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Low suction

Discussion in 'Residential' started by jamesyarbrough, Sep 22, 2017.

  1. jamesyarbrough

    jamesyarbrough Amateur Gynecologist

    Messages:
    3,707
    Location:
    Denison TX
    3 ton rheem hp 2000 model. Low suction no super heat. Normal head.

    Pulled and cleaned evaporator and blower. Checked piston size. Moving 1000 cfm.

    85 od 74 id with 60 wb. 230 lbs of head. 18 sc. 59 psig suction 5sh. Delta t is 15.


    Compressor had been changed from a zr34 to a zr 36.


    Can 2k btu make that much difference?
     
  2. Texas-Tech

    Texas-Tech Official Geezer*

    Messages:
    17,627
    Location:
    duhh
    :dunno:
     
    Last edited: Sep 24, 2017
  3. Anita sannich

    Anita sannich Exceptionally average

    Messages:
    554
    Location:
    Spokane WA
  4. Daryl_Dixon

    Daryl_Dixon New Member

    Messages:
    3,780
    Duct static pressure?

    Superheat?
     
    Last edited: Sep 22, 2017
  5. Daryl_Dixon

    Daryl_Dixon New Member

    Messages:
    3,780
    In my experience, yes.
     
  6. Anita sannich

    Anita sannich Exceptionally average

    Messages:
    554
    Location:
    Spokane WA
    If capacity was increased by 6 percent, should refrigerant be increased by 6 percent too?
     
  7. knave

    knave Undeterred

    Messages:
    8,166
    Location:
    Out for a rip
    Airflow should, especially if it had been marginal to begin with.
     
    Anita sannich likes this.
  8. knave

    knave Undeterred

    Messages:
    8,166
    Location:
    Out for a rip
    More load = higher suction and more SH.
     
    Jim54 and Texas-Tech like this.
  9. tuna

    tuna New Member

    Messages:
    2,914
    Maybe a little overcharged. But, I have started drinking. :lachen:

    I'd leave it alone and check on a 90 plus day. :thumb:
     
  10. Anita sannich

    Anita sannich Exceptionally average

    Messages:
    554
    Location:
    Spokane WA
    Is that delta t across the indoor or outdoor coil?
     
  11. R2D2-TX

    R2D2-TX New Member

    Messages:
    443
    Recip or scroll?
     
  12. jamesyarbrough

    jamesyarbrough Amateur Gynecologist

    Messages:
    3,707
    Location:
    Denison TX
    it's a scroll. Super heat was 5. Right on target. But suction was 5 or 10 lbs low. Head was a little high too.

    When I got there before I performed any work it was running 55 lbs of suction and no sh. It got a little better but it still ain't right. I wonder if one of the circuits on the evaporator could be clogged.


    I always think it's airflow. But I pulled all the filters out and it made no difference in suction pressure.
     
  13. jamesyarbrough

    jamesyarbrough Amateur Gynecologist

    Messages:
    3,707
    Location:
    Denison TX

    Indoor
     
  14. Joeysmith

    Joeysmith New Member

    Messages:
    84
    Dryer sheets in the supply registers?
     
  15. Texas-Tech

    Texas-Tech Official Geezer*

    Messages:
    17,627
    Location:
    duhh
    What size piston is in it?
     
  16. jamesyarbrough

    jamesyarbrough Amateur Gynecologist

    Messages:
    3,707
    Location:
    Denison TX
    65. Factory spec.
     
  17. jamesyarbrough

    jamesyarbrough Amateur Gynecologist

    Messages:
    3,707
    Location:
    Denison TX
    Damn thing is oversized for the space. Kinda makes me want to just sell them a new unit and go with a 2.5 ton and enlarge all the returns and shoot for 400 cfm per ton. **** it! Lol
     
    jpb2 likes this.
  18. Texas-Tech

    Texas-Tech Official Geezer*

    Messages:
    17,627
    Location:
    duhh
    :dunno:
     
    Last edited: Sep 24, 2017
    Anita sannich likes this.
  19. Anita sannich

    Anita sannich Exceptionally average

    Messages:
    554
    Location:
    Spokane WA
    Block the airflow on the outdoor unit till liquid pressure reaches #250 lbs, monitor sh and sc to see if they coincide with rise in pressure. That's how I was taught to check charge when outdoor temp is below 85, with piston applications.
     
    freeworld and 404eh like this.
  20. 404eh

    404eh New Member

    Messages:
    196
    Recovery will tell you if it's low. You need a pillow and cigarettes but easy way to cross it off the list