Proper Air Temp Rise on Split System? Site glass bubbles??

Discussion in 'Maintenance and Troubleshooting' started by Geoaid, Dec 29, 2011.

  1. Geoaid

    Geoaid New Member

    I have 2 waterfurnace split system heat pumps. I just recently purchased the house and noticed the stage 2 heat pumps were only hooked up for stage 1. I have now hooked them up for stage 2 however I now get temperature rises of 37F on the ES048 with quite a few bubbles in the site glass (there are bubbles in stage 1 as well (air temp rise of 23)). The other heat pump's ES036 air temp rise is 24F stage 1 and 49Fon stage 2. Not really any bubbles once a good run time is achieved. Any suggestions? Are these temp rises too high? Unfortunately, the heating demand for the house requires more than stage 1, so if I only leave stage 1 hooked up, backup AUX electric is used quite often.
  2. engineer

    engineer Well-Known Member Industry Professional Forum Leader

    Sounds like insufficient airflow in stage 2
  3. Looby

    Looby Member Forum Leader

    It sounds as if your stage1 vs. stage2 "hookup" is an "either-or" choice.
    Doesn't your system automatically switch between stages depending on
    the current load?
  4. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    Bubbles in the site glass

    is just an indication of TGW. Things gone wrong.

    To evaluate a DX, (direct expansion, where a metered flow of liquid refrigerant is allowed to enter the evaporator section, boiling that refrigerant to absorb heat), system. (A system that uses a TXV, thermal expansion valve, to meter refrigerant to the evaporator portion of a system), one needs to have all points of heat transfer clean and operating at design levels.

    Since you just bought the home, you have no clue of the service history. I would find an honest knowledgeable service person, who likes heat pumps and blow the bucks for his high exorbitant hourly or flat rate price to clean then re-commission both units. When a unit is commissioned there is a check list of events and measurements that I doubt 95% of my fellow HVAC contractors do at starting up a system. Except on high end commercial systems I have never in the 35 years I have been making people comfortable have I found commissioning stats.

    So to re-commission a system I pretend I am the guy that started the system and after it is clean, make it do all the numbers listed in the book.


    Interveiw for the job, because when you find the right service person, you will never need another. I would bet my right leg, (the good one), that anyone typing here is great and anyone listed here is very good. Those of us here are above the average. We can read and type.

    Sorry if I got long winded. I am waiting for the Walleyed Pike to drop.

    Great 12

  5. Geoaid

    Geoaid New Member

    site bubbles high delta T

    Thanks for the input. and yes its likely these units were never set up properly. Who knows why the dual stage heat pumps were never wired and set up to function for both stages? But now that I've wired the T-stat and units for ,dual stage the delta-T on the air-side is high. I'm no refridge tech, but ever thing i've read says delta-T should be about 25 F. My question is what happens when the delta-T is more than 25 F. I can't change the fan-speed easily as the 5 tonne unit is single speed and the 3 tonne unit which has a multi speed blower unit is now running at top speed for both stages. Am i faced with getting either more ducting (also not simple as every thing is finished) or buy a higher speed fan. Sounds like i might also need someone to adjust the TXV or re-fridge levels. As for finding someone good on service, what qualifications do you recommend. Thanks for your help. Best for 2012.

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