I have no affiliation with B&D, but I like them alot.
the no pressure system has a resevoir mounted above the circulating pump where the air can escape from the closed loop system. This eliminates the need for a flush cart when filling a closed loop. The level can be monitored through the sight glass and refilled with a hose if it gets low. WaterFurnace just unveiled their new design and it looks like it will take care or a lot of problem loops where air just seems to never get flushed out and takes out a pump now and then
These are Accredited Installers I spoke to. One seemed to put the decision of how deep to drill on the Driller because he claimed the driller has been doing this for 20 years and he is the expert. I shying away from this guy because I feel he should be dictating these things to the driller. The other Installer wants to fill from the bottom up with Bentonite. He hasn't said how deep yet other that he will do it in two holes, he is waiting until he comes Monday to look over my system and get all the needed specs. I do like this better, I just wondering about the Bentonite fill he likes to use.
I typically spec. a 150 ft deep well per ton, all connected to a reverse return header grouted form the bottom up with thermally enhanced grout.
My well driller and I are both Internationally Accredited loop installers and he does his best to give me what i spec. but no ground site is the same so he can only do his best with the conditions.
If I have space, I always do a horizontal loop with a backhoe. The results always seem to be better for cheaper, and the variables can be seen with the naked eye. Its hard to tell what is happening with a bore hole hundreds of feet below the surface