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  1. #1

    320 PSI Head Pressure No matter what?

    What will cause high head even after doing the following. I wont go into all the reason's why some of this was done. The relevant issues to my question was that these things have been done and I still have high head pressure.

    (1). (original service call)
    Unit was just charged a week ago by another company but it has leaked down again. (determined indoor coil was leaking). Charged the unit up and ordered the new coil to put in tomorrow. When I charged the unit the suction pressure was 75 psi and head was 325 psi. 15 degrees superheat. I decided to go ahead and clean the condenser since I was putting a new evap coil tomorrow. Cleaned the coil and head pressure dropped to 310 PSI. Guess I've got non-condensibles in the system. Tomorrow I'll recover all the refrigerant and pull a good vacuum and take care of it then.

    (2). Next day I changed the indoor coil. Pulled a lengthy vacuum. Changed the pump oil before pulling the vacuum. Doing this by the textbook.

    (Summary) After all of this the unit is still running 310 psi head. 75 suction - Indoor temp at this time was about 87 degrees. Getting an 18 degree TD. 15 degree superheat at the condenser.

    If suction pressure is ok and both coils are clean and good airflow at the vents what else could be causing this head pressure?

    Any ideas are very much appreciated!

  2. #2
    Join Date
    Aug 2005
    Location
    San Diego,CA
    Posts
    285
    Are your service valves completly open??? tonage? model?
    Sink or Swim!
    A Man has to know his limitations..
    To be old and wise, one must be young and dumb..

  3. #3
    Valves are open. 3 Ton goodman. 3 ton coil. Correct piston size checked.

  4. #4
    Join Date
    Feb 2008
    Location
    Western NC
    Posts
    2,504
    Is it a double-stacked OD coil? Is so, theres a good chance that there is crap in between the 2 layers.

    Whats the subcooling? Fan motor RPMs? Fan blades bent? Fan blade positioning?
    I fully support the military and the War on Terrorism.


    If you don't know, then don't do. If you don't know and still do, then be prepared to pay someone else a lot to undo what you did and then do it right.

    If you do know, then do. But do it right. Otherwise, you may not be doing it long.

  5. #5
    Join Date
    Mar 2001
    Location
    North Carolina
    Posts
    428
    What was your micron gauge reading at end of vacume and was it steady?
    Model #'s of both out door unit and coil?

  6. #6
    Join Date
    Aug 2005
    Location
    San Diego,CA
    Posts
    285
    Yeah, check that condenser fan motor and see if its getting hot... I had a carrier unit with head pressure just like yours, the motor was getting really hot. I changed it, and shes running steady.
    Sink or Swim!
    A Man has to know his limitations..
    To be old and wise, one must be young and dumb..

  7. #7
    Iraq, Thank you for your service to our country. I really appreciate it!

    Great question about the double coil. I will double check that but I'm almost sure this is not a double layer coil. As far as the model # of indoor and outdoor unit I dont have that in front of me. As I replace major components I always go back with OEM parts. This is a goodman 3 ton unit with a goodman replacement evap coil for the 3 ton condenser recommended by the manufacturer. I believe its a CK-36-1A? 2004 model. Unit was still under warranty. This unit delivers 1310 CFM by manufacturer spec. To measure the actual CFM I would need a psychrometer to convert the wet bulb to enthalpy and I didn't have one with me. (AH!!! Condenser fan motor... That one slipped my brain) I'll check that too... You guys are good! Keep the ideas coming.

  8. #8
    Join Date
    Aug 2004
    Location
    North Richland Hills, Texas
    Posts
    14,915
    What was the air temperature entering the condenser coil?
    If more government is the answer, then it's a really stupid question.

  9. #9
    Join Date
    Aug 2005
    Location
    San Diego,CA
    Posts
    285
    whats the seer ratings??
    Sink or Swim!
    A Man has to know his limitations..
    To be old and wise, one must be young and dumb..

  10. #10
    I would have to check ARIdirectory.org for the rated SEER but its probably actually 9 on a good day. Pardon my ignorance by asking you this question. How does the SEER rating affect my high head pressure problem?

    Ambient air temp was around 95 degrees. This unit is located in central mississippi.
    Last edited by superdave44; 07-31-2008 at 02:48 AM.

  11. #11
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
    Posts
    11,376
    Some of us older farts remember when 300+ head pressures was nothing out of the ordinary.

    In your case, did you factor in a house temperature at 87 degrees? That's a hell of a high heat load for a system designed to hold ~75 degrees. What was your indoor entering wet bulb temperature as well?

    Go back and remeasure this system once the house pulls down to customer's setpoint. I think you'll find your head running lower at that point.

  12. #12
    Join Date
    Feb 2008
    Location
    Sharpsville, PA
    Posts
    27
    Quote Originally Posted by superdave44 View Post
    I would have to check ARIdirectory.org for the rated SEER but its probably actually 9 on a good day. Pardon my ignorance by asking you this question. How does the SEER rating affect my high head pressure problem?

    Ambient air temp was around 95 degrees. This unit is located in central mississippi.
    the higher the seer rating the lower the head pressure will be

  13. #13
    Join Date
    Feb 2008
    Location
    Sharpsville, PA
    Posts
    27
    Quote Originally Posted by shophound View Post
    Some of us older farts remember when 300+ head pressures was nothing out of the ordinary.

    In your case, did you factor in a house temperature at 87 degrees? That's a hell of a high heat load for a system designed to hold ~75 degrees. What was your indoor entering wet bulb temperature as well?

    Go back and remeasure this system once the house pulls down to customer's setpoint. I think you'll find your head running lower at that point.
    haha just the other day i came across a 40 year old westinghouse condenser. 355 head pressure.

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