Results 1 to 7 of 7
  1. #1
    Join Date
    Nov 2005
    Location
    Madison WI
    Posts
    4

    Matsu****a rotary compressor backspins

    I had a maintinence man call me and describe what sounded like a broken compressor. It's a First Co. hotel unit. The condenser was dirty and compressor was near max LRA. Rated for 6.6, running at 6.3. On shutdown, compressor had a wicked backspin, rattling and knocking for 15-20 seconds. I figured "this is easy, dirty condenser coil." After cleaning, it runs cooler and RLA dropped to a proper 5.0. But the comp. still backspins loudly. I don't have operating pressures as this is a sealed system w/no access valves. Temp drops are about 16 degrees and the "touch" of the lines tells me it is properly charged. Operates properly except for the rattle. Do these small 1.5 ton units have a built in check valve to prevent this from happening?

  2. #2
    Join Date
    Mar 2010
    Location
    Kent, WA.
    Posts
    189
    I had a 3/4 ton water source heat pump with a rotary compressor do this. It would work great but when it shut off the refrigerant head pressure would spin the comp backwards and it made quite the racket. Considering this was a bedroom unit in a closet of an apartment building i had to replace the unit. I believe the compressor might have a valve on the discharge and when its not sealing anymore consider it das kaput.
    Experience
    Is what you get when you didn't get what you wanted.

    A positive attidude will not solve all your problems, but it will annoy enough people to make it worthwhile.

  3. #3
    Join Date
    Apr 2007
    Location
    Pa
    Posts
    758
    check valve is bad. Instaleld a 50 ton carrier and the new compressor did this. Carrier ate that one and replaced the compressor and paid for the crane and all!

  4. #4
    Join Date
    Jan 2008
    Location
    Dallas ,Texas
    Posts
    3,724
    Quote Originally Posted by HvAckid82 View Post
    check valve is bad. Instaleld a 50 ton carrier and the new compressor did this. Carrier ate that one and replaced the compressor and paid for the crane and all!
    Was it a Copeland?
    UA 100

    It takes three people to do anything around here. Two do the work, one explains to the crowd of people who showed up when they seen smoke and flames.

  5. #5
    Join Date
    Apr 2007
    Location
    Pa
    Posts
    758
    No danfoss

  6. #6
    Join Date
    May 2010
    Location
    Oxford, UK
    Posts
    343
    If its just the faulty internal check valve thats wrong with the compressor, an external one fitted in the discharge line can be worth considering.

  7. #7
    Join Date
    Nov 2005
    Location
    Madison WI
    Posts
    4
    Thanks guys. I was fairly certain that was the problem but wanted confirmation. I think rotaries should be outlawed. Noisy and seem to be very fragile as far as talking abuse such as slugging. They must be very cheap to build.

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