AC Pump relay

Discussion in 'Electrical Stuff' started by jmauld, Mar 9, 2023.

  1. jmauld

    jmauld Well-Known Member

    Jun 9, 2020
    Carolina Beach
    2010 Sundancer 390
    2016 Sea Hunt Ultra 211
    Twin 8.1l of gas guzzling iron
    Can someone give me a rundown of how this system works or how it is wired?

    I see the relay box behind the electrical panel. I’m half blind and have trouble reading it. But it looks like it’s rated for 25A. I assume that’s the switched load rating.

    My schematics don’t show how this system is wired, but when my AC turns on, that relay adds very little current draw. Is it providing 120V to the water pump? Is it safe to assume that pump pulls little power?
     
  2. electricaldoctor

    electricaldoctor Well-Known Member TECHNICAL Contributor

    May 14, 2008
    Thousand Islands, Rockport, Ontario.
    1988 390 EC
    454 Mercruiser Gassers
    Check to verify the pump voltage. Don't be surprised if it is 12 Volts.
     
  3. jmauld

    jmauld Well-Known Member

    Jun 9, 2020
    Carolina Beach
    2010 Sundancer 390
    2016 Sea Hunt Ultra 211
    Twin 8.1l of gas guzzling iron
    I’m guessing that’s the case. I’ll take a better look tonight but there were some substantial AC lines running through the box, which was confusing me. I’ll open it up again and spend more time on it.
     
  4. ttmott

    ttmott PhD in OCD TECHNICAL Contributor

    Apr 3, 2012
    Space Coast Florida
    2006 52 Sedan Bridge
    Cummins QSM11
    I think you will find the raw water pump to be 120VAC or 240VAC (like mine) and that pump is turned on and off by the Dometic Cruiseair Pump Relay box. For each air conditioning unit on the boat there will be a "trigger" installed in that relay box. When one of the HVAC units demand cooling or heating it first sends a signal to the trigger to start the pump then five seconds later starts the compressor. Each HVAC unit can independently turn on/off the raw water pump; that is the purpose of that relay box.
     
    dtfeld likes this.
  5. dtfeld

    dtfeld Water Contrails GOLD Sponsor

    Jun 5, 2016
    Milton, GA
    410 Sundancer
    2001
    12" Axiom and 9" Axiom+ MFD
    Cat 3126 V-Drives
    Just curious if your having and issue??

    The actual schematic is inside the lid of the pump relay box. The "triggers" are wired to each AC unit you have. There are 115VAC and 220VAC triggers depending on you AC units. These are replaceable items for about $60 each.

    Power for the pump comes from the AC panel, through the relay box, then out to the pump.

    upload_2023-3-10_10-8-10.png
     
  6. jmauld

    jmauld Well-Known Member

    Jun 9, 2020
    Carolina Beach
    2010 Sundancer 390
    2016 Sea Hunt Ultra 211
    Twin 8.1l of gas guzzling iron
    No issues. Just doing some re-balancing of my panel so that I can put inverter loads on one line. Trying to figure out how much of a load the pump system demands.
     
    dtfeld likes this.

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