So I am in the design process of a 5260 square foot house, the plan is polished concrete floors, concrete walls, concrete second floor slab, concrete flat roof, proably quad lock system. The house is 2760 sqft, and the garage shares a wall on the north side and is 2500 sqft. A few things i want for sure, in floor heat, I want a wood stove down stairs, and a wood stove up stairs, the garage is getting infloor heat, but also a oil burner, it's a mechanic shop and I have a endless supply of clean oil. Now these are all supplemental heat sources, I'm wondering what should be my main heat source, the quite constant reliable one. I have access to natural gas, propane, electric, water well, but there is no sun or solar potential, I'm buried in trees. My original plan was to keep the house all electric, and not run gas or water line, and only have one bill, electric. I was thinking geothermal and use cistern as a heat exchanger, I've seen that idea shot down about a dozen times on here, I had alot of variables to throw into that idea, but instead of driving you guys crazy with convoluted heating schemes, I'll take suggestions on a heating and cooling source. The garage is also cooled by swamp coolers, so heating is really the main concern. My architect calculated 200k BTU, seems high to me but I'm not the one with the software.

Subscribing. I want to build a heated driveway so I will be interested in your progress and the heat exchanger option.

Not to burst your bubble but many of us had the same thoughts as you. Couple notes from doing it wrong myself. Heated floors in garages are the biggest waste of money. They take like 8 hours to heat up and unless you want to constantly waste money and leave them on, it is not worth it. I was a mechanic also have to have is warm to work here in Michigan. Garage doors waste so much heat so heating as needed is the only option in my mind.

I have built 2 houses and done lots of heated floors in them. Our current house has heated floors throughout and geo and naturel gas and solar. I heated the house last winter with wood and spent $600 on wood and only saved $350 on or heating bill. We only use wood for enjoyment now.

I have ran the house on geo and natural gas(NG) and NG is over 20% cheaper to heat with then geo. I really don't trust Geo salesmen. I have had 2 houses with geo and both were cheaper to heat with NG. I don't think they calculate all the pumping energy and ducting losses in the Geo cost savings data. Mini spits are calculated out to be more efficient then natural gas now.....

Our house is a large ranch with a 50% exposed walkout basement area. So there is lots to heat in the basement. After 2 years of playing I just completely turned off the circulation pumps in the basement. Our heated floors are pex in a inch and a half of concrete on the main floor. Once the wood flooring was installed the slab now has about the same resistance for the flow of heat going up as going down. So the upstairs floors does all the heating and if the basement floor run at all it instantly gets over heated down there.

For cooling we have the geo but have found that 90% of the time we can just run a sprinkler and have the 50 degree well water run through the heated floors first and cool the house. Now my thermostat for cooling stage one opens a valve and turns on a single tractor(self propelled sprinkler) sprinkler to water the yard. Stage 2 turns on the geo. Stage 2 came on for like 15 days last year. Next time I would get more elaborate with the well water and not do geo at all. Maybe one mini split for main area cooling.

Also note that the more efficient a house is the less heat needed and the floors aren't going to feel warm they are more like room temp until it gets really cold out.

Good luck.

So I'm surprised for a mechanic to say that heated floors arw kind of a waste, so I am moving my mechanic shop to the house, so i will be working out of this garage atleast 8 hours a day, right. Ow I spend more time in my garage then anywhere else in life combined, the cold concrete seems to really wear me down. Also the plan of ruinning the 50 degree well water through the slab is also what I'd like to do, expect it will run through the ceilings not the floors, ceilings are also concrete. I think I can also heat with my well water as well and use the ground water as a heat sink and only drill o e well, 2 wells max, but I have seen that argued against many times in this forum. But if I'm not gonna heat that way i do t wanna drill a well just for cooling. Natural gas is such a obvious cheap and easy choice, I live in one of the largest natural gas producing areas, but I am worried about future supply demand and prices, if I can figure out how to heat without gas then the only bill I'd have is electric, no combustion is the house, no flame. No running a gas line to the property, lots of benefits. But gas is easy and works pretty much flawlessly. So it's kind of crazy to even consider other options, but I'd like to have something differnt as well.

Sounds like a great project. I do question heating a building 24/7 when it is only used 8 hours for 5 days = 40 hours....compare to 168 hours for 24/7.

I have built 2 house with large attached garages. My first was 60x40 attached to a house along the 40 foot length. It had a single large door at the far end, I had a car wash area at the far end and for never being heated more then a couple times a year the water and pipes never froze in Michigan. The problem with this was that it was one big room and everything was out in the open to be seen. There was always crap in view.....I hated it.

Our latest house is a double stack garage. So the upper is 30x40 and lower is 30x40.... The ideas is to keep all the crap in the lower and keep the upper nice...still trying to get to that after moving in. So the upper garage has 2 doors and the lower garage has 1 door. These garages have R30 walls and R60 cathedral ceilings. These garages stay about the same temp as the old house. I have bought a mini split to heat them. They have remotes that can turn them on before use.

The garage floor between the 2 garage levels was $12,000 and then you had to skim coat a cement floor. I really think this was cheaper then the big all one level garage if your property allows it. You have half the roof area to finish, no ceiling drywall in the lower garage ceiling and less concrete in the floors with the prestressed concrete floors.

So I sat down with my engineer tonight and he put my mind back at ease, I'm gonna stick with one water well, fill a large cistern with ground and use that cistern for a thermal battery.flr.the geothermal heat pump. We have talked about it before but went over it again. Tonight and it's the best scenario for me.

Cool keep us up-to-date....how big of cistern is it going to be? 1000 gallons? Does your area have a high water table to help dissipate the heat from the cistern tank?

Remember that the builder is going to make say 5%.....and if you spend $10,000 on a NG heating system he makes $500, but if you spend $30,000 on a heating system he makes $1,500....They want you to spend money....

Also because geo equipment isn't super common it is more prone to fail. I had a Water-to-water unit go bad after 3 years...…

Good Luck, we are all learning and would like to hear how it turns out.

So I'm back, for obvious reasons I didnt break ground in 2021, but I'm back at it in 2022, for one this is a DIY house, so not to worried about someone elses profit margins, the cistern design is 12k gallons, my calculations are 1.5 million btu capacity, the heat loss calculations on the house are like 80k btus an hour. But they also do those heat calcs at worst case scenario, which for me is like -15 degrees 8 hours of sun light a day, in reality we have great weather most of the time. But for the times it does get that cold I plan on a waste oil boiler in the garage that can heat the floors in the house as well, and 2 wood stoves in the house and possibly looking at making them heat the water and possibly adding heat to cistern. Also looking at how to dispose of the cistern water once it gets to 35 degrees. Current thoughts are a second well for disposal, or a septic tank type system with a leech field. Also I'm using water out of the cistern for the house, and it will be topped off by the well, adding a few additional BTUs everyday, the thought on the 12k gallon cistern is it will get me through most months without having to empty it but once every week or two, and in the bad days I might have to empty in once a day, and refill to reheat the house and recharge thermal mass. It's a complicated system but so simple at the same time. Just dont want to invest all this money and screw up. Might need to try it on a small scale first, maybe build a smaller house with a scaled down version.

There isn’t a positive Return on Investment (ROI) for residential ground source heat pump systems. So you are just throwing away lots of money. Perhaps look at an air source to water heat pump system if you really want hydronic radiant floor heating using electric. A gas mod con boiler would be lower acquisition cost and maybe even lower operational cost too depending on your electric and gas rates. And if your electrical rates aren't crazy, even a low cost NextGen electric boiler designed specifically for hydronic radiant floor heating might be a reasonable option. Perhaps give this a read:

http://www.greenbuildingtalk.com/Forums/tabid/53/aff/12/aft/86467/afv/topic/Default.aspx

Yes, a 12,000 gallon cistern operated between 50F (well water supply temp) and 35F (desired heat pump source cutoff temp) gives you 1.5M Btus as you indicated.

At your 99% outdoor temp design condition and assuming your 80K Btu/H load calculation is correct, your 1.5M Btu cistern heat source will be depleted in less than 19 hours. You will need a well that can provide 10.5 GPM continuously or some higher rate intermittently. Using this much fresh well water just to create a heat source seems incredibly wasteful to me...and would be an illegal use of water in my State...

Yes, 99% of the time, less than 80K Btu/H will heat the building adequately. But 1% of the time, more than 80K Btu/H will be needed to adequately heat the building...

Instead of adding heat that is already in the building to an outdoor cistern, it is far more efficient to just keep and use this heat in the building... And don't forget about the electrical power required to pump all this water...