The Homemade Heat Pump Manifesto

[AC_Hacker]

Originally Posted by superlen

I seem to recall that you can't fuse pex so I would be left with a mechanical connection that most likely will cause some issue sometime in the future. I thought about bringing the 3/4" up nearer the surface (18-20") at the connection point to the supply/return and making that connection in a box so that I could easily inspect/repair if necessary. 95% of the loops would still be at 6' of course. This would require 5 boxes and a small portion of the supply/return lines to be at 20" depth. I would then drop back to 6' deep on the 200' way out and back to the loop field from the house to pick up whatever additional heat transfer I could gain in transit. That amount of heat exchange might be small due to laminar flow in the larger pipe.

That's right, can't fuse PEX. I even tried... will not work.

So that leaves you some kind of physical connections. Whatever you use will most likely go inside of the piece(s) of PEX so you don't want to reduce the diameter any more than needed. I've seen brass barbed connectors that might do it. The more acidic your soil, the faster the corrosion, so if you know the pH it could help. Also, if it is possible to obtain (make) stainless steel barbed connectors, that would give you a chance. I used some stainless steel hose clamps on some very wet-duty applications, and the clamp itself was resistant to corrosion, but the screw was the problem. If you can get 100% SS hose clamps you might be OK.

As to the rest, it looks like you did your homework, so your guess will be an educated one.

-AC