GeoThermal vs Heat Pump

Lore · Posted: Thu Jul 24, 2008 7:54 pm Post subject: GeoThermal vs Heat Pump

In my new "Fortress America", here in the the woods of western Michigan, I'm finishing off the new place. I've been in a bit of a whirl, trying to figure out the best heating system to put in the house The GeoThermal prices are coming in at around $30,000 for a closed loop system. I've considered this as an alternative to a high efficiency propane gas boiler system with an external wood fired boiler backup. It would be cheaper to go with "pump and dump" for GeoThermal, but the water here in MI is full of rust and calcium. My problem as well with GeoThermal is that I have radiant floor heating in both my lower level walk out and garage/workshop, which is already installed in concrete, with not enough of the PEX tubing for heating it with such a system. So the GeoThermal would not work as affectively as it should.

My heating guy suggested why not try a heat pump, an addition of only $1,500 more plus the boiler backup. They are putting in a few and consider the savings to be a 1/3 off the expences of the propane boiler alone for heating in a season. The Heat Pump would work well to about 20 degrees and then the boiler would take over. Plus, I would still qualify for a 40% reduction from the power company for putting in this type of system.

Does anyone have experience with Heat Pumps?
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Cashmere · Light Sweet Crude Joined: Mar 27, 2008 Posts: 1484

Heat pump works till 20?

That would be a newer feature.

Back when we were on HP in a small apartment, it worked until about 40 - below that it wouldn't warm the place past about 60.

Then the giant hair dryers would come on and you could hear the electric bill piling up.

I don't know how much of a DIY type of guy you are, but I've seen systems for 5 grand (no ductwork) that you install yourself.

You could rent a backhoe or find a friend with one, and lay the lines in in a day.

Maybe even a ditch witch would work, if it went deep enough.

The inside system looked simple.

30 grand? Man that seems steep.

Good luck.
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frankthetank · Posted: Thu Jul 24, 2008 9:40 pm Post subject: Re: GeoThermal vs Heat Pump

My brother was telling me his friend that has a geothermal system (the one with the tubes in the front yard full of antifreeze stuff) is not saving him much. It was put in less then 2 years ago (brand new home). This is in southwest Wi, where temps last winter hit -20F+ and went below 0F many, many times.

Heres the kicker, his buddy said that he can turn the whole system off and just use gas. When he did that one month (because it was too cold????for the geothermal pump) he only spent $30 more on his heating bill...meaning he's saving VERY little on his investment...

I told him something has to be wrong...

The guy paid around $25K for the system.
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mos6507 · Posted: Thu Jul 24, 2008 11:50 pm Post subject: Re: GeoThermal vs Heat Pump

Starvid · Posted: Fri Jul 25, 2008 2:06 am Post subject: Re: GeoThermal vs Heat Pump

Are you talking about a groundcoupled heat pump, or one put in a lake, or one taking energy out of the air?

The latter is much cheaper but stops working when it gets too cold outside, while the two previous work even if temperatures fall to -20 C, but they require much more capital, mainly because of the cost of drilling the well.

Heat pumps of different kinds are used extensively in Sweden and would be considered a rather mature technology over here. Heat factors are usually about 5 (that is you get 5 kWh of heat for every kWh of electricity inserted into the pump) as long as the medium you take heat from is warm enough. Another good thing is that can run it backwards in summer so you don't need air conditioning, even if that shouldn't be needed in the first place in Michigan.

It's important to know how much heat you have in the ground/lake. If you overestimate it the well will produce too little heat and if you underestimate it you will make the well deeper and more expensive than needed.

An interesting way to change the capital cost requirement is to drill a more shallow well but adding a solar heating system. This means that solar collectors are installed on your roof and recharges the well with energy during summer which means there is more energy to take out of it in winter. The well becomes cheaper to drill but you get the added cost of installing the solar system. It's the one solar technology that can actually make economic sense.

If you get a heat pump (and I generally think they are a good idea), make sure you use a big well-known company and can get a refund/free repairs if the system breaks down within 5-10 years, especially if you don't take the cheaper aircoupled heat pump. These things have a tendency to break or not to deliver the expected capacity if they are done sloppily.

One of these quality companies is NIBE. They don't sell their products in the US, but they do sell them in the UK. I'm sure you can mail them and ask them what companies in the US make quality equipment. They should know.

http://www.nibe.co.uk/
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IslandCrow · Posted: Fri Jul 25, 2008 2:34 am Post subject: Re: GeoThermal vs Heat Pump

I went the ground heat exchange route rather than air heat exchange. The capital costs were much much higher, but it was more efficient (and as Starvid wrote works at colder temperatures).

Doing some spreadsheets on likely costs it was a toss up (depending on just how fast energy costs will rise), but at time stage I put it in, I had enough cash for ground system so I went for that. This was in part to reduce future costs as much as possible given uncertain economic conditions (and retirement coming up in the not to distant future).

The heat pump has worked well - we have a south facing outcrop of granite into which the well was drilled, so it stores plenty of heat in summer. Last winter the axillary heating coils only came on for a couple of hours all winter! On very cold days we plan to use the wood stove in the kitchen as extra heat.

[To make Starvid happy: the equipment came from Sweden Smile

]
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skyemoor · Posted: Fri Jul 25, 2008 4:19 am Post subject: Re: GeoThermal vs Heat Pump

Tell us about your square footage (and if you will be heating the garage most of the time). What is your wall insulation (R-21? R-25? other?), ceiling insulation?

All things being equal, the geothermal heat pump will cost about 1/4 to 1/3 the electricity of an air source heat pump. Since you have a fossil fuel backup, it may be closer to 1/3 to 1/2, though then you have to add in fuel costs.

If you are in the woods, I'd say put in an efficient woodstove and use that primarily (or at least when the temps are below freezing). Then a $30k geothermal system wouldn't be necessary.
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Kingcoal · Posted: Fri Jul 25, 2008 6:03 am Post subject: Re: GeoThermal vs Heat Pump

A friend of mine has a "pump and dump" and is very happy with it. However, you have to keep after the heat exchanger, cleaning it regularly of mineral deposits. We also have hard water here.

They give you almost free air conditioning in the summer and work well in the winter even with sub zero temps because the well water stays at a constant 45 degrees year round. He's gone through some pretty cold winters and has never had the exchanger freeze up.
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purdum · Tar Sands Joined: Feb 15, 2005 Posts: 31 Location: MI, USA

Lore - I'm also in Michigan, near Lansing. We installed a ground-loop geothermal system in 2005 and have been very happy with it, saving a lot of money each year compared to the oil furnace we had before. Our basic costs were $11K for the heat pump and $7K for excavating and installing the loops. The total cost was closer to $25K because we had to install a separate 70-amp electrical panel and ended up replacing just about all the ductwork in the basement. With heating oil likely to be around $4.75/gal, we will save nearly $3500 just this coming season. And it has been costing us about $125 for the entire summer for air conditioning. So yes, $25K is a lot of money up front but it will pay for itself by 2012. PM me if you want more details.

Lore · Posted: Fri Jul 25, 2008 8:39 pm Post subject: Re: GeoThermal vs Heat Pump