Vaillant expansion vessel playing up

[gassafe]

Hello,

Just got back from a Vaillant ecotec combi, the customer has had pressure up in the red and water running from safety pipe.

First check was the expansion vessel, with boiler at 1.2 bar the vessel had no air or water coming out when pressed.

I depressurised the boiler and checked schrader valve again, still nothing so i pump it up to 0.75 bar recommended pre charge... As soon as i removed the pump it started to blow all the pressure out of the schrader valve... after blowing out all pressure it started to suck in??? this was proved by putting my manometer on it and almost losing all my liquid in it!!!!

Is it poss to buy just the Zilmet schrader valve? I put a different one in from a car type valve the customer had and it holds better but is passing a tiny tiny bit, i put the plastic seal cap on so it may hold for awhile, the schrader valve was slightly different tho.

The customer is keen to replace just the valve because it seems silly to replace the whole vessel ( money wise ) Can a replacement Zilmet valve be purchased?? I have never seen this fault before, Probs just fitted new vessels... is anyone replacing schrader valves to solve these issues or do you all just change vessels?

 

[GrahamM]

Dont recall any Vaillant expansion vessels in particular, but I have replaced the schrader in loads of others. Is it not the bog standard valve that is in it? For example: Halfords | Halfords Valve Cores - Schrader

 

[gassafe]

Thanks for the link, It looked like that only slightly smaller i believe. I think I will start removing them from boiler rip outs with vessels etc, these little bits come in handy sometime! Like rad pins, i remove them too now... =]

 

[GrahamM]

If they look like that then this will be them. As far as I am aware they only come in one size. These are used from cars, to airplane tyres to pressurised air guns. If you know any tyre fitters get a handful from them. I would not reuse old ones as it is only a very thin bit of rubber that creates the seal and easily wears.