Water pump expansion vessel - what pressure to add air?

MrCostington

Hi, I have the pump/pressure vessel as shown below.

Pump keeps coming on on it's own. I replaced 4 valves some years ago which had no effect. It's become worse the last while so did a bit of an experiment to eliminate any leaks in pipes, I closed the stopcocks on the hot and cold outlets, still coming on.

So I read up on the pressure vessel and see it uses compressed air. Gently unscrewed the cap on top and air rushed out so assume the valve core is faulty (looks like the type in a car tyre????).

The pressure vessel is 1L capacity and rated at max 10bar, it's a Zilmet brand.

Any idea how much to pump it up by after I replace the valve core?

PS I assume I top up with the pump off and all taps etc closed?

Wearb

I don't know exactly, but you won't go too far wrong if you set it at 0.2 bar less than pump working pressure.

EDIT. Do this with pump off and valves and a connected tap open.

MrCostington

Hi thanks, I just logged in to say I wrote to the pump manufacturer after seeing their branding on the far side of the pic above. 13PSI and procedure as you outlined.

PS re watching TNG and seen a "Hew" episode the other day, assume that's him in the pic:)