go for the radiators, heat pump efficiency goes down. So I plan to install floor heat in all room.

Gas would be nice but the infrastructure doesn't exist, so it's gonna be ground source HP all the way. I investigated air-to-air but it's noisy, doesn't work bellow -10C and it's hard to make work for closed rooms.

John: OK, thanks for the heads up. I have the heater unit installed but disabled in software. I have a 100L buffer-tank and right now (-7 deg C outside) HP runs once every 2 hours for like 15 minutes.

I will ask my son-in-law. He put in a geo system to augment forced air propane heating. :rolleyes:

Ian

Installed geotherm. 10 years ago with new construction. Horizontal loop in wet clay. Supplement with a gas fireplace when it gets below 0F. Cool for very little in summer too! At one time I read that geotherm. is up to 400% efficient. I'm not an engineer so that sounds impossible to me.

I installed my collector in horizontal loops about 6 ft deep .about 1200 ft of 3/4 pex.circulating antifreeze connected to a heat pump. It was a water to air type HP and it would have been more satisfactory if I used water to water with infloor heat. I suplemented with an airtight wood burning insert in one of my fireplaces. Rural property with no gas available.

From my son-in-law:

"The geothermal works well. The payback is not quite as good as we were told. We kept our existing forced air propane furnace and put a coil in the plenum. The Dc fan blows past the geothermal coil to heat the house. The heat is not a hot heat it actualy feels cool coming out of the vent but it is adding BTU's to the home and therefor raising the temp. The propane is set as a backup if the geothermal can't keep up. To my knowledge the propane has never turned on since.

The part of the geothermal that the suppliers shy away from telling you is the system uses a compressor. Compressors draw power. 15Amps at 240V and it runs 50 percent of a day. 5 minutes on 5 minutes off. So the hydro costs are high. But the Propane cost goes to zero. It also has a neat feature that they run a line around the compressor to remove heat from it when the compressor is running. This heats our domestic water.

Our system has 4 200' loops buried 12' below ground. It's considered a 4 ton unit. The geothermal also works for AC it just reverses the system. It works like a refrigerator to remove heat from the home.

People think a refrigerator adds cold. It doesn't it removes heat.

I would say we save approx. $350 - $400 per month in peak seasons.

But it was a $22000 investment. If it wasn't for the government grants I wouldn't have done it."

Ian

I designed and installed my own system for about $8500 in 2005 before the big govt grants (the average price is now 20k with a grant covering about 1/2. Funny how that works.
My HP was 4 1/2 ton . The problem I wasn,t completely aware of was the output is rated at an incoming ground water temp of 4 deg C. and falls about 20% at 0 deg C.
My system ran about 5 min on 20 off in the beginning of the heating season but was running almost constantly by the end of the season as ground temps fell.
A larger HP would have run less . The collecting bed was oversized for a 4 ton and could have supported up to 6T.

The only exception to this of which I am aware are the old style cast iron radiators. They will work quite well with a heat pump.

Of course the old cast iron units take a lot of space. I too would do in-floor if I was doing it all over again.

Best
Les

Besides inexpensive heating, keeping the heat inside is essential.
Try boiling water with a thin metal lid, then compare to a wider heavy glass lid.

We installed it a few years ago to replace the original oil furnace in our house. It is still forced air and we had to have some of the ductwork upgraded as the house has an addition on it that added 50% more square footage but they never resized the ducts down the long all. The sir blows 95* out of the registers so it isn't as hot as a cumbustion type furnace, but our house has never been as cold as with the old oil burner. Our bedroom is in the new addition and has/had supplimental baseboard electrical heat and with the oil burner it was still cold. It cost close to $28k because of the ductwork and horisontal boring, but the 10 year mortgage and electric bill increase were far less than the monthly oil charge. Plus it keeps our hot water at 131* when it runs. We never knew the heating element went out of the water heater until spring hit and we didn't use the HP. I don't remember the electric element turning on since the unit was completely hooked up. Don't mess with the thermostat. Just set it and leave it. Summers are great, no noise outside and the compressor isn't that noisy inside.

Had I the choice to do it all over again, I would have done it sooner.

Paul, we were told we get 4 times the heat per kilowat compared to electricity, that may be where the 400% efficient came from.

The estimates we received were less than $900 per year in increased electricity for heating and cooling. We are probably a little higher, but we keep it warmer than the oil burner and cooler than the old A/C unit.

Have you guys run a cost comparison between natural gas or propane vs the geothermal (+electrical, etc)?

What are the total installed cost?
Operating cos per yr on average?

Eg. We installed a 92% eff propane furnace in our 850 sf guest house for about $4000, complete. Propane will probably cost 500-700/yr. electrical for the blower, maybe $100/yr.

Moto, our operating costs are about the same for over 2400 sq/ft. Our installation costs would have been significantly less if we had been doing it for new construction. We have 1-1/3 acre and no where where we could trench enough for the loop between trees and the septic system so it was horizontal bored under all of it.

The way they explained it to me is that it's not the radiator vs floor that is the issue, but the fact that radiator usually needs higher water temps in order to heat up the room (as it's surface area is rather small compared to the floor).

Higher temp in secondary loop = lower HP efficiency.

So it shouldn't matter whether radiator is made of iron or not, as long as it needs higher temp. Also, mixing floor heat with radiators on HP system usually involves a shunt and extra flow pump, which introduce additional losses.

Regards,

I did it with my house in 2002. I have two 3 ton units with about 4000 feet of tubing in the ground on each side of the house. They do work but not a great as we were led to believe. I have added another 2 ton unit and use it just for the master bedroom and master bath. Its works great. Don't max out your system.
I was able to get three 2 ton systems (florida heat pumps, geothermal) at a really good price. I am looking to put these in my shop. I plan on running the geothermal lines down to the lake. Shop is 40 x 60 x 16, insulated, metal. I am hoping 6 tons is enough.
If you put one in, don't forget about you maintenance. When the antifreeze in the lines gets tired, ph drops, and the rust inhibitors wear out, it will absolutely rust out your pump housing. Pumps are expensive.

No sulfur smell?
I think that you have to have a system the re-injects the condensated steam back down where it came from originally or you will have some issues in the future. Just saying...

Thanks for the heads up!

I'm slightly miffed regarding antifreeze in the lines. Which circuit are we talking about? Only circuit containing "antifreeze" in my case is the one that goes into 700ft drilled well. around 300L of it. It's not glycol but 50% ethanol, as leaked glycol would poison the underground water. The hot loop under floors only circulates tap water. The plumber made a nice system which allows me to easily flush/refill the floor circuit with tap water, by opening a valve(s).

This is my pump:
http://www.ivt.se/pages/product.asp?lngID=344&lngLangID=1

Theoretical COP is 4.8, which means that I could get 4.8kW of heat for every kW of electrical power that goes into the pump. But I assume it's only in the best of cases. Brine water goes down to well around 2.6 deg. C and comes back at 4.6 deg. C when pump is operating fully.



Regards,

In Oregon we have geo power very, very close to the surface. Like GEYSER close... In Klamath Falls, there are intersections that are geothermally heated. I lived in a geo heated house for a couple of years - had to open the windows because it was too hot.

I inspected trucks at a shop that had geo heated floors in eastern oregon. It was probably 5 or 6 degrees outside, and the shop floor was too warm to lay on comfortably. Just right on a creeper though. :D

Don't have anything intelligent to add to the thread - just that geo heat in a volcanically active area is amazing!!! VERY hot!

angela