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Crusair Waterpump or ?

Discussion in 'HVAC' started by Marblehead01945, May 21, 2012.

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  1. Marblehead01945, May 21, 2012
    #1
    Marblehead01945

    Marblehead01945 Member

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    We put the boat in the water this past week (Eastbay 55) and the AC doesn't seem to work. The yard took the raw water pump out and it worked fine on the bench but doesn't seem to want to prime itself (its slightly up hill but worked fine last season) and work once its on the boat. The check valve was tested as well and yes the seacock was opened. Has anyone run into anything like this?

    Regards to the list!
  2. Pascal, May 21, 2012
    #2
    Pascal

    Pascal Senior Member

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    Check valve??? Where?

    I ve never heard of pulling the pump and bench testing it... You can't bench test it because you need to test it in place with the water inlet. Of course it s a nice way to bill a couple of hours of labor...

    Either it runs or it doesnt. If it doesnt and if there is power to the pump then yes you pull it for repair... Otherwise you work on the priming issue

    AC pumps are not self priming and ...
    1)- must be below water line
    2)- must be fed by an uphill hose with no high or low points

    As simple as nr 2 is, many builders manage to mess that one leaving the owner with regular priming issues

    First thing to check is that there is no restriction in the line between the thruhull, strainer and pump inlet. I ve sen garbage bags stuck in the pick up... Loose shells in the hose... Masking tape Left over the pick up... Etc...

    First thing i check is the strainer then leave it open and open the seacock to make sure there enough water coming in. If that is ok, then pull the hose off the pump inlet and open the seacock. Depending on location you may want to out a bucket under the hose to catch the water...

    If the pump is installed correctly, nr 2 above, it should self prime. If not, then you will need to bite the bullet and install it correctly. As a bandaid you can hook up a hose in the pump discharge to prime it

    I ve also seen worn out / corroded impellers on these cruisair pumps. If so, I d recommend switching to a March pump with the magnetic drive. They last a lot longer

    But again, that check valve is a big red flag... Where is it in the system?
  3. Capt J, May 21, 2012
    #3
    Capt J

    Capt J Senior Member

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    In Addition to what Pascal said, I'd open the seacock with the hose off of the pump and make sure the hose flows a good amount of sea water. Second, I'd make sure there are no air leaks on all of the hoses and plumbing to the pump, 3rd I'd make sure the cover plate for the pump isn't corroded through, the shaft seal, and then check the impellor.
  4. Bill106, May 22, 2012
    #4
    Bill106

    Bill106 Senior Member

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    The "standard" in-line check valve is definitely a red flag item especially if it's on the suction side of the pump. Even the self-priming Oberdorfer pumps don't have the capability of opening a stock check valve there and on the outlet will lose quite a bit of head pressure at the condensor.

    If the installation absolutely requires one, a swing check valve can be used but it will most likely require bi-annual maintenance for cleaning the debris that will accumulate on the seal face and prevent it from sealing and doing it's job so it should be installed with easy to remove couplings.
  5. Marblehead01945, May 22, 2012
    #5
    Marblehead01945

    Marblehead01945 Member

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    Thanks all for the advice. I'm hoping the yard will come down and fix it this week as I research the issue with everyone here. I've attached a picture of the check valve and pump. The pump appears to be below the waterline but its close for sure. I'll let everyone know what the solution was once I get it sorted. It seems simple enough but its a boat right?

    Attached Files:

  6. Capt J, May 22, 2012
    #6
    Capt J

    Capt J Senior Member

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    Take the hose off of the pump and see if the hose flows water at that height. If it does, yank the check valve out of the system as there is no need for it........
  7. Marblehead01945, May 22, 2012
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    Marblehead01945

    Marblehead01945 Member

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    Will try that. Thank you. Whats the purpose of the check valve in this configuration? Is it so all the water doesn't back out when the system is off (I guess it can't if the pump is below the waterline), does it help with the prime or is it there just to confuse everyone?
  8. Pascal, May 22, 2012
    #8
    Pascal

    Pascal Senior Member

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    This check valve is the most stupid thing I ve seen in a while! There is no way the pump will self prime!

    I just hope they didn't put it in because the pump is above water line... And I can't believe the yard remove the pump to bench test while ignoring the check valve!


    Not sure have the oil change pump deep in the bilge under the check valve and close to the strainer is very smart idea either...
  9. Marblehead01945, May 22, 2012
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    Marblehead01945

    Marblehead01945 Member

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    They said they "checked" the check valve first and said it was "okay". This will definitely be continued. I just wonder if the pump is ever so slightly above the waterline. Its just so close I really can't tell without taking off that hose (which they will do when they come back to "fix it".
  10. Pascal, May 22, 2012
    #10
    Pascal

    Pascal Senior Member

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    First thing to do is pull the hose off the pump inlet and see if water is coming out and determine one where it sits in relation to the water line. It s something you need to know as owner/operator!!!
  11. Marblehead01945, May 22, 2012
    #11
    Marblehead01945

    Marblehead01945 Member

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    I agree with you, its just one of those things thats always worked fine and I don't usually take things apart if its working unless its maintenance related. The inlet to the pump isn't really on my list of things to maintain per se (except checking the hose and fittings) however now of course it becomes vital to knowing whats wrong with this system. So.....to be continued......
  12. Pascal, May 22, 2012
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    Pascal

    Pascal Senior Member

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    I understand but it s also a safety issue. It s good to know what is below waterline, what can leak, and what can not. A lot easier to find out while things are dry and brightly lit :)

    BTW I hope that check valve is bronze and not brass... Brass can corrode and fail is a little as a couple of years when used in salt water
  13. Capt Bill11, May 22, 2012
    #13
    Capt Bill11

    Capt Bill11 Senior Member

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    No need to pull the hose off, just open the plastic bleeder plug on the wetted end. Then replace the plug with a valve so you can prime it easily in the future.

    And while you are at it remove the check valve. And either **** can it or if you find you really need it at least put it on the discharge side of the pump where it might do some good.

    If the pump is bad replace it with a March A/C pump. They have a plastic impeller that is magnetically driven for long life.
  14. Bill106, May 23, 2012
    #14
    Bill106

    Bill106 Senior Member

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    That check valve has a cracking pressure much higher than that centrifugal pump could hope to draw when it's dry and probably just sufficient when primed. I have modified that type by cutting back the spring in gradual steps until I had just enough to close it when at rest but if someone in the future replaces it they will have to do the same thing all over again.

    If you need to have it, and it looks like you probably do, a far better solution is to install a swing check valve in the line instead, they rely on gravity to close a flap instead of a spring driven plunger and way less cracking pressure. You will still probably have to prime it the first time though.

    That hose used for the line is not the correct type either and should be replaced. That is vacuum hose and not rated for below waterline use, replace it with some good quality wire reinforced hose rated for suction. Black rubber hose will also grow less crud inside compared to the clear vinyl you have now.
  15. Marblehead01945, May 23, 2012
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    Marblehead01945

    Marblehead01945 Member

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    This forum is amazing....excellent source of info. Here's the latest. The yard wants to nuke the check valve and they are calling the manufacturer to find out how they feel about that. They also think that the pump can't overcome the check valve. I'll keep you posted....

    PS: Bill-they are going to speak to them about the hose as well.

    Regards to the list.
  16. Capt Bill11, May 23, 2012
    #16
    Capt Bill11

    Capt Bill11 Senior Member

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    IMO, you may want to consider using another yard. Between taking the pump out to "test" it and now wanting to ask the manufacturer about whether or not to replace the check valve, I would not have much faith in their judgment.

    Did they tell, or better yet, show you what condition the impeller was in when they bench tested it?
  17. Marblehead01945, May 23, 2012
    #17
    Marblehead01945

    Marblehead01945 Member

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    Hi Bill-The impeller was fine. The reason they need to consult the builder is because the boat is still in warranty. The yard is the authorized warranty yard and honestly they have been great with all the other minor things so I need to kind of let this sort itself out.
  18. C4ENG, May 25, 2012
    #18
    C4ENG

    C4ENG Senior Member

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    Waiting to hear why your pump would not prime.

    I can not tell you how many times I have fought with pump priming issues and just when you thought you experienced every possible way... there is just that one more way that she's not taking a prime.
  19. Marblehead01945, May 25, 2012
    #19
    Marblehead01945

    Marblehead01945 Member

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    I believe the mechanic is coming down on Tuesday to hopefully fix it. I don't know if they have heard from the manufacturer or not at this point but thats the plan. I'll let you all know as soon as I do.
  20. C4ENG, May 25, 2012
    #20
    C4ENG

    C4ENG Senior Member

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    Tuesday!?! Thats to long. I am coming down to that boat and we are going to figure this **** out right now!
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