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Air in the water system after driving


sreve

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Hi all

I've got a strange thing going on at the moment,we are away travelling right now and after a few miles driving when we stop and use the kitchen tap (I think it's only on the cold water side of the mixer tap) only air comes out for a few seconds and then the water explodes out.Once this has happened then the tap works completely normally but then after a drive the airlock develops again.It doesn't matter how much water is in the tank.It only seems to be happening with the kitchen tap.

Any help or advice appreciated.

 

 

 

 

 

 

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OK Thanks for the extra info.

 

It sounds like you may have an air leak on the tank side of the pump so a couple of things to check. First remove and inspect the clear plastic grit strainer on the inlet side of the pump. Second remove and clean the non-return valve again on the inlet side of the pump.

 

Finally check very carefully for leaks around the pump and pipework when pressurised. A few years ago I did not drain the pump sufficiently well and the casing cracked during a severe freeze. The leak was only visible by wiping with a piece of blue paper towel but caused symptoms not too dissimilar to yours.

 

Do you get air in the system if you leave for say 24 hours, or is it definitely only after driving?

 

Keith.

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The symptoms indicate that the problem almost certainly lies ‘upstream’ of the water-pump, between the water pick-up-point in the fresh-water tank and the pump’s inlet.

 

If (as Keith mentioned) Auto-Trail has fitted a separate non-return valve (NRV) in the hose leading from the pick-up-point to the pump, check that the valve is functioning correctly by disconnecting the hose from the pump and blowing down it to confirm that the valve closes completely.

 

If the NRV fails to close and the motorhome has an external fresh-water tank that’s some distance below the pump, there’s a good chance that the vibration produced when the motorhome is driven will provoke the water in the feed-hose to siphon back into the tank, particularly if there’s not a great deal of water in the tank to begin with. If the water does siphon back and the feed-hose fills with air, the likelihood is that it will be the cold-tap closest to the pump where the fault shows up.

 

If there were an actual leak in the water-feed-to-the-pump assembly - a crack in the pump’s strainer, or in the NRV, or the hose connections not being air-tight - I’d expect this to result in some spluttering at the taps as air as well as water is sucked in by the pump.

 

(Given the motorhome’s age, if there’s any doubt about the NRV’s opreration, it would be best to replace the NRV.)

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Thanks again for the replies

There was some muck in the grit strainer next to the pump but not much so I cleaned it out,I checked the non return valve between the tank and pump this was working well,I also took the kitchen tap apart and re-assembled it(the brass nut on top seemed only hand tight) so maybe air was getting in there.I couldn't see any leaks or drips anywhere else.

We won't be on the road for a week so won't be able to test it until then but keep any thoughts coming.

Simon

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