Air in Fresh Water Line/pump?

[stcohen]

Hi everyone,
1st post here, so please bear with me.. I have a 34' Silverton covertable that has a fresh water problem. When I leave the boat sit for more than a few days, the fresh water pump runs without pumping water. I have to open up one side of the pump and hold my hand over it before it begins to pump again. I have added water to the tank prior to doing this, but I am sure I am not adding more than a few gallons each time I do this. Adding water alone does not do the trick. I need to remove the water line from the delivery side (not supply side) hold my hand over the open side of the pump, and away it goes. I don't think the tank is empty, the hot water tank is a new 11 gallon, I am not sure where the fresh water tank is. Should I turn on the water prior to the pump? Is there anything else I could try? By the way the water pump looks like it was recently replaced. We have owned the boat for a few months.

Thank you for any advice!!!

 

[SpinnerBait_Nut]

Re: Air in Fresh Water Line/pump?

I'm not up on these kinds of boats but I would think you would need to turn water on prior to turning pump on.

 

[stcohen]

Re: Air in Fresh Water Line/pump?

We have an rv with a similiar fresh water pump, it doesn't matter which one you turn on first. I wonder if it is any different on a boat.. Thanks for the advice!!

 

[SpinnerBait_Nut]

Re: Air in Fresh Water Line/pump?

My fresh water pump for my RV works if there is water.
I have turned it on by mistake in the dark without any water in the tank but have not had any air locks or anything like that once I put water in the tank.

 

[Silvertip]

Re: Air in Fresh Water Line/pump?

You should not have to do both -- but the pump may need priming which is what you are doing (or helping to occur). The pump is intended to be left on so the water system is pressurized. When the system is pressurized the pressure switch in the pump turns the pump off. When you open a fixture, water flows until the system pressure drops to the "turn on" pressure at which time the pump again runs until the system reaches the "cut off" pressure. When a fixture is open it is not uncommon for the pump to run continuously or to pulse on and off. It all depends on the size of the accummulator tank (not the water tank) if it has one. Obviously if there is a drippy fixture or a leak in the system the pump will cycle. When the boat is docked for a time the switch can be turned off to kill the system. But once the system is primed you do not need to turn the pump on with the switch each time you want water. Turn it on and leave it on. The only time this info would be invalid is if the water system is very basic such as having a pump that is simply a pump and has no cut-in/cut-out function. I don't think that's what you have since you have a water heater. Even the cheapest RVs have pressure systems. Go here for a diagram and description of how an RV system works. A marine system is similar.

ccis.com/home/mnemeth/plumbing/plumb.htm

 

[tashasdaddy]

Re: Air in Fresh Water Line/pump?

you may have a slight air leak causing the pump to loose prime. does it have a check valve? between pump and tank.

 

[stcohen]

Re: Air in Fresh Water Line/pump?

Hi,
Thanks for the advice, I don't think I have a valve between the tank and the pump. I am not really sure where the tank is located. I ko I don not have an accummulator tank. h com back to the oat after a few days, we turn on the pump, and open a faucet.The water usually runs for a second or two, then the faucet runs dry, and the pump runs continuously. I then have to prime it before the water works agin.. I agree that I am priming the system, maybe if I leave the pump on this will fix the problem. Do you think I should replace the pump?
Thanks again for all of your help!!!

 

[tashasdaddy]

Re: Air in Fresh Water Line/pump?

the system should be sealed, you have a leak somewhere, allowing the pressure to drop and the pump loose it's prime.

 

[stcohen]

Re: Air in Fresh Water Line/pump?

By turning the pump off, wouldn't that casue the loss of preassure? When I leave the pump on, it reaches it's cutoff point and stays off until I turn the water back on. Only seems to happen when I turn the pump off for a few days.