I had a system that was coined "solar assisted" installed in my home some months ago. The system consists of a standard 2 stage 16 seer heat pump/ac and a thermal collector mounted on the roof. In place where you would normally see a heat recovery unit installed, the thermal collector has been placed. The thermal collector consists of the copper run through glass tubes filled with oil. To visualize:
Compressor -> outside coil -> inside coil -> Thermal collector -> Compressor
Yes, the collector is adding a significant amount of heat into the system (enough that I've burned my hand on contact with the copper). The manufacturer bills this as less work on the compressor, but my own energy observations and other issues with the system have cast some doubt.
In June when the Florida sun finally pushed the temp into the mid 90s the flare fittings gave and I lost about 6lbs of refrigerant. The fittings were replaced with some "gunk" added on the threads and a week later my compressor is making a horrible noise and cutting out. I measured 400psi on the high side and after the compressor came on suction only dropped to about 340, 2 minutes later the compressor shuts down (thermal overload?).
The manufacturer recommended replacing the compressor (not the entire outside unit as I would have thought), and while that was done I have what appears to be a massive leak. It started as a 10psi drop/day and is now at 30psi/day. I can't blame the thermal collector since I had it disconnected when the compressor was replaced, but I'm wondering if pressure could have caused damage elsewhere in the lines.
I've observed the tech going over everything with a leak detector and seen several places where it sounded for 20 seconds and then stopped, after which we couldn't get it to detect a leak in the same spot. The only place we haven't been able to look is the copper lines in a pipe under the slab.
I'm hoping that this community can help me understand my observations and offer theories on the technology. I've got my own battle happening with the manufacturer/dealer/installer, but I don't know enough to ask the right questions or what to suggest to rememdy. The tech was drafted as a friend-of-a-friend on the dealer that sold me the unit, and had never seen one of these systems before. He's trying but isn't getting any answers from the manufacturer anymore on what to do next.
The original specifications I read about used R22 but the higher pressure of R410A has be wondering if this design can still work. My short list of questions are:
What is the design limit for flare/compression fittings?
How does R410A react when superheated in this fashion?
How does the power load on the compressor react to pressure/temperature?
Should I just replace this system with a conventional and let the lawyers sort it out?