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Thread: Dual Water Pumps / Boats

  1. #1

    Default Dual Water Pumps / Boats

    Greetings Everyone,

    I have a unique setup I haven't seen on here yet. I've even tried a few of the ideas to see if these resolve my problems. But alas, it's still a no go.

    Here's my problem.

    I work on a boat that has two water pumps. One of the pumps works fine now that I've replaced the pressure switch. The other pump still acts up. WHenever there is a drain on the water system (shower, toilet, sink, etc.) the pump pressure drops suddenly and charges back up just to drop suddenly until the other pump kicks on and puts everything right again.

    Here's my setup.

    I have two water tanks. Each tank connected to the other through an equalizing pipe. Off this pipe, two pipes provide the supply for the each pump. On the supply line, there is a gate valve and then a check valve. Coming off the pump, I have a T fitting. One way is a large plastic hose (1 in or 1 1/2) that feeds to the pressure tank and the other leads to a check vavle and then the rest of the boat.

    What I've done so far...

    The other day, a coworker added air to the tank and it stopped the behavior for two days. But it's back and just as bad. 40 PSI is high, down to 20, then back 40. Repeat till the other pump puts up 40 PSI. I've replaced the check valve off the water tank side. I checked the tank for air leaks but can detect none. Not even off the air nozzle. I don't have an air pressure gauge, so I can't tell how much air is in there now.

    Does someone have an idea on where to proceed with this? Any help would be greatly appreciated.

    Last edited by lawrencetj; 04-04-2008 at 10:56 PM.

  2. #2
    Moderator valveman's Avatar
    Join Date
    Mar 2006
    Lubbock, Texas


    It sounds like you just have the check valve in the wrong place. It should be pump, check valve, then tee to pressure tank and usage line.

  3. #3


    That's the way it's always been. It's still got the 20 layers of paint over it.

    But seriously, that's the way it's been designed and implemented on all our boats . Was working before.



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