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  1. #1
    Join Date
    Dec 2009
    Location
    Central Florida
    Posts
    15

    Solar Assisted A/C

    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?

  2. #2
    Join Date
    Mar 2008
    Location
    Baltimore MD and Ridgebury PA
    Posts
    542
    Can you give us info on the manufacturer of the unit?

  3. #3
    Join Date
    Feb 2010
    Location
    Ontario Canada
    Posts
    1,341
    Ya, I would like some technical information on this unit. I have never heard of it and would love to know the theory behind it.
    Never give up; Never surrender!

  4. #4
    Join Date
    Dec 2010
    Location
    Palm Beach,Fl.
    Posts
    990
    Without seeing any technical documents this sounds like an absolute engineering disaster. Compressors are cooled by the cool vapor that is produced during the cooling of the evap coil. Adding excessive heat to the low side of the system will destroy the compressor and make cooling impossible. Suction pressure should be no higher than 150 psig on any 410a system.

    The only solar assisted unit i'm aware of is made by Lennox and all it does is produce power for the outdoor fan. Definitely need some more info on this one.
    Quote Originally Posted by k-fridge View Post
    The laws of physics know no brand names.

  5. #5
    Join Date
    Feb 2010
    Location
    In a boiler room
    Posts
    7,224
    Quote Originally Posted by SoFlaDave View Post
    Without seeing any technical documents this sounds like an absolute engineering disaster. Compressors are cooled by the cool vapor that is produced during the cooling of the evap coil. Adding excessive heat to the low side of the system will destroy the compressor and make cooling impossible. Suction pressure should be no higher than 150 psig on any 410a system.

    The only solar assisted unit i'm aware of is made by Lennox and all it does is produce power for the outdoor fan. Definitely need some more info on this one.
    Agree with this post except I would like to point out that the Lennox Sun Source outdoor units are entirely powered by solar and when not running that solar energy is fed back to the panel to be used by the rest of the house.

  6. #6
    Join Date
    Dec 2010
    Location
    Palm Beach,Fl.
    Posts
    990
    Everything i've read about the sun source units say it powers the fan and feeds back to the utilities. Aren't those panels only 190 watts a piece? I'll have to take another look.
    Quote Originally Posted by k-fridge View Post
    The laws of physics know no brand names.

  7. #7
    Join Date
    Dec 2009
    Location
    Central Florida
    Posts
    15
    The system is advertised by Sedna Aire USA.

    They have a very vague "How it works" on the site.

    I've found more information at the following:
    http://www.ecolinegroup.com/index.ph...Technology.htm

    The air handler and outside unit are both made by Westinghouse (FT4BF Series). The only thing Sedna appears to provide is the thermal collector.

    Photo

  8. #8
    Join Date
    Feb 2010
    Location
    In a boiler room
    Posts
    7,224
    Quote Originally Posted by SoFlaDave View Post
    Everything i've read about the sun source units say it powers the fan and feeds back to the utilities. Aren't those panels only 190 watts a piece? I'll have to take another look.
    That was the 1st generation Sun Source that could only run the fan motor. The new ones can have up to 15 panels hooked to each outdoor unit. 190 watts is right which gives you about 12 amps 240 volt with all 15 panels.

  9. #9
    Join Date
    Dec 2010
    Location
    Palm Beach,Fl.
    Posts
    990
    AH! Good to know, thank you sir.
    Quote Originally Posted by k-fridge View Post
    The laws of physics know no brand names.

  10. #10
    Join Date
    Feb 2010
    Location
    In a boiler room
    Posts
    7,224
    Quote Originally Posted by Bobberly View Post
    The system is advertised by Sedna Aire USA.

    They have a very vague "How it works" on the site.

    I've found more information at the following:
    http://www.ecolinegroup.com/index.ph...Technology.htm

    The air handler and outside unit are both made by Westinghouse (FT4BF Series). The only thing Sedna appears to provide is the thermal collector.

    Photo
    Looks like the latest version of snake oil for A/C units. Did the manufacturer of that new a/c unit know this was installed when they provided a warranty compressor?

  11. #11
    Join Date
    Dec 2010
    Location
    Palm Beach,Fl.
    Posts
    990
    I'd love to hear Lynn Comstocks take on this. I keep looking at the diagram and reading the claims and I can't seem to find anything about this product that's based in thermodynamics. I also don't see how this can be applied to any refrigeration system without causing massive head pressures and eventual compressor failure.

    Discharge gas leaves the compressor super-heated so adding further heat to the system can only reduce its capacity. It honestly looks like something that was intended to be a joke. No offense to the OP.
    Quote Originally Posted by k-fridge View Post
    The laws of physics know no brand names.

  12. #12
    Join Date
    Dec 2009
    Location
    Central Florida
    Posts
    15
    Quote Originally Posted by chuckcrj View Post
    Looks like the latest version of snake oil for A/C units. Did the manufacturer of that new a/c unit know this was installed when they provided a warranty compressor?
    Sedna provided the compressor as a "courtesy." When I checked part numbers I realized there was nothing special about it at all; it was a typical Copeland 2 stage. I have zero warranty support on this now, from both Sedna or Westinghouse.

    @SoFlaDave: I wish it was a bad dream I could wake up from at this point. The thing is I know dozens (if not hundreds) of these units have been sold over the years. I found the very first install back in 2009: http://www.theledger.com/article/200...NEWS/905085021

  13. #13
    Join Date
    Dec 2008
    Location
    Buffalo NY
    Posts
    3,145
    Same here. Why would you add MORE heat? No wonder it killed the compressor.



    Quote Originally Posted by SoFlaDave View Post
    I'd love to hear Lynn Comstocks take on this. I keep looking at the diagram and reading the claims and I can't seem to find anything about this product that's based in thermodynamics. I also don't see how this can be applied to any refrigeration system without causing massive head pressures and eventual compressor failure.

    Discharge gas leaves the compressor super-heated so adding further heat to the system can only reduce its capacity. It honestly looks like something that was intended to be a joke. No offense to the OP.
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