Results 1 to 7 of 7
  1. #1

    "Little David" Pressure Switch? What is this guy?

    This is on a compressor in a central rack refrig system. Does anyone know what this guy does?

    http://picasaweb.google.com/ericjhwi...36540619706690

  2. #2
    Join Date
    Feb 2007
    Location
    Texas
    Posts
    40
    Looks like a cheap pressure activated anti short cycle switch to me.

  3. #3
    Join Date
    Apr 2007
    Location
    maryland
    Posts
    24
    it is time delay controller for the startup of the compressor. it allows the unit to have sufficent static pressure before the compressor can start up. It is mostly used as safety device to prevent overloading of compressor startup amps.

  4. #4
    Join Date
    Oct 2002
    Location
    Lady Lake, Florida
    Posts
    799
    I've seen some simular to those used on small tonnage yorks for a lo-pressure bypass timer to allow time to build back pressure on start up in lo ambient conditions for units cooling computer rooms. Basically added to them in the field ar some point.

  5. #5
    Join Date
    Feb 2007
    Posts
    28
    its an anti short cycle switch -- as long as the pressure switch is closed and the jumper time is satisfied, comp should run -- cuts out comp at contactor

  6. #6
    Join Date
    Feb 2003
    Location
    NH & Cebu
    Posts
    1,608
    I worked for a company in the '80's that installed some here and there.
    They were marketed as a way for the stores to save energy. We installed a new LP control to control the compressor, and set it so the compressor would maintain a higher back pressure, so when it ran, it was under full load. Then the timer would keep it from short cycling.

    We would also install a clock to record compressor run time. I'm not sure if any customers ever saved anything by using them.

  7. #7
    Join Date
    Dec 2007
    Location
    Indianapolis
    Posts
    677
    Quote Originally Posted by hvacmd2002 View Post
    I worked for a company in the '80's that installed some here and there.
    They were marketed as a way for the stores to save energy. We installed a new LP control to control the compressor, and set it so the compressor would maintain a higher back pressure, so when it ran, it was under full load. Then the timer would keep it from short cycling.

    We would also install a clock to record compressor run time. I'm not sure if any customers ever saved anything by using them.
    Yup. Nailed it. My Dad was in a position to sell some to some local Mickey D's and had one installed on on of their W/I units. Just a shame one of the regional directors came along even after he had showed them I believe about $200 month savings and said -"Nope not corporate approved - take it off!!"


    Coulda made a mint -<sigh>

    B-

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