Just a data point. I'm in SE michigan also, built a 3100 ft house using geo / hydronic. My manual J came out to about 38-40 k Btus. I have a 3 ton pump and supplement with propane boiler. COP will never run 5.6 I don't care who's equipment you're using. Not in the winter. 77K heating load sounds very high to me. I have 30 big windows in my house. Unless you're in a glass house, I'd look hard at those numbers. I have spray foam walls and cellulose attic insulation. I don't know if you're Edison or Consumers, but you're at about 10-11 cents / kwh. Geo can be expensive in Michigan to run. I'm probably about $1600-2000 per year in heating/cooling costs.

Hope the project goes well.

Posted By 86turbodsl on 20 Apr 2011 03:35 PM
Just a data point. I'm in SE michigan also, built a 3100 ft house using geo / hydronic. My manual J came out to about 38-40 k Btus. I have a 3 ton pump and supplement with propane boiler. COP will never run 5.6 I don't care who's equipment you're using. Not in the winter. 77K heating load sounds very high to me. I have 30 big windows in my house. Unless you're in a glass house, I'd look hard at those numbers. I have spray foam walls and cellulose attic insulation. I don't know if you're Edison or Consumers, but you're at about 10-11 cents / kwh. Geo can be expensive in Michigan to run. I'm probably about $1600-2000 per year in heating/cooling costs.

Hope the project goes well.

Your numbers do not add up. I had a call recently from a neighbor with a similar load (and consumers) she has spent $675ish heting the house so far this winter (which apparently isn't over). DTE would be 25-30% less. Folks in NY spend 2-3 times as much on electricity.
It is cheap to run geo in MI. Heck electric baseboard is cheaper than propane that is ~$2/gal or more.

I'm not sure your work is done yet.
j

Consumers is 11c/kwh in the winter and jumps up to 13-14c/kwh in the summer. Wintertime I run 200-250 dollars a month, summer a bit less. I burned 150 gallons of propane this winter. That was $600. How are my numbers wrong? I have a foam encapsulated envelope, cellulose on top of that, 30 big windows, and kids and a dog that don't know enough to close the doors when they use them. I know what the manual J said, I have a copy of it. It was run by my contractor, we're both mechanical engineers.

Michigan electric rates are middle of the road. Not good, not bad. We got rid of the preferential rates for heat pumps some years ago.

I have relatives in Arkansas with Geo that never spend more than $100/mo on heat or cooling. I know geo is biased to cooling with ground loops.

How would DTE rates differ? MPSC sets the rates for all of michigan, last I heard anyway. It's been 15+ years since I worked for Consumers, so maybe things have changed.

DTE supposedly has a geo rate at $.055/kwh off peak.

If I put your numbers into design software (40MBH heating, guess the cooling around 25k, consumers elec. and are you really paying $4/gal propane!?!?) it tells me a wtw 3 ton should handle 98% of your heating load for <$700/winter and your propane usage should be around $70 making total winter cost ~$750. BTW average COP about 3.26.

Cooling about $160/yr so your total annual heat and cool expense should be ~$910 definately not $1600 to $2000.
That's what doesn't add up.

Now what I don't know is your system design including what temp the radiant is designed at (my example is with 110F water;jumping to 130F raises heat bill by $200), what temp you set the thermostat at (my example was 70 in the winter 72F in the summer), whether you are employing a hot water generator (I did in the model which raised heating nearly $50/yr but took nearly $300 off hot water bill for an electric tank).
I also do not know whether you included hot water in the billing (which would bring the numbers closer) or are attributing too much of your baseline electric use to the geo as it is not metered seperately.

What I do know is that I could heat and cool your house the equipment you described for <$900/yr (less with an electric boiler). I also know that your propane usage should be in the 20 gal range for heating. Further you shouldn't be paying $4/gal for propane (yet).

So why are your numbers so far from mine? If your load calcs are accurate where is all the extra energy going.
I'm not trying to bust your chops, I really think you have left something out of your description, or we could be saving you $1,000/yr in energy expense.

btw, Consumers got rid of the heating discount in '08 DTE did not.
j

fwiw; if your system design is an energy hog, it still beats the ~$2,500/yr you'd spend with $2.50/gal propane or the ~$3,800 you'd spend with $4.00/gal propane.
Joe

I paid almost $4 for propane in 2008.

A current client says he is paying almost $5 this year.

Location location location...

Posted By engineer on 26 Apr 2011 01:07 AM
I paid almost $4 for propane in 2008.

A current client says he is paying almost $5 this year.

Location location location...

This spring in mid MI, about $2.50/gal the wily shopper closer to $2.00.

"DTE supposedly has a geo rate at $.055/kwh off peak."

Yes the electricity is metered by time of use. Estimators around here tend to select an average (between 6.5 and 7.5 cents) to catch peak hour use and fees under a flat rate (more computer model friendly).

Hope we hear back from 86, there's definately something going on there costing lots of $$$.
j