The Homemade Heat Pump Manifesto

[AC_Hacker]

Originally Posted by hikerjohnson

...topsoil for 10-14 inches, followed by seeming bottomless sand, and a water table at no more than 10 feet of depth, sometimes 8 feet if you dig in a low spot...all sand for some tens of feet before he hits ledge.

OK, great!

Originally Posted by hikerjohnson

...I have friends with excavators, so what's the difference between three trenches and four? It's a marginal material cost, to be sure...

Well, the heck with boreholes then.

There was one guy on here named 'rhino' I think, who did trenches for cooling rather than heating (he lives in Florida). The reason I mention this is that he found out that his water table rises and falls. Therefore, the best time to dig your trenches is when the water table is at the lowest point, so you can achieve maximum depth and don't have problems with cave-ins.

Randen did a trench system, I believe he went with straight pipes. Make sure you looked over his work.

You'll also need to be aware of fluid friction and how it is affected by velocity, pipe diameter, pipe length, and viscosity (due to the possible presence and percentage of anti-freeze). Taco, the pump people have some good documentation on this. And of course, the IGSHPA Installation Guide has all this and much, much more.

Best,

-AC