Geothermal heat pump

[skyking]

Originally Posted by Piwoslaw

There is a GREAT thread on geothermal heat pumps over at EcoRenovator. If you could share any details about your GSHP it would be appreciated

Will do, I'll get plenty of photos and explanations. The area is quite dry and I worried about the soils drying out over time and losing efficiency. bad contact, etc.

I'll backfill the coils with 2' and compact, grade level and put in a grid of 4" drain pipe on 6' centers to a header. I'll connect the yard drain and downspout drains to that so we can keep things nice and moist without wasting water.

I'll be regrading the lot, and digging for the addition/garage.

[dr200]

i have loked and read about geo-thermal (means i don't know jack). but i thought goverment was trying to discourge the pump out and pump back in the ground system. been to a few home shows where the push closed loop systems and the major cost seems to be inground installing of the tubes. which an engineer has to figure the delta formula to know length of run (FM, friggin magic ). any way why can't somebody come up with a way to use your existing coils and put it in a tub then circulate your gound source coolant. i left that vague but can you see where i am going?

[skyking]

The contractor we are dealing with has his own formula for the size of coil: figure out the ton needs per the climate data, and make it bigger. My brother's system would work with 2.5 tons. He is getting a two speed 3 ton.
600 ft loop of 3/4 pex per ton. 1 square foot per foot of pipe. 1800 square foot excavation 6 feet deep.
His system will run most of the time as a 1.5 ton.

[sid]

The governments (local, state, and federal) are discouraging open loop systems. There are many reasons, such as problems with hard water deposits, people just dumping the outflow into the storm sewer, or watering their lawns in places with water shortages and restrictions. I installed my original system back in 1980. Since I am putting my outflow back in the ground and I haven't had any deposit problems, when I replaced my heat pump in 2004 my system was grandfathered in. My original system cost $3000, total, including air handling duct work (I already had a well and pump, so they only had to add the return wells), and the new replacement heat pump cost $3300 minus a utility rebate.

[skyking]

Indeed, no way would I try an open loop system around here, water is getting short!

[skyking]

We have the hole about 90% to finish grade. I found some lovely surprises, an un-located sewer line to a neighboring house that we had to repair which also displaced our grid.
The other surprise was caliche, a form of hardpan. I got into it at about 3 feet. The first three feet came off easily with the smooth bucket, but I had to use the 3' digging bucket with tiger teeth to get into it and dig the last 3 feet down.
I'll post some pictures tonight or tomorrow with some of the pipe laid out, hopefully.

[skyking]

I posted a thread with some photos over at EcoRenovator.
New geo system install - EcoRenovator

[smck]

Originally Posted by skyking

The contractor we are dealing with has his own formula for the size of coil: figure out the ton needs per the climate data, and make it bigger. My brother's system would work with 2.5 tons. He is getting a two speed 3 ton.
600 ft loop of 3/4 pex per ton. 1 square foot per foot of pipe. 1800 square foot excavation 6 feet deep.
His system will run most of the time as a 1.5 ton.

That's a ton of excavation. We put in a 3 ton unit from Carrier a year and a half ago and did the vertical loop method. 3 six inch holes core drilled 160 ft deep 10 ft apart buried 4 ft deep from loops to house. Wasn't really all that invasive.

[skyking]

That's not what your wallet said

I would have billed about 3500 for this job if I were doing it.