ReplyCan you give us info on the manufacturer of the unit?
Regular Guest
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?
Professional Member*
Can you give us info on the manufacturer of the unit?
Professional Member*
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!
Professional Member*
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.
Originally Posted by k-fridge
Professional Member*
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.
Professional Member*
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.
Regular Guest
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
Professional Member*
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.
Professional Member*
AH! Good to know, thank you sir.
Professional Member*
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?
Professional Member*
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.
Regular Guest
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
Professional Member*
Same here. Why would you add MORE heat? No wonder it killed the compressor.
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Membership Chair/ARP Committee / Professional Member*
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
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PHM
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When faced with the choice between changing one's mind, and proving that there is no need to do so, most tend to get busy on the proof.
Membership Chair/ARP Committee / Professional Member*
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
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When faced with the choice between changing one's mind, and proving that there is no need to do so, most tend to get busy on the proof.
Professional Member*
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?
Professional Member*
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?
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 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.
I'm calling BS again. The following sure doesn't bode well for long compressor life: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.
Psychrometrics: the very foundation of HVAC. A comfort troubleshooter's best friend.
Membership Chair/ARP Committee / Professional Member*
Which compression cycle refrigeration system uses a flame in place of a compressor? <g>
PHM
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PHM
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When faced with the choice between changing one's mind, and proving that there is no need to do so, most tend to get busy on the proof.
Professional Member*
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.
Professional Member*
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.
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