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Thread: Heat pump reset

  1. #14
    Join Date
    May 2006
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    Amory Mississippi
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    998
    with the indicated pressures I would be surprised to find an over charge.
    Also rheem has a chart inside the cover so you can check the charge. the tech made a guess the filter drier might be restricted. If that is the case there should be a temp drop across it. I have seen them sweating and icy cold and never tripped the hp switch. In my experience rheem/ruud heat pumps are more sensitive to an overcharge in heating mode than a lot of other brands. I worked for a company that installed hundreds of new ruud heat pumps in new developments. When winter rolled around I had a lot of calls with the pump tripped on the hp switch. Overcharged when installed. (NO I did'nt install them )I found dozens of them overcharged and every one of them the pressure on my gauges reflected the excessive pressure.

    Of course I am assuming that since he said the coils were clean the blower and condenser fan are running and the filter is clean and the other usual suspects have been checked. Since he already replaced the defrost board (and the contactor?) and the defrost board should have come with a new defrost sensor I would think all those bases have been covered. It is still tripping on high pressure.

    I've been wrong before but my money is on the HPS

  2. #15
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    Jun 2007
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    south carolina
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    As far as charge goes it looks under charged 175 psi head on a system with clean coils would put the temp inside between 52 and 62 degrees. unless your an eskimo I dont see that being right.

  3. #16
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    Jul 2005
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    Quote Originally Posted by gsxrsquid View Post
    with the indicated pressures I would be surprised to find an over charge.
    Also rheem has a chart inside the cover so you can check the charge. the tech made a guess the filter drier might be restricted. If that is the case there should be a temp drop across it. I have seen them sweating and icy cold and never tripped the hp switch. In my experience rheem/ruud heat pumps are more sensitive to an overcharge in heating mode than a lot of other brands. I worked for a company that installed hundreds of new ruud heat pumps in new developments. When winter rolled around I had a lot of calls with the pump tripped on the hp switch. Overcharged when installed. (NO I did'nt install them )I found dozens of them overcharged and every one of them the pressure on my gauges reflected the excessive pressure.

    Of course I am assuming that since he said the coils were clean the blower and condenser fan are running and the filter is clean and the other usual suspects have been checked. Since he already replaced the defrost board (and the contactor?) and the defrost board should have come with a new defrost sensor I would think all those bases have been covered. It is still tripping on high pressure.

    I've been wrong before but my money is on the HPS
    I can't count the number of times I've monitored the pressures on Rheems for quite a long time (a half hour or longer) before the head pressure begins to suddenly rise. In heat pump mode an overcharge along with the associated floodback can actually cause low head pressure for awhile until enough of the excess refrigerant boils out of the accumulator, then finally the indoor coil becomes oversaturated to such a point that head pressure begins to spike. Rheems seem more prone to this behavior than other brands. I don't know why, but it just seems to be the case.

    I remember one Rheem HP in particular that I didn't catch it doing this until something like my fifth trip out. On that trip I decided to camp out and watch the thing. It ran for at least a half hour normally before the head pressure spiked. I never once suspected up to that point that an overcharge was causing the nuisance head pressure switch trips. Since that time I've seen exactly the same behavior on dozens of Rheems, but of course none of them fooled me like that first one did. One of the first things I check when the switch is tripped and when the pressures look normal is the liquid level in the accumulator. A cup of water poured on it will show the level with a band of ice below the liquid's surface. Until the accumulator is empty the charge has not been checked.

  4. #17
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    Quote Originally Posted by super_tech_1 View Post
    As far as charge goes it looks under charged 175 psi head on a system with clean coils would put the temp inside between 52 and 62 degrees. unless your an eskimo I dont see that being right.
    If it's running at 175 psig, then it isn't tripping the head pressure switch at 175 psig. It has to be tripping at a higher pressure than that, thus the system must at times run at a higher pressure than that.

    Also, he said "30 F outside and 65 F inside." 175 isn't abnormally low under those conditions for all systems. An overcharge won't show up immediately if all the excess is sitting in the accumulator, so we could even see 175 for quite a while with an overcharge. I'm not suggesting that it's overcharged, just that it's a possibility, and one that isn't all that unlikely. But AFAIK, there hasn't been anywhere near enough info provided to even guess at the cause of the head pressure switch trips. Several possibilities have been given other than a bad switch, and from the OP's input I haven't seen where any of those bases have been covered yet. I doubt from what he posted that the switch has even been tested, which would be the first order of business.

  5. #18

    Heat pump reset

    There has been no freon added or subtracted since the unit was installed 11 years ago. This is the first time I have had it serviced (my bad).

    It has been over 2 days now and the unit has not tripped out. Although it has been a little warmer out, nothing else has changed but the parts already changed: contactor, defrost board and sensor.

    I have not called anyone else out yet (don't know who to call) and will wait to see if problem is over.

    However, the unit still seems to me to be making more noise than it used to - a loud hissing noise that I can't seem to locate while it is heating. I put it in cooling mode and it runs much quieter.

  6. #19
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    That red button is simply a refrigerant high pressure switch. If no freon has been added, and your air filter, both refrigerant coils, and fans are clean, then most likely the switch is going bad. I seriously doubt if there is any damage a tech could do to make it continue to trip.

  7. #20
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    Aug 2006
    Location
    Longview,TX.
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    83
    Seems like about that many yrs. ago Rheem installers had an issue with the plenum opening/configuration. Had to be the same size as the opening or the lips had to be bent up or something like that.

    If they didn't they were constantly having to add ref. in the summer and remove it in the winter or it'd be tripping the high press. re-set.

    But if this is the first time yours has done that then I guess you can ignore this reply.

  8. #21
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    Nov 2006
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    SC
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    If the defrost sensor was starting to fail, high head during defrost could be the result. Since the sensor has already been replaced, it would be hard to say now. A good tech should check the temperatures/pressures DURING a defrost cycle. And test the high pressure switch to see where it trips. Both are simple tasks.

  9. #22
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    Every one of those units (that I saw) had a large bright orange sticker right on top of those flanges. If someone installed a unit without bending those flanges up, they were either an idiot or could not read English.

  10. #23
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    Jun 2007
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    Piedmont Triad, NC
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    You say they unit is making a hissing noise? You also say it has not been serviced in 11 years. What kind of metering device does the unit have? It may not be a bad idea to have the unit superheat/subcooling checked. Make sure it has the correct charge and no restrictions in the metering device.

  11. #24
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    May 2006
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    Amory Mississippi
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    I can't remember if those older units had scrolls off the top of my head. IF it is a scroll that hissing could be the relief valve.


    When the tech was there indoor temp was 65. I wonder what the indoor temp is at it's warmest. Medic is right, if it is operating at 175 head it is not tripping at 175 head. I'd love to check that puppy out but a long way from florida. might be cost prohibitive.

  12. #25
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    Jun 2007
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    Piedmont Triad, NC
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    The hissing you are hearing is probably the unit going into defrost. What happens when the sensor detects ice buildup it sends the unit into defrost. (if the defrost is working correctly) It energises the reversing value and that is the "hiss" sound you hear. The condenser fan will stop but the compressor will continue to run in "cool mode" so the heat can defrost any ice that has formed. When the sensor has detected that it is defrosted it will again reverse the valve back into "heating mode" and the fan will start running again.

    This may not help you solve your problem but at least it will help you understand where the hissing noise could be coming from.

  13. #26
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    Quote Originally Posted by gsxrsquid View Post
    I can't remember if those older units had scrolls off the top of my head. IF it is a scroll that hissing could be the relief valve.


    When the tech was there indoor temp was 65. I wonder what the indoor temp is at it's warmest. Medic is right, if it is operating at 175 head it is not tripping at 175 head. I'd love to check that puppy out but a long way from florida. might be cost prohibitive.
    They've been using all Scrolls since at least the late 1980s. Maybe you can get him to pay you travel time.

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