Small and crude GSHP for a Michigan garage

[pick1e]

Originally Posted by Ron342

Great Work - But I think you will be limited in your depth if not by the rocks then by hitting water sand which will flow & sift out of your digger ears on the way up! That happened to me at ~ 22 ft Whats your water table at??

Thanks! That's a good point. I don't know exactly where our water table is but it shouldn't be very deep. I'm in the flats of Michigan that used to be lakebed. A friend told me his family had a 17ft water well on a farm half an hour from here.

If I ran into the flowing sand I wonder if I could throw some of the really sticky silty stuff I've dug up so far down the hole and mix it up in order to make it solid enough to bring up on the auger.

Whereabouts are you? Did you install a system or just experimenting? I'd love to know the details. Sounds like you went down pretty far but maybe for something else since you mention an air unit below?

Originally Posted by Ron342

You will also quickly find you need a 3 leg tripod with a pulley to pull out the digger as I did. Plan on having large hairy arms!

No doubt! I'm already thinking of a derrick apparatus at only 7 ft. My arms are puny so far.

Originally Posted by Ron342

I did find though that a 8-10 hp pump with 1 or 1 1/2 pipe ending with a nozzle at about 70 - 100 psi will jet down as far as 60-80 feet really quickly if you don't hit roots or rocks bigger that say 1 1/2 in.I hit marine clay there which ended it. Its a quick way to blow down some holes - dig a trench back from the hole to a pit for the return water to go and settle for the pump suction hose - fill it before you start and during as you'll loose some.

Can I borrow yours? Did it bring up the rocks or go around them? I'd like to try this but would hate to blow a couple hundred bucks if it didn't work. Did you use a pump made for a pressure washer or designed for a different purpose? How about the head?

Originally Posted by Ron342

I think copper is great if you have it around, 1" copper though will cost at least $25 per 10 ft - many times more that HDPE Copper is certainly easier to solder in a U joint and makes a nice straight drop - but I also think the critics are right that most soil has such low conduction that you will need more hole than you think - unless you can tap into a long strata of water with maybe some movement! I believe the conventional wisdom is 200 ft of hole per ton which I think is 12,000 btu

200ft per ton is what I hear with PE pipe. I'm shooting for half that with copper. I figure if soil is normally between 1 and 2 W/m-K and they are figuring 200ft with PE pipe which is about 0.5 W/m-K then at worst I should be able to double the heat extraction with copper instead of PE, thereby halving the required length to about 100ft per ton. We'll see though. I can always add more later.

Originally Posted by Ron342

I have wondered about running the cold refrigerant line of my outdoor heat pump (air) unit through a long trough in which the ground water is pumped to pick up ground heat (Just as a supplement) before it goes into the coil in my outside unit. This wouldnt require going into the refrigerant line - but haven't had the nerve to try it.

You mean basically running warm ground water over the evaporator? I think it would probably ice up like mine did pretty quickly. That wouldn't be much of a problem though if you made your own evaporator coil. As I recall the thermal conductivity of ice is actually higher than soil, just that if you ice up your current evaporator you eliminate the surface area of the fins.

Originally Posted by Ron342

Keep up the great work and posts - but damn its cold there.

Thanks! and yes.