Geothermal heating systems

[MN Gardener]

Does anybody have one? What are the pros and cons? How expensive are they? What kind of warranty do they have? I have heard the outside parts are suppose to last 25 years and the exterior stuff 50+ years but DH has a friend who has had to change out his inside stuff twice in 7 years. We are trying to decide whether it is something we can afford now, or should save up for. We are in almost 100% sandy soil and have a low water table (I thought it was 11 feet, but I guess it is more like 8 feet). I really want the system, but I have only heard the pros but not the cons.

[Razorback21]

We did a retrofit in our house and I will tell you the good and the bad...good, it has lowered our overall energy cost, most of it coming via the elimination of propane. Operates very quietly, and free hot water in the Summer is nice. Now, the bad...we didn't get all the savings that was advertised, especially electricity. Our usage is up about 10% vs. before. Our payback was calculated at 7 years, now we are looking at like 9 years.

We have a high water table, but it reallyhasn't really affected us too much. One thing I was told, don't know if it is true, the colder your ground tempature is, the less efficient the system is. Here in Southern Illinois, our ground temp is 60. Might want to check into that.

[WisJim]

If you need both heating and air conditioning, and have lots of money, it would work for you. For most people in Wisconsin, Minnesota, or other norther states, it makes more sense to improve your house insulation and weather sealing so you use less heat, than to spend a minor fortune on a new heating system. I have talked to quite a few people with geothermal who have been disappointed in the operating costs and the maintenance or replacement of compressors that has been needed.

[MN Gardener]

This would be new construction, so we are going to need a heating system either way, but I am assuming geothermal is going to be a tad more expensive! We will be insulating very well too.

[SueMc]

We are also looking at this system for new construction, but have never had experience before. The man who will be drilling our well(s) has an open system, from well to house to pond, and likes it very much. He said he will be able to tell when he drills our well if we can use the same system. Initial outlay for an open system is much less than a vertical or horizontal system. I work with a woman who had a vertical system installed some years ago and is really pleased. I'll have to ask her how long it was until she broke even.
I'm in Central IL.

You probably already know that there a lot of websites when you google geothermal. There are also some videos on youtube that shows installation and how things work.

[SolarGary]

Originally Posted by MN Gardener

This would be new construction, so we are going to need a heating system either way, but I am assuming geothermal is going to be a tad more expensive! We will be insulating very well too.

Hi,
I would consider putting the extra geothermal heat pump money into a a very good thermal envelope instead. Insulation never wears out

If you want to see how far a good thermal envelope can get you, Google "Passive House Institute US". Homes built to this standard need very little space heating, and can often be heated by a small heater placed in the Energy Recovery Ventilation system -- this avoids the cost of a separate furnace and duct system.

You might also take a scan through the solar homes section on my site:
http://www.builditsolar.com/Projects...solarhomes.htm

The Construction page gives a lot of examples of constructing thermal envelopes that have low heat loss.

Gary

[agmantoo]

I have an open loop system. My well water comes into the home at ~56 F and goes through the geothermal unit that is in the basement and them dumps the water onto the surface of the ground in the woods behind my home. If I were in a colder climate I would dump into the small pond that is further from the house. During warm weather the water is available for my garden or other uses. There are no negatives from my viewpoint. Time after time here on this site the price of the units surface as a negative. There is no justification for the prices charged as the unit is cheaper to build than an air to air heatpump. The units are very small and they are precharged at the factory. There are no components of the geothermal unit mounted outside to rust or fill with debris. You can buy a geothermal heatpump off the internet and they will take you house plans and design the system. If someone is available with basic mechanical experience the unit should be no more difficult to install than an outdoor boiler. When the time arrives for the unit I have to be replaced I plan on doing the change out myself. My utility bill is far less than anyone I know with a comparable size home. I have rental property that is significantly less footage that has electric bills 2 to 3 times greater than mine. The heat out the registers from a geothermal heat pump is hotter than that of an air to air unit and the air conditioning is far superior. To extract cool from cool well water the unit hardly has to work. Over the time I have had the geothermal heat pump the house has remained comfortable to the point that visitors often comment on how they wish their home system worked like mine. I figure that my heating/cooling expense is about 1/3 of what it would have been otherwise. It is amazing what the SEER rating is on the newest geothermal units so the cost of operation should be even less. I have had only one problem over the ~18 years my unit has been in service. I made the repair myself. I consider the units as dependable as a basic fridge and only slightly more complicated.

[MN Gardener]

Originally Posted by SolarGary

Hi,
I would consider putting the extra geothermal heat pump money into a a very good thermal envelope instead. Insulation never wears out

If you want to see how far a good thermal envelope can get you, Google "Passive House Institute US". Homes built to this standard need very little space heating, and can often be heated by a small heater placed in the Energy Recovery Ventilation system -- this avoids the cost of a separate furnace and duct system.

You might also take a scan through the solar homes section on my site:
http://www.builditsolar.com/Projects...solarhomes.htm

The Construction page gives a lot of examples of constructing thermal envelopes that have low heat loss.

Gary

Thanks Gary, I have actually checked out your website on many occassions and will be making sure we are superinsulated, with a good thermal envelope. We will be making good use of passive solar energy (south facing, proper overhangs, good windbreak and many trees north of the house). We are building a 36 x 52 home on a slab with in floor heat. The house would be smaller, but I work from home and need to have a 3rd bedroom for an office. We would like to do ICF for construction, but will not be able to afford that. If we don't do SIPs then we will be doing spray foam insulation. We are set up for off peak electric and are now trying to decide if we should go electric, propane or geothermal for heating. We are just wondering if it is overkill and how long it would take to pay for itself.

Also, is a Energy Recovery Ventilation system the same thing as an air exchanger?

[MN Gardener]

agmantoo....where is the best place to buy the units? DH is pretty mechanically inclined and we have a well driller in the family.

[backachersfarm]

We are thinking of doing this too. My husband is now in the business of working on hvac syst. I don't personally approve of the pump and dump syst, because they waste so much water..even if it goes to a pond. When we do one it will be a closed loop sytem. I have some word that folks with pump and dump have extra stress on their well pump motors, and I think most pump motors require pulling the whole thing out of the well to change it.

[highlands]

We have geothermal by running air through pipes underground to bring fresh air in during the winter. Outdoor air can be deeply sub-zero and the air entering the house will be well above freezing.

http://sugarmtnfarm.com/blog/2008/09...air-tubes.html

[Batt]

Are you actually talking about geothermal? Or are you referring to a "Ground Source heat pump"

Geothermal is the equivalent of tapping into Yellowstone. A ground source heat pump uses the temperature of the ground/well/pond or lake to provide water of a consistent temperature for the heat pump. Unlike a standard heat pump which uses the ambient air temperature.

Makes a major difference.

[MN Gardener]

Originally Posted by Adron

Are you actually talking about geothermal? Or are you referring to a "Ground Source heat pump"

Geothermal is the equivalent of tapping into Yellowstone. A ground source heat pump uses the temperature of the ground/well/pond or lake to provide water of a consistent temperature for the heat pump. Unlike a standard heat pump which uses the ambient air temperature.

Makes a major difference.

I guess ground source heat pump....but most everything I read says geothermal heating systems, so I used those terms. I sure wish I could tap into Yellowstone! My house would be a sauna!

[JUllom]

We installed Geothermal in 2003 in new construction. If building new, it is one of a few things that i would make sure i spent the money on (insulation, doors/windows, etc). We are all electric, 1900 square feet, 7 people, and about $1700 a year in electricity. We use the "pump and dump" system - dump the water into a creek and use for irrigation at the right time of year.

[phrogpharmer]

In this area the local college campus, several churches, businesses, fish farms, greenhouses, and quite a few homes are geothermaly heated with warm water from deep artesian wells. Some of the wells have enough pressure and flow to run hydroelectric generators and then use the water for heating and then aquaculture and then irrigation. It is quite an amazing resource.

[Batt]

Originally Posted by MN Gardener

I guess ground source heat pump....but most everything I read says geothermal heating systems, so I used those terms. I sure wish I could tap into Yellowstone! My house would be a sauna!

When I did an upgrade on my home about 5 years ago we went with a ground source heat pump for our 1600 s/f home. I did quite a bit of the work myself since I had found an installer who would work with me.

Hired a backhoe operator who dug 4 250' long ditches 5 ft deep. Purchased 2000' feet of special hose to put in the bottom of the ditches, and used a bobcat to back fill. At the contractors instructions I added 2-2" pvc pipes through the basement walls (heat pump is in the basement). When I was ready the installer hooked all the piping into manifolds then thru walls to 2 pumps, then to the heat pump.

Outcome: Only maintenance has been to change the filters every month or so. Heating and cooling expense is roughly $1.50 per day in the winter and about $1.00 per day for cooling in the summer. And I like "Meat locker" cool.

I got the heat pump "free" (normally about $4500, that is a story in itself) the rest of the material was about $2500 and labor was around $1400.

DW & I are definately pleased.:baby04:

[agmantoo]

Here is a source that I am considering for a replacement unit
http://ingramswaterandair.com/geothe...79bab3fb9158c4

[agmantoo]

backachersfarm

The pump and dump is not a waste as I see it. The water was sourced from the ground and returned to the ground. The biggest plus is that the open loop system is more efficient even after considering the cost of pumping the water. I too thought that I wanted a loop until I did more research. If you have the area to dump then it is the way to go and is much cheaper.

[Dexter]

I just spent 4 years considering this and finally decided against it. In reality you likely will never pay it off. The salesman are convincing and sware their own homes are practically free of heat/cooling bills. I'd love to see their bill.
It is viable with a huge home. Average homes it is not really worth it at the going rate.
If you go for it get a big warrantee, 10 years if possible.
In the end I chose the air source heat pump (rather than ground source) with back up electric furnace. Air source works great down to freezing then the backfup electric kicks in.
So I also got a high efficiency woodstove so that the furnace wouldn't kick in often.

[SolarGary]

Originally Posted by MN Gardener

Thanks Gary, I have actually checked out your website on many occassions and will be making sure we are superinsulated, with a good thermal envelope. We will be making good use of passive solar energy (south facing, proper overhangs, good windbreak and many trees north of the house). We are building a 36 x 52 home on a slab with in floor heat. The house would be smaller, but I work from home and need to have a 3rd bedroom for an office. We would like to do ICF for construction, but will not be able to afford that. If we don't do SIPs then we will be doing spray foam insulation. We are set up for off peak electric and are now trying to decide if we should go electric, propane or geothermal for heating. We are just wondering if it is overkill and how long it would take to pay for itself.

Also, is a Energy Recovery Ventilation system the same thing as an air exchanger?

Hi,
Sounds good.

The Energy Recovery Ventialtor is an air to air heat exchanger. It pulls new fresh air into the house, and exhausts old warm air from the house. The heat from the old air is transferred tot he new air as they pass through the exchanger. There are also some units that recover both the heat in the air, and also the latent heat in the water vapor in the air.

If you seal your house really well (which is good), the ERV (or something like it) is needed to provide fresh air.
Since the ERV requires ducts and vents throughout the house, the Passive House Institute people have been insulating well enough to get the heat loss down to the point where a small heater can be added in the ERV ducting, and this heats the house -- so, no need for a furnace and duuct system. But, in a cold climate, this takes a very good thermal envelope.

I like the closed cell spray foam insulation in that it really seals up the house for infiltration, and prevents condensation problems since its not permeable to water -- also, very high R value. About the only down side is that the studs go all the way through and act as thermal bridges. If a layer of rigid foam board can be added on the outside, it prevents this bridging.

You might also look at the double stud walls, and the horizontal strapped walls (like the Mooney wall). I think that these when used with cellulose insulation are good, and probably less money than a closed cell foam insulated wall. If a lot of care is taken with the vapor barrier, I think they can be quite good. On the "Construction" page, have a look at the "Gimmie Shelter" link -- I think they have a nice system.

I think that if I were building a house today, I would go for something near the Passive House Institute Standard, and use a simple heating system -- the idea being that if you get the heat demand way down, it does not much matter what you heat with. If you need both heat and AC, the SunSavvy house that I added a description of the other day uses a mini-split air to air heat pump -- this seems like a solution worth looking into for both AC and Heat if the demand is not large.

Gary