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  1. #14
    Join Date
    Sep 2002
    Posts
    11,542

    What a great idea!

    So the oil filled solar collector on the roof adds heat to the outdoor circuit to augment the system's heating ability?

    How is that roof collector isolated from the system when the system is functioning for cooling?

    Who makes this system? Make? Model? Serial?

    On what basis is the compressor being condemned? Pumps too much?

    PHM
    -------






    Quote Originally Posted by Bobberly View Post
    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?
    PHM
    --------
    The conventional view serves to protect us from the painful job of thinking.

  2. #15
    Join Date
    Sep 2002
    Posts
    11,542

    Holy dog poop Batman!

    I read though that mumbo-jumbo description of their process on the supplied website links - and it sure sounds a whole lot like nonsense. "preferentially absorbs hot molecules" ??? <g>

    What did the salesman say to you before you bought this thing?

    At your first post I thought they were using a solar collector to add heat to the outdoor portion of a heat pump system - when in the heating mode. Which is a great idea - I do it myself.

    But that does not seem to be what they are saying.

    Where are they using the R-407C ? Is that in your entire system? Compression cycle and all? Or is it being used only as a phase-change medium in the solar collector?
    PHM
    --------
    The conventional view serves to protect us from the painful job of thinking.

  3. #16
    Join Date
    Apr 2008
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    Pa.
    Posts
    1,010
    the collector is a compressor also....i wonder if a lack of thermal dump of some sorts may have been why flared joints failed...it gots to hot...maybe not controlled properly among other things..the concept could work but having the compressor in series seems like a sure failure...u can use a flame in place of a compressor so why not a collector?

  4. #17
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
    Posts
    11,086
    Boy do these people not understand basic vapor compression refrigeration!

    To wit from link above:

    The Sedna Aire Solar Absorption Air Conditioning System uses a different method. It uses the solar heat from the sun to superheat the refrigerant which enables the refrigerant to begin changing state at the top 2/3rd's of the condenser coil. By using this method it reduces the superheat of compression


    BS. If I'm seeing this in my head correctly, they're talking about sending hot gas off the compressor through a solar powered superheater? And that's supposed to reduce head pressure on the compressor...how?


    The conventional air conditioning system is only able to change a portion of the gas into a liquid state so as when the refrigerant enters into the metering device it is a saturated vapor.
    Incorrect. By the time refrigerant reaches the metering device in a properly operating system, it is a subcooled liquid, not a saturated vapor. Adding heat post compression but pre condenser only assures that there will be less subcooling, if any. Could even do something as crazy as have saturated vapor at the metering device, exactly opposite to what they claim occurs with conventional a/c.


    The Sedna Aire process allows more of the refrigerant to change state back into a liquid faster as well as allowing the transformation of more liquid into the metering device.
    I'm calling BS again. The following sure doesn't bode well for long compressor life:

    • Electricity makes refrigeration happen.
    • Refrigeration makes the HVAC psychrometric process happen.
    • HVAC pyschrometrics is what makes indoor human comfort happen...IF the ducts AND the building envelope cooperate.


    A building is NOT beautiful unless it is also comfortable.

  5. #18
    Join Date
    Sep 2002
    Posts
    11,542

    use a flame in place of a compressor?

    Which compression cycle refrigeration system uses a flame in place of a compressor? <g>

    PHM
    ------




    Quote Originally Posted by farbeondriven View Post
    the collector is a compressor also....i wonder if a lack of thermal dump of some sorts may have been why flared joints failed...it gots to hot...maybe not controlled properly among other things..the concept could work but having the compressor in series seems like a sure failure...u can use a flame in place of a compressor so why not a collector?
    PHM
    --------
    The conventional view serves to protect us from the painful job of thinking.

  6. #19
    Join Date
    Feb 2010
    Location
    In a boiler room
    Posts
    6,914
    Quote Originally Posted by Poodle Head Mikey View Post
    Which compression cycle refrigeration system uses a flame in place of a compressor? <g>

    PHM
    ------
    I am going to say no compression cycle uses a flame, am I right? Absorption cycle does.

    I read somewhere on how this is supposed to work, the compressor is not used at the same time as the solar.

    Sedna Air paid for the new compressor? Sounds like an admission of a serious flaw to me.

  7. #20
    Join Date
    Dec 2010
    Location
    Palm Beach,Fl.
    Posts
    920
    The compression cycle and absorption cycle are totally different animals. How does the refrigerant circulate through the compressor without it operating? The only thing that can move the discharge valve in the compressor is a differential pressure.
    Quote Originally Posted by k-fridge View Post
    The laws of physics know no brand names.

  8. #21
    Join Date
    Apr 2008
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    Pa.
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    1,010
    Quote Originally Posted by Poodle Head Mikey View Post
    Which compression cycle refrigeration system uses a flame in place of a compressor? <g>

    PHM
    ------
    You knew what I was talking about...slick

  9. #22
    Join Date
    Dec 2009
    Location
    Central Florida
    Posts
    15
    Quote Originally Posted by Poodle Head Mikey View Post
    So the oil filled solar collector on the roof adds heat to the outdoor circuit to augment the system's heating ability?

    How is that roof collector isolated from the system when the system is functioning for cooling?

    Who makes this system? Make? Model? Serial?

    On what basis is the compressor being condemned? Pumps too much?

    PHM
    -------
    The roof collector is used for both heating and cooling, there is no isolation mechanism, despite any diagrams indicating that one might exist. I posted the mfg and the model of the unit they rebranded in an earlier post.

  10. #23
    Join Date
    Jul 2008
    Location
    Rochester NY
    Posts
    4,632
    ... He must have a camper!... (kidding)

    I recall reading they make ice in remote villages in Africa with solar absorption chillers.
    Which makes more sense to you?
    CONSERVATION - turning your thermostat back and being uncomfortable. Maybe saving 5-10%
    ENERGY EFFICIENCY - leaving your thermostat where everyone is comfortable. Saving 30-70%

    DO THE NUMBERS! Step on a HOMESCALE.
    What is comfort? Well, it AIN'T just TEMPERATURE!

    Energy Obese? An audit is the next step - go to BPI.org, or RESNET, and find an auditor near you.

  11. #24
    Join Date
    Dec 2009
    Location
    Central Florida
    Posts
    15
    Quote Originally Posted by chuckcrj View Post
    I am going to say no compression cycle uses a flame, am I right? Absorption cycle does.

    I read somewhere on how this is supposed to work, the compressor is not used at the same time as the solar.

    Sedna Air paid for the new compressor? Sounds like an admission of a serious flaw to me.
    Yeah, but I didn't dare hook up the collector again.

    There are no controls (since the unit is stock) to turn the compressor off while still running the evaporator fan and condenser fan. The only way cooling happens is when the compressor is running (dying).

    I assumed that because the side of the unit had Sedna on it that they had actually engineered something, then I discovered their branding was applied as a sticker.

    Better yet, here's one of their vendors advertising where you can clearly see the rebranding:
    http://www.amplusairconditioning.com...r_conditioning

  12. #25
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
    Posts
    11,086
    I'm reposting this:




    To show why, IMO, it is utter nonsense. Even with some assumptions I'll make regarding what I'm seeing here, I don't think anything could arise to sway my opinion differently.

    The solar collector is supposed to raise the refrigerant temperature much higher than the compressor alone can do, correct? And by so doing it would then be much higher over ambient than by vapor compression and the heat content of the refrigerant coming from the evap, right? Is that the concept?

    If so, here's where it falls apart. Pressure extends in all directions, not just in the direction of refrigerant flow. So the solar collector, as shown on the diagram, is imposing one MASSIVE elevation of head pressure against the discharge side of the compressor. I don't care if that device shown on the diagram just downstream from the compressor is some kind of heat exchanger. That's even more ridiculous if it is. Taking discharge superheat and dumping it into the suction vapor? That's insane. Hope that's an open drive compressor! Even so you'd be cooking the comp oil with this setup. Same for a hermetic compressor...go over 250 degrees sustained discharge temp and it's no wonder the compressor could die.

    And then, if my eyes don't deceive me...this company doesn't even make their own equipment? They take new OEM stuff and do this to it? How's that work from a warranty standpoint? What OEM in their right mind would support a discharge heat exchanger AND a solar collector elevating head pressure prior to the condenser?
    • Electricity makes refrigeration happen.
    • Refrigeration makes the HVAC psychrometric process happen.
    • HVAC pyschrometrics is what makes indoor human comfort happen...IF the ducts AND the building envelope cooperate.


    A building is NOT beautiful unless it is also comfortable.

  13. #26
    Join Date
    Dec 2009
    Location
    Central Florida
    Posts
    15
    The consensus I've seen so far from everyone is that it is impossible for this configuration to deliver anything as advertised, and doubtful that it could do anything but cost MORE money given the load on the compressor.

    I'd still like to know the rating of the flare fittings to at least counter the their claim that it wasn't an installation defect.

    If anyone is near Central Florida and wants to do some experiments with the thermal collector in the name of science please let me know. I never did get a chance to measure max pressure/temp since I kept having the R410A blow out. The collector does a wonderful job of absorbing heat, just poor use with air conditioning.

    Edit: Apparently the collector also qualifies as "Solar Energy Property": http://www.pepsolar.com/Sedna%20Aire...atement-18.pdf

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