Worcester 28CDI leaking expansion vessel pressure valve

[ABN]

Hi

I'm losing pressure in the expansion vessel. Have confirmed that the tyre like valve has a slow leak.

Is the insert the same as a normal car tyre valve? If so can I just pop down to my local garage to get a new valve and valve removal tool and is there anything I should be aware of when replacing?

If not where to get one and how to replace?

Thanks

 

[nickso]

You can get the schraeder valve core and a tool to remove it. Good luck on the cdi though as they are often inaccessible.....check before you buy anything.

 

[ABN]

Access on this model is easy thankfully.

Will google "schraeder valve core" to see where to get one. Thanks.

 

[MANDATE]

Halfords!

 

[ABN]

Halfords!

So just a normal tyre valve then

 

[ianmcd]

yes just a normal tyre insert its called a schraeder valve and Halfords will sell you a tool with spare valves I think about £4 and has 3 or 4 valves in it

 

[Agile]

They rarely leak. It could be loose and just need tightening?

In any case the cap will usually hold in the presure.

Tony

 

[Madrab]

If you have been losing pressure from the Expansion Vessel (EV) and are going to replace the schreader type valve you need to release the pressure from CH circuit and EV prior to removing the valve. Once replaced, the expansion vessel must be pre-charged on your system to min 0.5Mbar or at least proportional to the static head pressure prior to the system being used again, check with the MI. This is usually performed using a hand pump with a pressure guage. Have a rad bleed valve open slightly to let the displaced water from the EV escape whilst pumping up to the correct pressure to avoid prematurely pressurising the CH circuit. Once the vessel is charged correctly, re-pressurise the CH circuit through the filler loop.

 

[MANDATE]

0.5 Mbar ? more like 0.8bar to 1bar wouldn't you say?

 

[Madrab]

Oops, did I say Mbar, apologies for the typo. Thanks for that spot Mandate.

The spec for the EV on that boiler calls for 0.5 bar per 5m (17ft) of static head, that's what it ships with, though as you say a bit higher wouldn't cause an issue.

 

[Agile]

I dont agree with that pressure.

About 60% of the intended system pressure!

So about 0.9 Bar if to be set at 1.5 Bar.

Tony

 

[Madrab]

I dont agree with that pressure.

About 60% of the intended system pressure!

So about 0.9 Bar if to be set at 1.5 Bar.

Tony

Fair enough Tony as agreed with mandate - Was quoting the MI base spec for that boiler's EV.

 

[ABN]

Went to halfrauds and got a tool and some valves.

Using the tool found the valve was a bit loose so tightened it. It still leaked a little so thought would put new valve in anyway.

Pic shows old valve on the left and new valve on the right. Of cause new valve don’t work.

Refitting the valve, after giving it a good blow, seems from my balloon test that it may have stopped the leaking. (Balloon test finger of a surgical glove over the valve held in place be rubber grommets and see if it inflates)


Maybe should have got the short version although that looks different as well. Still would like to get a new valve just in case but a little confuse as to exactly what valve I should be buying.

 

[Agile]

They rarely leak. It could be loose and just need tightening?

Tony

Using the tool found the valve was a bit loose so tightened it. It still leaked a little so thought would put new valve in anyway.

Refitting the valve, after giving it a good blow, seems from my balloon test that it may have stopped the leaking. (Balloon test finger of a surgical glove over the valve held in place be rubber grommets and see if it inflates)

I just put a little saliva over the end of the valves too see if they blow bubbles! Learnt that from my Father on his cars.

Tony

 

[ABN]

Never had any luck with that method for very small leaks hence the balloon method and lots of time.