Maryland System Not Keeping Up

Discussion in 'Maintenance and Troubleshooting' started by dmj2359, Aug 18, 2019.

  1. dmj2359

    dmj2359 New Member

    Recently my Waterfurnace 7 Series (3 Ton) hasn't been keeping up with keeping the house cool. Originally installed in 2012 it has worked fantastic in both heating and cooling seasons until the last week or so, which while warm hasn't been the hottest weather we've had in the mid-atlantic this summer. It's been running wide-open (compressor speed 9, fan speed 10) for a week, but the temperature in all 3 zones of the house (IZ2) has been getting slowly warmer as the week progresses.

    I checked the obvious things I can: filter changed, vacuumed a little dust and dog hair off of the heat exchanger that had crept around the filter. Airflow out of the various vents around the house seems fine. I have an AID tool so can see various performance numbers (will post some numbers in a reply to this post), but nothing jumps out at me as being terribly different from when I have checked before.

    Planning to get someone out this week to check the system over in detail, but just thought I'd check to see if there's anything obvious that jumps out to anyone, and if there is anything I can do to improve the situation in the meantime.
     
  2. dmj2359

    dmj2359 New Member

    Overview:
    Status: Normal
    Mode: Cooling
    Faults: E15 Hot Water Limit
    ECM: 2, 3, 10, 12, -10%
    IZ2 Comp Spd Des: 9
    Comp Spd Act: 9
    IZ2 Blower % Des: 100%
    Blower Spd Act: 10

    Service:
    Drv Supply Volt: 234V
    Line Voltage: 234V
    UDC Voltage: 423V
    Comp Power: 1671W
    Thermo Pwr: 42%
    Inverter Temp: 97.7F
    Drv Temp: 97.6F
    Drv Fan Spd: 53%

    Performance:
    Ent Water: 88.0F
    Lvg Water: 91.4F
    WaterFlow: 12.4 gpm
    Brine: Antifreeze
    Ht of Rej: 20448 btuh
    Loop Press: NA psi
    Ent Air: 83.2F
    Lvg Air: 68.5F

    Sensors & Ref:
    Discharge: 284 psi/159.1F
    Suction: 120 psi/80.4F
    HtgLL: 53.2F
    ClgLL: 92.7F
    Sat Evap: 40.3F
    Sat Cond: 92.4F
    EEV SH/Open%: 40 /100%
    SubCooling: 0F
    CompAmbient: 100.2F
    VS Drv EWT: 87.8F
     
  3. geoxne

    geoxne Active Member Forum Leader

    Heat of Rejection should be around 30,000 BTUH according to Specification Catalog Page 35
    https://www.waterfurnace.com/literature/7series/SC2700AN.pdf
    Suction Pressure is Low
    Discharge Pressure is Low
    Superheat is High
    Subcooling is Very Low
    Waterside DeltaT is Low
    Airside DeltaT is Low

    NV_036Cooling..JPG
    Free Internet Diagnosis - Low Refrigerant Charge (Possible Leak)
    Get a WF trained tech in there. They have access to WF Tech Services and Warranty info and procedures. Digital sensors can be off. All numbers need to be verified at the unit with accurate test equipment for a proper diagnosis.
     
  4. geoxne

    geoxne Active Member Forum Leader

    Probably not.

    SuperBoost cooling mode is available. It will allow the compressor to run up to speed 12 for 24 hrs. However, this will drive system pressures up and risks losing refrigerant at a faster rate if there is a leak.
     
  5. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    Your delta T on the water side is pretty low, although your are over pumping a tiny bit. Thus you are not rejecting enough heat in stage 9.
    There is something wrong with your refrigerant circuit, likely not enough refrigerant.
     
  6. dmj2359

    dmj2359 New Member

    Follow-up: Technician identified that the evaporator coil is leaking. I'm curious what the part cost for a new coil is, knowing that a lot of the replacement cost will be labor and refrigerant. Any ballpark numbers for this - trying to decide how many places to ask for bids vs. just having it done ASAP.
     
  7. gsmith22

    gsmith22 New Member

    wouldn't the unit still be under warranty? thought 7 series was 10 year parts (can't remember about labor)
     

Share This Page