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  1. #1
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    Confused Earthwise Purge Questions

    Hello Everyone,

    First off, this is my first time posting, but I've been gleaning valuable information from this site for a long time so thank you all for sharing your expertise!

    Some quick background on me. I started off in the HVAC world as a duct cleaner, then residential service tech, and now work for a large retail warehouse/logistics/phone center/data center building as their HVAC maintenance guy. That progression happened in about 3 years total, so I love the challenge, but feel a bit behind the learning curve. We have 2 Trane CVHF650's and 1 CVHE450. I'm having trouble with two of the Earthwise purge units.

    1. On the CVHE450, I've been getting increasingly getting surge on startup, sometimes enough to shut the chiller down on "Extended Compressor Surge". I monitor my purge minutes and they have been 0 for the past few weeks. Before that, it was pretty consistent around 12-15 minutes per week. I naively didn't put two and two together to figure out that I, in fact, did not have a perfect chiller, but that my purge unit wasn't working. Here's what I've done so far:
    - At first I suspected a leak, so I recovered the charge (scale said I recovered about 8oz) and pulled a vacuum. It came down to ~800 microns in pretty short order (under an hour) and maintained it when valved off. At that point I thought I must have made a mistake so I weighed 10 1/2 oz of 404a back in (If I understood the manual correctly, that is the factory charge).
    - With the charge weighed in, the unit still does not purge. The compressor and condenser fan run. The suction pressure runs between -4psi and 0psi. If I understood the manual correctly, the trigger for the pump-out compressor is the superheat as measured by the compressor suction line temp sensor (As non condensibles accumulate in the purge tank, there's less coil available for superheating so the low superheat turns it on if I understand right). My temp measurement of that sensor is within a degree of what the chiller reads, usually in the low to mid 70's. I couldn't find anywhere in the manual that said what the threshold temp is for that pump out compressor to turn on is. I tried packing it with ice, just to see if I could get it to turn on- got it down to ~40F but it didn't kick on. I was able to get my hands on Trane's Techview software and go in and do a test on the pump out compressor and it worked fine for the test.
    - At this point, I'm a bit confuddled. My residential brain is looking at what I perceive as low suction pressure and crazy high superheat and screaming "Low refrigerant!" but I just weighed in the charge. (to be fair, I'm beginning to become suspicious of the scale they have here. I've caught it a few times when I'm weighing in refrigerant, that the weight of the tank keeps decreasing slowly even after its been valved off)

    Any help there would be appreciated. What am I missing?

    2. On one of our 650's I've got a pretty good sized leak coming through the threads of the little float switch on the bottom of the purge tank. I've tried taking it out and slathering it with leak lock and putting it back in as tight as I feel comfortable without breaking something but it continues to leak. Is it time for a new purge tank? Or once again, am I missing something simple?

    Thanks again! Let me know any details I might have left out that you need.

  2. #2
    Join Date
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    if your running that low of suction pressure your drier has probably came apart and plugged up the expansion valve, seen it a lot with the purifier purges over the years, change the drier and the expansion valve, recharge and I'll bet your good to go.

    The pumpout pump turns on when the suction line temp hits 18 degrees and turns off at 22 degrees.

    Throw that can of leak lock in the trash and get some Loctite 554.
    Last edited by chillrdude; 06-23-2017 at 09:29 AM.
    If you dont stand behind our troops, please feel free...........to stand in front of them.

  3. #3
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    I believe I would have put the sensor in ice bath before I stated messing around with the red charge

    Get new float switch, run tap in hole, clean with alcohol, apply 554

  4. #4
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    Thread Starter
    Thanks a ton to you both! That helps a lot.

  5. #5
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    The easiest way to check the refrigeration circuit on a purifier purge is right after servicing the purge with new drier cores or the inline filter drier, while the purge is isolated from the chiller pull a vacuum on the purge and then start the purge, since there is no refrigerant in the purge chamber and nothing to condense you should be able to watch the purge suction temp drop until the pumpout pump turns on, it wont shut off until you open the valves to the chiller and allow refrigerant to enter the purge chamber, then the suction temp rises and off goes the pump.
    If you dont stand behind our troops, please feel free...........to stand in front of them.

  6. #6
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    You should have a constant 17psig suction pressure. Make sure you don't have a temperature drop across the filter drier.
    I think the temps chillrdude was saying is for the older purges. An earthwise purge with a CH530 is different. It calculates it off purge liquid temp. It pumps out when suction temp is 50 below liquid temp and stops at 40.

    Sounds like you've got a good grasp on things. Keep it up!

    BTW, you've got mail.
    Last edited by BennyD; 06-23-2017 at 10:30 AM. Reason: Typo
    -----Stop, step back, relax and have another go at it.-----

  7. #7
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    Thread Starter
    Never would have thought of that on my own. Thanks chillrdude!

  8. #8
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    Thread Starter
    Thanks BennyD!

  9. #9
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    Quote Originally Posted by chillrdude View Post

    The pumpout pump turns on when the suction line temp hits 18 degrees and turns off at 22 degrees.

    Throw that can of leak lock in the trash and get some Loctite 554.
    Hes working on an Earthwise , not the same temp for pump out cycle and please toss the leak lock and do not use that red loctite crap either . Teflon tape and or white teflon pipe dope is more than enough.
    The toy chest is officially full ... I got a new toy..... 2007 Aston Martin V8 Vantage and yes it still gives me goosebumps
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  10. #10
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    Like Benny said, you should have a constant 17 PSI on the suction side. The purge uses an automatic expansion valve, not a thermostatic expansion valve. A thermostatic expansion valve (like we usually see) regulates to maintain superheat. An automatic expansion valve maintains a constant pressure and the superheat varies due to load on evaporator. That's why there is no sensing bulb. You probably need to replace the drier and expansion valve, then evacuate and weigh in the exact amount of R-404A. Also get rid of the piercing valve, that's a leak point and the purge only holds 0.6 lb of refrigerant. Use a solder in schreader valve. Also, make sure you charge liquid only and take into account of the refrigerant in your hoses. When I work on purges, or any fractional HP refrigeration system, I use a pinch off tool and pinch off, cut out schreader valve, and braze closed to hermetically seal the refrigeration system and eliminate the leak point at the schreader valve.

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