Guide For Homeowners - Loop Design & Questions For Contractors

[Colorado1]

All,

Is there any guide to loop design/geothermal system design for the home owner? Basicly need a check listed for reviewing contractor proposals and policing the installation of the loop/geothermal equipment.

To date, I have three proposals each for a 3 ton unit but different vertical loop set ups: two vertical 300 ft loops, three 200 ft vertical loops and four 150 vertical loops. Which is best?

Any info is apprecited

[crash11]

Did any of them mention pipe diameters or flowrates? For a 3 ton closed loop system it is generally recommended to have 9 gpm overall. So if that 9 gpm is split amongst 2,3, or 4 loops, you want to make sure the pipe diameter is correct for the flowrate in each loop.

2 loops = 4.5 gpm per loop = 1" pipe
3 loops = 3 gpm per loop = 3/4" pipe
4 loops = 2.25 gpm per loops = not recommended

You can't achieve proper turbulence with 2.25 gpm in 3/4" pipe. It's possible the installer intends to use 1/2" pipe for this, but I doubt it. It's not a very popular size.

The 3 loop configuration seems the most reasonable to me, assuming the installer intends to use 3/4" pipe.

You'll also want to make sure the installer intends to grout each hole from the bottom up, and plumb the loops in a "reverse-return" configuration.

[geodean]

there is some info posted here

[arc8]

All,

Is there any guide to loop design/geothermal system design for the home owner? Basicly need a check listed for reviewing contractor proposals and policing the installation of the loop/geothermal equipment.

To date, I have three proposals each for a 3 ton unit but different vertical loop set ups: two vertical 300 ft loops, three 200 ft vertical loops and four 150 vertical loops. Which is best?

Any info is apprecited

Question to designers: Do you think pressure drops are nominally the same across all manufacturers? if they are the same type (water to air, etc) and the same capacity (3 tons, etc)? or are there some brands that have better pressure drops than others when all else are similar?

Colorado: to answer your question; without knowing the brand and model and bore size pipe and soil type and without using my software program, I believe the 300' bores would give better reynold numbers. You need some head pressure to create a higher reynold's number.

To sum it up: to better extract and reject heat from a loopfield, you need the right amount of flow and velocity (the correct reynold's number).