How to Remove Air from Fresh Water Lines

[Bonito38]

I have recently purchased a yacht that had been sitting on a mooring without use for nearly 4 years. Amongst several items that failed to work through lack of use were the water taps. After replacing the non-functioning water pump with a new Shurflo pump, all that came out was a small trickle of water that quickly dried up. Then nothing but what sounds like air bubbles.
I can only assume that the lines are full of air that is stopping the water coming through. How can these air bubbles be removed or bled out of the lines so I can pump water again?

[rslifkin]

The issue is likely before the pump. Air in the lines after the pump will just push through, but if the pump is sucking air, then you'll have issues.

[pcmm]

Originally Posted by Bonito38

I have recently purchased a yacht that had been sitting on a mooring without use for nearly 4 years. Amongst several items that failed to work through lack of use were the water taps. After replacing the non-functioning water pump with a new Shurflo pump, all that came out was a small trickle of water that quickly dried up. Then nothing but what sounds like air bubbles.
I can only assume that the lines are full of air that is stopping the water coming through. How can these air bubbles be removed or bled out of the lines so I can pump water again?

Make sure that there is water coming from the tank (valve not stuck closed or the outlet blocked) then check the hose to the pump, Check the filter that is before the pump (you should have one) If you have no filter, you might have some junk stuck in the pump which will likely require disassembly.

Air after the pump is easy, just open all the taps and let the pump flow until the air stops spurting out.

[Snallygaster]

Will the system pressurize at all? Might check the relief valve on the water heater if you have one. Make sure it’s closed.

[bobfromcanada]

I have the same issue after winter decommissioning/storage and anytime I'm silly enough to let the water tank run dry before re-filling the tank. You are getting an air-lock in the pump and it can't build enough pressure to just pump the water through to a tap. My solution was to install an inexpensive tap valve just after the pump outlet. I connected about 3' of hose to the tap so the output can be directed to a bucket or the bilge. You open the valve and get a whole bunch of spitting and spurts until the pump gets water and passes the trapped air. Sometimes it takes two or three tries. Then all is well until I run the tank dry again.

[twig]

On mine sometimes I have to pump the hand pump at sink to get a flow of water and then everything starts working fine.

[vanderd]

I’ve never had that issue, but have you checked the tank vent? The pump might not function if the screen on the vent is clogged with spiders or other insects.

[jen1722terry]

Wow, Twig!

We never thought of using the hand pump to purge air. Great tip.

And do enjoy the sailing season

[Cheechako]

I agree, it must be between the tank and pump. Air or blocked. Is there a shut off valve on the tank?

[SV__Grace]

Need to know if the pump stays on or shuts off.

When there's air in the system the pump will stay on and you need to bleed the air from the system (let me know if you have questions about how to do that).

If the pump is off, there is most likely a clogged hose.

[a64pilot]

I’d say there is an air leak between the hose and tank, cracked fitting or similar. Fresh water pumps will self prime, they won’t get an air lock

[OS2Dude]

With things that old I'd likely replace the hoses (Fill, Vent & Supply) and scrub the tanks. If the tanks are higher than the pump, disconnect the hose at the pump until water flows, then reconnect. If they are not, then open the faucets, turn on the pump and put your dock hose into the fill and try to get the water level to rise into the fill line. That should push the air out. Another option is to get a dock hose adapter and run water from the dock hose thru the hose leading to the pump back into the tank.

[Cheechako]

Originally Posted by a64pilot

I’d say there is an air leak between the hose and tank, cracked fitting or similar. Fresh water pumps will self prime, they won’t get an air lock

Yes, the only other possibility is that the pump is located such that it is in a high location compared with the tank and hose routing, full of air, and it can't clear the air to pump.

[doublewide]

You have air in the water pipes. As above noted, if the air is between pump and taps, just open the nearest tap and let the pump push the air, mixed with water, out. Let it run until you get a solid stream of water - waste a lot; the air bubbles may be intermittent - and then shut that tap and open the next nearest tap, and then the next, and so forth until the whole system is purged of air. Be sure to run each tap on both the hot and cold settings.

Be sure you get your hot water heater tank filled/purged of air. Don't turn on the hot water tank heating coil until the tank is full of water or you will burn out your coil in minutes.

My Shurflo pump is not self-priming, and yours probably isn't either. So if the air is between the tank and pump, the pump probably won't suck water from the tank. In that case, disconnect the line at the tank and hook it to an elevated bucket or at least an elevated funnel and introduce water, under gravity pressure, to fill the line from tank to pump (prime the pump), with the pump running, until you start getting water out of the nearest tap. Then reconnect the line to the tank and purge the system as in the first paragraph. Q.E.D.

[Scorpius]

As has been previously said, fresh water pumps are normally self-priming. I have two water tanks down in the depths of the box keel, four feet below the water pump inlet and the sure-flow pump self-primes from them no problem - as long as a tap is open so the air has somewhere to go.

I'd say that if the pump runs continuously until you shut the breaker off, and assuming your tank has water in it, you have an air leak into the system somewhere between the tank and the pump. The o-ring seal on the strainer might very well be the problem.

The other possibility is plugged lines. Disconnect the input hose at the pump and try sucking on it some other way (personally I'd do it by mouth). If you get water the pump is probably defective. If you get air, you have a LARGE air leak (broken fitting, broken or split hose, etc.). If you can't pull anything you either have a SMALL air leak or a blockage. Check the tank for sludge (you might want to do that before sucking on the hose), blocked outlet or pick-up screen, plugged hose or filter, etc.

After it's been sitting unused so long, for health reasons, you might consider just thoroughly cleaning the tank(s), and replacing all the hoses, fittings, the strainer, etc. with new ones.

Good luck! Welcome to the wonderful (and frustrating!) world of boat maintenance!