Geothermal related to cooling in Michigan.

[homedad]

Thanks for all of the opinions. With my limited knowledge of geothermal I assumed that the 55 degree ground temperature would have been a huge advantage but I never considered the need for a compressor. It's a lot of empty land and I'm capable of installing trench loops but the electricity is the deal breaker. I only use AC for sleeping so I suppose I'm better off sleeping in a small guestroom with a window unit.

 

[hube2]

I only use AC for sleeping so I suppose I'm better off sleeping in a small guestroom with a window unit.

I installed air sourced heat pump for the reason of the eliminating the noise from window units. Air sourced will not be as efficient as ground but will cost a whole lot less. I did not install them to save money on AC.

I am however spending significantly less overall when I factor in heating costs. Still, it will take me nearly 20 years (if I live that long) to get my money out of them. But air sourced pumps only have a life expectancy of 10 to 15 years which basically means that I will never see a return on investment unless the cost of fuel oil triples or more in price. And I still need the oil fired furnace for the really cold days below the range of the pumps.

But it did not matter, I could not take the noise from the window units any longer. The heat pump is silent, you don't even know it's running.

 

[dodge man]

Think of geothermal like a regular ac unit but you go outside and spray the hot coils with water. It’s a little more complicated than that but that’s the general idea. Mine uses a little less than 2000 watts when it’s running normally on stage 1.

 

[KennyG]

If you only need the heat or A/C in limited areas and want to minimize the noise, look into mini-splits. They are not that expensive, you can do your own install and they are efficient. The A/C will be very efficient in Michigan if you can install the outside unit in a shaded area.

 

[deezler]

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

Lol ok bud. Much of the UP hasn't been over 100 degrees in decades. Here's data from Marquette, for example. Most years top out in the low 90s, and even those kind of heat waves typically only last a few days at most. Plenty of summer days that don't even hit 75. Depends on proximity to the lake shores, I suppose.

Highest Temperatures in Marquette by Year

www.extremeweatherwatch.com

 

[deezler]

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.

Peter

Dang, Peter nailed it on the first response! Should have closed the thread right after this post.

I would say that yes, geo-thermal will still be more efficient in mid michigan (especially with wet soils as others have noted) BUT, the install expense will take a lifetime to pay back.

Even with a gradually warming climate, mid-michigan has few days where A/C is truly warranted (10-15 max). Design your home with the climate in mind, and you barely need it (roof overhangs to prevent sunlight entering in summer, thick insulation everywhere, earth-berm the north wall of your house, etc). Overnight humidity in mid-michigan is rarely bad enough to prevent you from using free a/c all night long, then close the house up in the morning and you can hold in the 70s all day. But the beauty of starting with a well-designed and efficient home in the first place, is that one little mini-split heat pump system ($2500 DIY install) can easily hold you in the mid 70s with minimal electricity consumption. In our house in Southern Michigan it takes a few days of heat wave before we need to turn ours on, and then we don't feel guilty about setting it to 74°F cooling, because it sips electricity given the house design. Maybe 50 cents/day.

But the best part about mid-michigan is that usually the weather/air arriving to your location has passed over a great-lake and gotten free air-conditioning on the way! (which is also why its pretty cloudy all winter long).

 

[ponytug]

Dang, Peter nailed it on the first response! Should have closed the thread right after this post.

I would say that yes, geo-thermal will still be more efficient in mid michigan (especially with wet soils as others have noted) BUT, the install expense will take a lifetime to pay back.

Even with a gradually warming climate, mid-michigan has few days where A/C is truly warranted (10-15 max). Design your home with the climate in mind, and you barely need it (roof overhangs to prevent sunlight entering in summer, thick insulation everywhere, earth-berm the north wall of your house, etc). Overnight humidity in mid-michigan is rarely bad enough to prevent you from using free a/c all night long, then close the house up in the morning and you can hold in the 70s all day. But the beauty of starting with a well-designed and efficient home in the first place, is that one little mini-split heat pump system ($2500 DIY install) can easily hold you in the mid 70s with minimal electricity consumption. In our house in Southern Michigan it takes a few days of heat wave before we need to turn ours on, and then we don't feel guilty about setting it to 74°F cooling, because it sips electricity given the house design. Maybe 50 cents/day.

But the best part about mid-michigan is that usually the weather/air arriving to your location has passed over a great-lake and gotten free air-conditioning on the way! (which is also why its pretty cloudy all winter long).

Thanks for the compliment!

It sounds like you have a really well designed home. Perhaps there ought to be another thread on efficient and well designed homes in particular.

The climate in mid Michigan is pretty sweet, although I admit that I find those winters pretty grey.

On the bright side, there's a bunch of great people there, too!

All the best,

Peter

 

[not2old]

Just to give you an idea on the efficiency of geothermal, my blower motor quit a couple of weeks ago and I had to heat the house with electric space heaters. I calculated the electricity usage to be about $40.00 per day for a week and that would have cost me about $1200.00 had I needed it that long. My usual electricity bill for a month this time of year is about $300.00 for everything electrical we use. New motor was over $1600.00 with freight from Texas, plus labour.

 

[mikester]

Like others have said a GSHP will cut your cooling costs by about half.

The real question is WHY you are spending $400/month on cooling costs. Do you leave all the windows and doors open and the A/C on full?

Here's an interesting quote for you "80% of a building's cost in it's lifetime is the day to day operation, NOT the construction cost".

Check out Passiv Haus

 

[Sigarms]

If you only need the heat or A/C in limited areas and want to minimize the noise, look into mini-splits. They are not that expensive, you can do your own install and they are efficient. The A/C will be very efficient in Michigan if you can install the outside unit in a shaded area.

With mini splits (ductless which everyone thinks about or ducted), generally the cost is associated with the actual performance for capacity available for both cooling AND heating.

I can buy a 1.5k mini split or 3k mini split from the same manufacturer at the exact same capacity size. Reason for the price difference? Generally the amount of heat that system can provide in colder climates.

I've dabbled with Geo (perhaps 10 jobs) in NC and that's it. It is expensive, but if you can provide your own labor for the digging and piping, it's something I would look at because Geo equipment isn't that much more than "higher end" HVAC equipment.

That said, generally what people forget about is the ductwork. Sheet metal, insulation and general duct layout (manual D) attributes a good percentage of the overal price as well.

With ductless mini splits, no duct is needed which is great (saves time and money of course). That said, I'm a big propronent of ductless mini splits for single up to 3 zone applications, but for using it for the whole home (where depending on the layout, more than 3 zones are needed), I'm not a big proponent due to potential future service issues as well as swing in temperature zones within the house given it's location and layout.

If the OP will be using wood for back up heat, I'd give serious consideration of the layout of the home to maximize that fuel source.