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Thread: No SH, low SC, Suggestions?

  1. #21
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    Evaporator can’t make ref subcooled, at best you would have saturated, unless you are able to change science.

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  3. #22
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    Quote Originally Posted by RedSafety View Post
    10 ton 3 phase Goodman R22 heat pump. No superheat, about 2 degrees subcooling on vapor side. 24-26 amps on the compressor, 30 rla. It's a bugger to get inside the unit, AND it's not even 1' away from the wall and another unit 3 feet away, maybe. so:

    Need some help here. My plan of attack, based on ease of checking:
    After checking with the manufacturer to see if its safe on this particular unit to do a draw down check the compressor. Will it draw down to 0 psig.
    Next check the reversing valve. Voltage, magnatism, smack it, check temperatures on the legs.
    Last, check the txv.

    Thoughts? Suggestions?
    Head pressure-165 psi. (outdoor ambient?)

    The attachment suggests a flooding system.


    Does the suction line show signs of flooding? press R to show the actual T1 value, what is the suction line temperature at the coil outlet?

    Check Both coils. Check filters. Check ID blower/ OD fans.

    Check pressures after doing this to see if readings change.

    If readings don't change and RV is functioning properly,

    Check expansion valve for proper size, Check bulb insulation and contact. If it is adjustable, I would first:

    Recover the charge and weigh back in the nameplate charge. Take readings again. If the charge was already correct and everything was proper try closing the indoor expansion valve to raise the SH.

  4. #23
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    Ambient was about 95.



    Filter was filthy after a major cleaning in the area. Filter grill is on the ground. Yes, touching the floor, and LOTS of foot traffic. However, these readings are after the filter change. No felting of the coil.

    Just looked at the diagram again. Check valve across the TXV malfunctioning?????

    Beginning to suspect the TXV is stuck open. Royal pain to get to as I have to do a major disassembly on the outdoor unit to get to it. Easy to get to from above, but then can't run the unit.

  5. #24
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    Quote Originally Posted by ehsx View Post
    Evaporator can’t make ref subcooled, at best you would have saturated, unless you are able to change science.
    Actually I think I saw that once, the only thing is I didn't have test equipment on to check for sure.

    The condenser fan quit, hot gas was passing through the condenser coil into the evap where it was cooled. There was enough liquid coming back I assume to keep the compressor from going off on IOL or internal pressure relief valve.

    I have only seen it that one time so an odd situation.

  6. #25
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    Quote Originally Posted by BNME8EZ View Post
    Actually I think I saw that once, the only thing is I didn't have test equipment on to check for sure.

    The condenser fan quit, hot gas was passing through the condenser coil into the evap where it was cooled. There was enough liquid coming back I assume to keep the compressor from going off on IOL or internal pressure relief valve.

    I have only seen it that one time so an odd situation.
    Heat would have to be removed, not added. Evap acting as condenser…

  7. #26
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    Quote Originally Posted by RedSafety View Post
    Ambient was about 95.



    Filter was filthy after a major cleaning in the area. Filter grill is on the ground. Yes, touching the floor, and LOTS of foot traffic. However, these readings are after the filter change. No felting of the coil.

    Just looked at the diagram again. Check valve across the TXV malfunctioning?????

    Beginning to suspect the TXV is stuck open. Royal pain to get to as I have to do a major disassembly on the outdoor unit to get to it. Easy to get to from above, but then can't run the unit.
    What about the bulb? Does it react to temperature? Have you pulled the charge to record the existing system charge to see if that checks out?

    Does closing the valve a half of turn show any difference in return gas temperature or head pressure?

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  9. #27
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    Quote Originally Posted by ehsx View Post
    Heat would have to be removed, not added. Evap acting as condenser…
    Yeah the rest of the space was conditioned so the evap was cooling the refrigerant vapor but since I hadn't gauged up I don't know how much. But the compressor was not overheating on a roof with no cond fan running on a sunny summer day.

  10. #28
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    One of the two inside TXVs was evidently stuck wide open. One had condensation and the other was warm. Now my gauges are leaking. Liquid is bleeding off into the compound gauge, per sight glass. Rebuild kit will be in on Friday. I now have superheat though. Will have to check the DT.

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  12. #29
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    8.7 degree difference between the two TXV circuits. Only about 16.7 DT across the inside coil.

  13. #30
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    You can’t have a stuck open txv and low vapor pressure, without low airflow.

    Low airflow, low refrigerant.

    Get your airflow where it should be, your superheat and vapor pressure will come up.
    Temp drop will decrease. Add charge.

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  15. #31
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    Quote Originally Posted by BNME8EZ View Post
    No SH, lo SC, all your refrigerant is stacked up in the evap. Could be a matter evap, belt slipping, motor running backwards, supply damper closed or return also. Possible metered g device over feeding.
    This is a must before making any txv adjustments.

    Especially that blower orientation.

    It really seems like you are not moving air.

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  17. #32
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    Moving lots of air. and why would there be so much temperature difference between the two TXVs from the same feeder circuit? The bulbs are inches away from each other, only about 3-4 inches from the Y in the feed line?

  18. #33
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    Too many things going one, including safety and security issues. Just got back to the system. Neither interior TXV is responding to hot water. 2 TXVs in parallel. Temps are backwards.

    Liquid line - 78.4.
    TXV1 "octopus" line - 46.8
    TXV2 "Octopus" line - 43.0
    Vapor line - 38.7

    Shouldn't the vapor line temp be higher than the TXV feeds? Is it in heat mode possibly?

  19. #34
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    Is your 'octopus' line the distributor tubes where the liquid refrigerant has not had time to fully expand? If so, this is not a spot we usually measure temp.


    Quote Originally Posted by RedSafety View Post
    Too many things going one, including safety and security issues. Just got back to the system. Neither interior TXV is responding to hot water. 2 TXVs in parallel. Temps are backwards.

    Liquid line - 78.4.
    TXV1 "octopus" line - 46.8
    TXV2 "Octopus" line - 43.0
    Vapor line - 38.7

    Shouldn't the vapor line temp be higher than the TXV feeds? Is it in heat mode possibly?
    I do a triple evac with nitro to remove non condensables.

    I'm feelin' a little peculiar.

  20. #35
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    Yes, the distribution tubes.

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  21. #36
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    You need to start over and a plain description of the situation.
    You said,
    Heat pump,something about changed to hot water.
    165# head pressure, no ambient given,97 the next day post.
    Dirty filters,no mention of a visual on the evaporator coil Inlet side.
    No confirmation on proper blower Rotation or drive condition.
    Your all over the place buddy with crazy Temps,info,this,that.
    I'm lost as he'll. Appears you are as well.
    First clue is the 165# head pressure in, August........
    A proper set of All the Vitals is Required here.
    Low,Hi side pressures.
    Superheat,Subcool,
    Indoor dry,wet bulb and Outdoor ambient.
    Confirmation on the blower and evaporator coil .
    Heat pump txv's are notorious for failure and may stick in an unfavorable position usually. Possible reason your bulb test failed.
    I'm still interested in the 165# head myself.
    Bless his heart.....

  22. #37
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    People seem to all about the TEMPS on Systems, sh,sc,sat,what ever else you can come up with But,
    If your PSIG's aren't in the ballpark first,your TEMP's don't matter until you figure that out.

    Why was the tire temp so high? Why is the wheel bearing temp so extream,there is an increased transmission temp,Omg???

    Tire had no PSIG....

  23. #38
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    Quote Originally Posted by mrkelly View Post
    People seem to all about the TEMPS on Systems, sh,sc,sat,what ever else you can come up with But,
    If your PSIG's aren't in the ballpark first,your TEMP's don't matter until you figure that out.

    Why was the tire temp so high? Why is the wheel bearing temp so extream,there is an increased transmission temp,Omg???

    Tire had no PSIG....
    If you know the saturation temperature you don't need to know the pressure because it's the same thing. The only time I look at pressures is when I'm going to tell somebody else who doesn't understand saturation temperatures.
    "Is this before or after you fired the parts cannon at it?" - senior tech
    I'm tired of these mediocre "semi flammable" refrigerants. If we're going to do it let's do it right.
    Unless we change direction we are likely to end up where we are going.
    "It's not new, it's better than new!" Maru.

  24. #39
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    I understand saturation Temps but being old school with analog compound gages have the conversion right in front of me mechanically and not depending on an electronic sensor and a battery that may or may not work properly as electronic devices do on a consistent basis. Sure analog can be faulty but it's Obvious when They are.
    You correlate sat temp and I psig apparently. Where as I have to convert to know exactly what your saying the way I'm use to. Because I don't have sat temp memorized to know it at 73# psig but can instantly reference it on my Guage without a t&p chart and know exactly if the need arises.
    Tomato tomatoe.

  25. #40
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    Quote Originally Posted by mrkelly View Post
    You need to start over and a plain description of the situation.
    You said,
    Heat pump,something about changed to hot water.
    165# head pressure, no ambient given,97 the next day post.
    Dirty filters,no mention of a visual on the evaporator coil Inlet side.
    No confirmation on proper blower Rotation or drive condition.
    Your all over the place buddy with crazy Temps,info,this,that.
    I'm lost as he'll. Appears you are as well.
    First clue is the 165# head pressure in, August........
    A proper set of All the Vitals is Required here.
    Low,Hi side pressures.
    Superheat,Subcool,
    Indoor dry,wet bulb and Outdoor ambient.
    Confirmation on the blower and evaporator coil .
    Heat pump txv's are notorious for failure and may stick in an unfavorable position usually. Possible reason your bulb test failed.
    I'm still interested in the 165# head myself.
    Bless his heart.....
    *Heat pump is NOT used as we converted these to use the water boiler system
    *dirty filters, dirty coils. Filters replaced and coil cleaned As Stated Earlier
    *Blower rotation? Its blowing in the classrooms and sucking dirty like a vacuum cleaner off the floor. Need to begin replacing filters monthly. Some idiot put the return directly to the floor and no room to move them up.
    *Yes, I'm lost as hell. The guy I got into this to help, due to almost total lack of use of his right arm due to chemo, died a month and a half after I began helping him. Now I'm on my own. Deal with it! I'm keeping the business running until the widow can find a buyer.
    *You want pressures? Here they are! And critical temps!

    Outside
    Temp DB 94.6°

    Vapor
    Temp 38.7°
    SH .9°
    Pressure 67.9 PSIG
    Liquid
    Temp 93.7°
    SH 3.3°
    Pressure 187.0 PSIG

    Indoor
    Return Air
    DB 76.6°
    WB 61.3°
    Supply
    DB 49.0°
    Temperatures
    Liquid 39.7°
    Vapor 76.6°

    TXV 1 47.5°
    TXV2 47.5°


    Two bizarre changes from previously is the delta Ts on air flow and the 2 TXVs. Air flow delta T was barely 17 degrees previously, but that was before I repaired the supply pendulum that was blown apart. Now it seems the air flow is a major issue. Also, this is the first time the TXV outlet temps are a match. They had been off by a minimum of 5 degrees, up to almost 9 degrees. Neither responds to hot water immersion. They are in parallel, alternating the width of the evaporator coil.

    Also interesting was after getting temps and pressures outside, when I disconnected the high side and tried to bleed the refrigerant back into the system into the low side, it took several minutes for the pressure to drop down. Quite strange.

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