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  1. #1
    Join Date
    Feb 2011
    Location
    Irmo, SC
    Posts
    9

    pressure discrepancy - heat pump

    ok so a guy i work with (seriously, a guy i work with, not myself haha) was talking to me about an issue he was trying to diagnose. went to a heat pump call for a freezing condenser coil. pressure was low, so he added freon, then checked it in heating and cooling modes, and found a big discrepancy. pressure was too high in one and too low in the other mode (not sure which). a few people in the office think it is the reversing valve. the others think the filter dryer needs to be replaced. what would be a good way to find out? reasoning tells me that the bes idea is to first replace the dryer since it is a far less expensive and less labor intensive part to replace. but it would be better to be able to diagnose it more accurately before doing anything, especially since the unit is out of warranty. if a reversing valve is sticking, wouldn't the "swoosh" sound be absent? or have clicks or something? thanks in advance.

  2. #2
    Join Date
    Apr 2007
    Location
    Langley, BC, Canada
    Posts
    371
    You need to know what the superheat and subcooling temperatures are...without those, your just guessing and replacing parts. I bet you its not the filter dryer, but the temperature difference across it will let you know that.
    Last edited by Crazy4thenucks; 03-04-2011 at 05:14 PM. Reason: grammer
    *Proud To Be a Member UA LOCAL 516*

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  3. #3
    Join Date
    Feb 2006
    Location
    Tn.
    Posts
    1,331
    Quote Originally Posted by Crazy4thenucks View Post
    You need to know what the superheat and subcooling temperatures are...without those, your just guessing and replacing parts. I bet you its not the filter dryer, but by taking the temperature difference across it, will let you know.
    Yes, more info. is needed to know whats wrong.
    Could be neither of the two things he mentioned.
    We would need pressures and temp. at different locations to help you.

  4. #4
    Join Date
    Jan 2010
    Location
    Hunts. Al.
    Posts
    349
    could be that metering thingy

  5. #5
    Join Date
    Jul 2002
    Location
    Yuma, AZ
    Posts
    2,361
    Could be airflow, yadda, yadda.
    "I have never let my schooling interfere with my education."
    Mark Twain
    More at: http://www.quotationspage.com/subjects/education/

  6. #6
    Join Date
    Jun 2007
    Location
    Round Rock
    Posts
    2,919
    I doubt it is the filter dryer being clogged. The only time I've had a clogged filter dryer is when the tenant of a house, who was a minister. Had a member of his congregation out who did a/c to check the system out and he would give him a couple of bucks to help him out. He was down and out. Somehow this guy got lots and lots of dirt into the system and told the guy/landlord he needed a new system. Ungodly amount of dirt into it. We got called out and cleaned things up. I had to go back about 6 months later and change out 2 clogged filter dryers.
    I like DIY'ers. They pay better to fix.

  7. #7
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
    Posts
    10,538
    Quote Originally Posted by snooked321 View Post
    could be that metering thingy

    Plus One...

    For the OP: Folks can talk about "what it might be" until the cows come home. Until there's real data gathered, that's all it is...talk.
    "In this house we obey the laws of thermodynamics!"

    - Homer Simpson

  8. #8
    Join Date
    Dec 2001
    Location
    Ocean Pines, MD
    Posts
    6,909
    Quote Originally Posted by shophound View Post
    Plus One...

    For the OP: Folks can talk about "what it might be" until the cows come home. Until there's real data gathered, that's all it is...talk.

    In other word, see Sonic's threads.

  9. #9
    Join Date
    Dec 2005
    Posts
    1,655
    Quote Originally Posted by narfhead22 View Post
    ok so a guy i work with (seriously, a guy i work with, not myself haha) was talking to me about an issue he was trying to diagnose. went to a heat pump call for a freezing condenser coil. pressure was low, so he added freon, then checked it in heating and cooling modes, and found a big discrepancy. pressure was too high in one and too low in the other mode (not sure which). a few people in the office think it is the reversing valve. the others think the filter dryer needs to be replaced. what would be a good way to find out? reasoning tells me that the bes idea is to first replace the dryer since it is a far less expensive and less labor intensive part to replace. but it would be better to be able to diagnose it more accurately before doing anything, especially since the unit is out of warranty. if a reversing valve is sticking, wouldn't the "swoosh" sound be absent? or have clicks or something? thanks in advance.
    It is best that your company call a proffesional out to diagnose the problem. Who knows - you may and your company can learn some too.

  10. #10
    Join Date
    Dec 2002
    Location
    SouthEast NC ICW & Piedmont Foothills
    Posts
    7,254
    what were operating conditions?

    narf...............pay attention at this point, if you stick around here and advance, these are going to be pieces of info you will need to bring to the table the first time, getting info to try and solve an issue should not be like pulling hens teeth
    It`s better to be silent and thought the fool; than speak and remove all doubt.

  11. #11
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
    Posts
    10,538
    Quote Originally Posted by Stamas View Post
    In other word, see Sonic's threads.
    LOL!
    "In this house we obey the laws of thermodynamics!"

    - Homer Simpson

  12. #12
    Join Date
    Apr 2010
    Posts
    21
    check line temp before and after dryer , temp difference means pressure difference.

  13. #13
    Join Date
    Jul 2002
    Location
    Yuma, AZ
    Posts
    2,361
    Quote Originally Posted by gzone53 View Post
    check line temp before and after dryer , temp difference means pressure difference.
    I never saw that work on a cap tube system.
    "I have never let my schooling interfere with my education."
    Mark Twain
    More at: http://www.quotationspage.com/subjects/education/

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