Geothermal related to cooling in Michigan.

[homedad]

I'm at the planning stage of a summer/ retirement home in mid Michigan. My basic question is: Is using a ground source heat pump significantly more economical than a traditional central ac that just uses the outside to dump the heat? My current home electric bill is closing in on $400 per month in the cooling season. During the heating season my electric bill is around $160 and my natural gas is about $125. I love cold and hate sweating as you can see. Does anyone with real experience know if a geothermal system for cooling would offer a drastically better energy bill. The new property has a slightly higher electrical cost per KWH but less than 1 cent. I supplement heating with wood and am not really concerned about heat. Also considering the climate trend I believe that cooling is a bigger factor for me to consider. Thanks.

 

[ponytug]

The short answer is yes, geothermal is slightly more efficient, and should have slightly lower bills for central Michigan.

The longer answer geothermal will not lower your bill by much, and may not lower the cost at all in your lifetime.
Two factors are at play;
1) geothermal systems cost much more to install, either because of the wells, or the trenches to install pipes. They work best when the groundwater level is close to the surface and the pipes can be set in wet soil from the service. They also have to pump water around the loops, or up and down the wells for a standing water friction loss.
2) Air cooled heat pumps used not to function well in extreme cold, but that is no longer the case. Advances in heat pump design have enabled air cooled heat pumps that function in very cold -5F to -20F.

However, for both types, you will be best served by designing a home with super insulation. E.g. 12-16" walls, with offset studs or densified fiberglass outside of the studs, triple pane windows, air heat exchanger, R60 in the attic, double door entryways, and skipping the Viking gas range with its monster exhaust fan.

There are a number of good threads here on heat pumps.

All the best,

Peter

 

[buckeyefarmer]

only if you can do pump and dump geothermal and not use loops, or you have a nice big lake to bury the loops in. Todays heat pumps getting much more efficient. I have 2 geo systems in my house. it has saved me because I installed it myself, and I was burning oil for heat before.

 

[Sawyer Rob]

Move to the U P and you won't have to worry about AC.

SR

 

[hube2]

In the short term it will save you money. In the long term you will never see a return on your investment if you replace what is already there.

 

[ljgordon]

Move to the U P and you won't have to worry about AC.

SR

Thats BS. I've worked up there in 100 degree weather. However, I love it there and most of the time it is nice.

 

[Sawyer Rob]

I didn't say it didn't get hot there, but it's the exception not the rule.

It get's hot in Alaska too, but no one has AC in their house.

SR

 

[KennyG]

Not sure where you are living now and exactly where you are moving, but the cost to install geothermal is high and Michigan doesn't exactly have a high A/C need. I'm fortunate to live near the lake so we don't have a lot of extreme heat. I only run my A/C a few weeks a year when the humidity gets high.

I would suggest checking with some people in the area as to how much A/C is really needed. Even using geothermal for heat it's hard to make the high installation cost make sense in my area and it never would for A/C.

 

[tractortroof]

Big payoff for heating. AC use up there? No way.

 

[CH4Ohio]

Kinda surprised by the responses so far. I would expect operating costs would by MUCH lower with geothermal. You're using a fairly constant ground temperature as your heat sink which should help a LOT with the cold up there. AC is much more efficient than ambient air exchange. Plus you get essentially free hot water when the AC is operating. In your situation, I'd install horizontal ground loops and not look back.

 

[CH4Ohio]

Also, take advantage of the tax credits for installation. Lower electric use will only get more valuable as these "green" initiatives continue to hike electric rates.

 

[dodge man]

Yes it might pay for itself. I’ll tell You what we did. Our AC was shot so we were going to have to spend the money anyway and our furnace was fairly high efficiency but broke down about every other year. We put geothermal in 9 years ago.

Some things in our favor. With the large tax credits at the time we put in a $20,000 system for $13,000. We wrote roughly $7k directly off our tax bill. We also had a large enough yard they ran the loops horizontally. They directional bored it in a did all those loops on a day. We also heated with propane which can be all over the place for price. At that time the payback was less than 5 years. He broke down the savings and it seems like the AC side of it saved us more than the heat side. Ours had been flawless until this year. It still worked but kept locking up and would require a reset. It needed two new electrical boards. Cost to fix was $89. It was still under warranty but that expires in a year.

Until about a year ago we were paying about two cents less a kilowatt hour for the geo. The electric company did away with that about a year ago. We also put in two new water heaters, one is electric, the other gets “free” hot water from the geo. When it’s really cold out and the geo runs a lot it supplies a lot of the hot water. When it’s not running much, very little free hot water.

My opinion would be if you need a new furnace or will need a new one soon, the tax credits are still there, it’s worth getting a quote. We got a comparison at the time we put ours in and geo was clearly the winner at that time. For a 1900 sq ft house with a full basement, our electric bill runs about $250 a month on average. We also like it cool during the summer, especially at night.

 

[CH4Ohio]

The free hot water during the summer is a benefit that you don't want to overlook. As your water-source heatpump extracts heat from your house to cool it, a desuperheater unit transfers that heat into a hot water storage tank and heats your water (or supplements your water heater's operation).

You mentioned the "climate trend" as a concern. Personally, I'm not convinced that we're in a noticeable temp increase trend, but there's no doubt that all the solar and wind that's being added to the grid is causing our rates to go UP much faster than they would otherwise. That's the "trend" that I think GEO best addresses -- lower utility costs.

 

[KennyG]

I need to replace my furnace at some point, so I looked into geothermal or heat pumps. It just doesn't make sense. I burn some wood in a wood stove but mostly heat with natural gas. My house is pretty large but when I look at a gas bills for a year and subtract the cost of gas for hot water and the grill in the summer months, I come out with less than $600 a year. How long would it take to save enough to pay for geothermal? Maybe 50 or 75 years.

I use A/C so little that my highest electric bills are in the winter for the hot tub and keeping my wife's plant room up to temperature.

I'm sure it's a good choice for some people but sit down and do the math before you spend the money.

 

[CH4Ohio]

I need to replace my furnace at some point, so I looked into geothermal or heat pumps. It just doesn't make sense. I burn some wood in a wood stove but mostly heat with natural gas. My house is pretty large but when I look at a gas bills for a year and subtract the cost of gas for hot water and the grill in the summer months, I come out with less than $600 a year. How long would it take to save enough to pay for geothermal? Maybe 50 or 75 years.

I use A/C so little that my highest electric bills are in the winter for the hot tub and keeping my wife's plant room up to temperature.

I'm sure it's a good choice for some people but sit down and do the math before you spend the money.

Good point! Have to consider the options where you're at. There's no natural gas where I'm at so using less propane and avoiding the seasonal cost fluctuations would be huge.

On the other hand, the OP seems to be mainly concerned with AC summer use. It's hard to say how much more a properly sized system would cost over a standard AC condenser/furnace combination. I also think that the 30% tax credit for installation of a geothermal system is still in place so that's a big factor on a new build proposal.

 

[dodge man]

Natural gas can be hard to beat. A lot of any savings you get depends on what you’re using now for heat. At one point we paid over $5 per gallon for LP.

The people that put our geothermal in didn’t just install geo, they did gas, LP, heat pumps etc. They weren’t going to care one way or another so I trusted their breakdown of what was best for us. Any honest HVAC company can run the numbers for you.

 

[ponytug]

If it were me, I would run my own numbers...not so much a question of honesty, just I want to understand the assumptions, including what ROI on the money is, the expected payback time, and the cost of capital, e.g. If it gets financed at, say, 7%, does it pencil out? The OP, @homedad, already lives in the general area, and can get local quotes for geothermal heat pump, an air source heat pump, and propane/natural gas with AC, and see what pencils out for him.

Here the labor costs for the geothermal pipe install just make the payback period longer than the expected lifetime of piping, much less the heat pump itself, but it is always worth checking, as I know in other areas it is not anywhere near as expensive.

All the best,

Peter

 

[tractortroof]

I have been an AC contractor for 20 years.

The original question was:

Is there a significant savings with geothermal in AC (in Michigan) over Air to air (conventional ac)

Even in north Florida with 2000 hours of use per year, the AC only savings is not very significant.

Geothermal savings shines bright when used for heat, especially in a northern climate.

But the OP didn’t ask that.

The limited use for AC isn’t even close to being a good investment.

 

[fishheadbob]

Geothermal saved me a bundle, paid for itself in under 5 years; my savings came from the heat side of the ledger. The OP is saying mid Michigan. I would speculate that Western New York and Mid-Michigan have similar climates. The air conditioning and hot water are wonderful side benefits to my geothermal but would never come close to breaking even if used mostly for air conditioning. An earlier poster said to insulate heavily instead; I would say the same.

 

[homedad]

Move to the U P and you won't have to worry about AC.

SR

I'd have to go alone because my wife would never move that far from her family although she loves vacationing there.