GeoThermal Heat Pump

[t5800512]

American Standard is a good brand. But I'm not sure if I have can get them. I have always stayed inside the Carrier product line. Their (Carrier) top of the line variable speed compressor model is something like 20.5 SEER. Did you catch the model number or name of the American Standard unit. No big if you did not, I can probably find it.

[t5800512]

I'm still looking at the GSHP. The new WaterFurnace 7 series has an EER of 41. Not SEER, EER of 41, and a COP of 5.3. It is just hard to argue with that kind of numbers. The only thing that comes close are the Mini-Split systems.

[Naptown]

At what ground temperature and fluid temperature in the loop.
If intake temps remained the same throughout the heating or cooling season COP would be stable throughout but with the heating and cooling of the fluid it will change.
How much I do not know.

[t5800512]

According to the tables, the ground temperature in this area is 69 degrees. I have been talking to someone that has a GSHP system in my area, and that is about what he is seeing as well. He has seen the temperature on his loops go up a couple degrees in three years, but there has been no noticeable loss of efficiency.

I'm going to make sure my ground loop wells are at least 20 feet apart to help avoid the heat island effect.

[Naptown]

All well and good however how well does the soil dissipate and transfer heat.

[t5800512]

Good point, and I don't know how to answer that other than to say that the local drillers and geo folks believe that one ton will be dissipated by a 300 foot deep well. So 4 wells yields a 4 ton system.

[inetdog]

Good point, and I don't know how to answer that other than to say that the local drillers and geo folks believe that one ton will be dissipated by a 300 foot deep well. So 4 wells yields a 4 ton system.

They may be relying on a knowledge of a local geology which is pretty uniform once you get past the surface layers. Especially if the water table is consistent (rather than varying will elevation and location) and much less than 300 feet deep.

A horizontal pipe loop will be much more subject to variation, since it is in the surface layers.

[bcroe]

The thing in the frozen North, is the air to air system can't function below outside
freezing, so you are into resistance heat that part of the year. My research
indicates your electricity is multiplied about twice by air to air, 4 times for
the buried system, compared to resistance.

An installer here indicated a couple trenches could be dug, then TUNNEL multiple
times between them instead of digging up large areas in a surface system. Not
sure he understood how much rock is here near the river (but not near enough
to use!). Bruce Roe

[Sunking]

You have TX Black Gumbo heavy clay soil. Water can barely move through it. Yankees have loam soil and very porous where water can freely move through it, not to mention shallow ground water levels.

[bcroe]

You have TX Black Gumbo heavy clay soil. Water can barely move through it. Yankees have loam soil and very porous where water can freely move through it, not to mention shallow ground water levels.

The thing that worries me most, is all the flat yellow rock found just below the surface. Like, 50% of the
stuff before you reach the frost line. Pretty hard to tunnel, trenching works. Perhaps I should show some
of it to the tunneling installer? Need to check water level. Bruce Roe

[Sunking]

Bruce I am no geologist, but water flows freely in quite a few of rock sediments.

[inetdog]

The thing in the frozen North, is the air to air system can't function below outside
freezing,...

Actually it can work just fine if the relative humidity is low and the unit does a periodic defrost of the evaporator coil.
The worst case condition is when you have humid air just above freezing or supersaturated air just below freezing.

[russ]

Actually it can work just fine if the relative humidity is low and the unit does a periodic defrost of the evaporator coil.
The worst case condition is when you have humid air just above freezing or supersaturated air just below freezing.

The COP just drops off toward 1 as the temperatures drop.

To me, what counts is my cost at the end of the month. A COP of 3 cuts your bill by 3 times as compared to electric resistance heat. A COP of 4 cuts it by 4 times so a 100 dollar bill becomes 33$ and 25$ respectively. 8$ per month savings from 3 or 4 months a year doesn't pay for much in the way of wells or ground loop, landscaping etc.

[russ]

The thing that worries me most, is all the flat yellow rock found just below the surface. Like, 50% of the
stuff before you reach the frost line. Pretty hard to tunnel, trenching works. Perhaps I should show some
of it to the tunneling installer? Need to check water level. Bruce Roe

100% yes and hope the installer knows something about the heat transfer characteristic of that type of earth.

Water level generally doesn't come into play with the trenched loop applications. The soil itself is the heat transfer media.

[russ]

Good point, and I don't know how to answer that other than to say that the local drillers and geo folks believe that one ton will be dissipated by a 300 foot deep well. So 4 wells yields a 4 ton system.

Either local knowledge that or he read it in a brochure somewhere - expensive to screw up.