Page 1 of 2 12 LastLast
Results 1 to 13 of 21
  1. #1
    Join Date
    May 2011
    Location
    Houston, Texas
    Posts
    67

    How's Dual Compressors work?

    Hello, need some help explaining this situation. A customer of mine has a game room that works on ONLY one unit with dual compressor. He initially has two workable packaging units, but for whatever reason only one is now hooked up to the building. Because of the heat load inside the building, the compressor #1 will tripped and he has to go and reset the high pressure switch. It will run for about five minutes and tripped and the compressor #2 kicks in. The second will keep running and never tripped. Compressor #1 seems to govern the ductwork around the thermostat area and when tripped will blow out hot air. Compressor #2 seems to govern the middle part of the room and blows out cool air. In addition, he has invested two portable units that are hooked up around the opposite wall of the thermostat because there are no air duct around that area. Okay, so here’s a few of his questions:

    1. How do these two compressors work hand in hand with each other? Are there two separate coils for each compressor – one feeding to one area of the room and the other to the other area of the room?
    2. Why is compressor #1 keeps tripping and compressor #2 never trips? Can we conclude that compressor #1 is bad?
    3. If we replace compressor #1, will we resolve the problem? Can we take the compressor from the other unit (one that is not hook up) and replace it onto compressor #1?
    4. Why is the section around the thermostat area hot when compressor #1 tripped and the middle section stays cool? When not tripping all areas is cool.

    I really need some guidance because I can’t seem to explain it clearly to him. Please help.

  2. #2
    Join Date
    Oct 2005
    Location
    Phoenix, Arizona
    Posts
    380
    1. sounds like you need to go to your friends shop and inspect all the equipment for yourself.
    2. you need to guage up to the unit and see what your pressures are to see why the #1 compressor is tripping.
    3. your asking for trouble if you start gutting unit to fix another
    4. who knows. check supply duct dampers to see if any are closed

    in conclusion if your not a certified hvac tech. you need to call a professional
    RTFM!!!

  3. #3
    Join Date
    May 2011
    Location
    Las Vegas, Nevada
    Posts
    100
    All repairing, testing and subsequent addition or removal of refrigerant should be done by qualified and EPA-licensed refrigeration technicians.

    **Resetting the safety switches repeatedly sound like a great way to cook the oil, contaminate the refrigerant and/or otherwise burnout the compressor.

    If you want it to last, pay for a service call.

    Hope this helped.

  4. #4
    Join Date
    May 2011
    Location
    Houston, Texas
    Posts
    67
    I am a certified HVAC technician by the way, but haven't been in the business for a long time. Well let me simplified the question then since the previous work was probably a hacked job. Can anyone explained dual compressor, how it works and how it hook up to the evaporator coil?

    I've read somewhere that it's a 2 stage compressor, compressor #1 kicks in and work and compressor #2 kicks in if there's more heat load. In that case, can we assumed that compressor #2 will NEVER kick in if compressor #1 will ALWAYS satisfied the heat load. In other word, compressor #2 will never be in used. And also in that case, we can assumed that in this scenario (I'm talking about this customer) it's time to replaced compressor #1 and also fix the heat load issues in the building.

    Greatly appreciate any details!!!

  5. #5
    Join Date
    May 2004
    Location
    SE Pennsylvania
    Posts
    927
    Dual compressor system may be have separate evap coils and refigeration systems or they may share the refrigeration circuit. Either way they are staged according to load compressor 1 may not always be first on, if lead/lag is being used. You may have each compressors refrigeration circuit feeding two different air handlers. Doubt you have bad compressor if you can trip the high pressure safety.

    Certified and qualified or completely different animals.

  6. #6
    Join Date
    Aug 2009
    Location
    Beatrice, NE
    Posts
    2,101
    How it works will depend on what type of system it is. With what you have discribed I would guess there are individual circuits for each compressor, but it may not be the case.

    Tip: Know what you are working on before you try to fix it. If you don't know, wallk away. I have been in this business 33 yrs, I always want to try to learn something but I also know when to walk away.

  7. #7
    Join Date
    May 2011
    Location
    Houston, Texas
    Posts
    67
    Thanks for the info KLS and HVAC69.

    So what you guys are saying is that this unit (with 2 compressors) can either be hooked up to one evap coil or two individual evap coils. I'm getting the feeling that this unit is hooked up to two individual coils because compressor #1 keep tripping and the area around the thermostat is hot while the middle area of the room is still cool and that compressor #2 never trips.

    But guys, you haven't explain how dual compressors work?

  8. #8
    Join Date
    Feb 2011
    Location
    OH
    Posts
    149
    it works off a 2 stage stat when the temp in the rm can not hold than it will start 2nd stage when trouble shooting at first think of them as seperate units ,r,s.e.s says better knowledge through education i hope this helps

  9. #9
    Join Date
    Dec 2010
    Location
    Palm Beach,Fl.
    Posts
    981
    I'm confused, is there 2 compressors or 1 dual speed compressor?

  10. #10
    Join Date
    May 2011
    Location
    Spring City, Pennsylvania, United States
    Posts
    190

    Question

    Sounds like from the op its 2 compressors, 2 circuits. And one circuit is going out on high head. But imo sounds like compressor is fine. More likely that condenser is dirty or something along those lines. Seanhoang do you have any more info on the unit or operating pressures, sh, sc, anything like that...the more the better

  11. #11
    Join Date
    May 2011
    Location
    Houston, Texas
    Posts
    67
    This one unit houses 2 compressors and the one closes to the nameplate is tripping every 5 minutes and high pressure switch has to be reset. Initially it was overcharged with 85psi low side and 300psi high side and increasing. We recovered some of the refrigerant down to 75psi and I don't remembered the high side, but the unit wasn't tripping, but is wasn't a hot day. Then a week later, when the weather got hotter, compressor #1 starts tripping again.

    I am just curious if this unit is hooked up to two individual evaporator coils because the section of the room where the thermostat is is hot when tripped. Or is it just hooked up to one evap coil.

  12. #12
    Join Date
    May 2011
    Location
    Houston, Texas
    Posts
    67
    Oh by the way, we clean the condenser but didn't get the superheat or subcooling readings.

  13. #13
    Join Date
    May 2011
    Posts
    19
    if the suction was 75psig on a cool day it might still be over charged, but knowing super heat and sub cooling would be nice and if you just look in the attic you should be able to figure out if there are two evaporators cooling that room

Page 1 of 2 12 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Comfortech Show Promo Image

Related Forums

Plumbing Talks | Contractor Magazine
Forums | Electrical Construction & Maintenance (EC&M) Magazine
Comfortech365 Virtual Event