Help - Central Heating Leak

[Charlie69]

I have a Worcester 28CDI boiler.

The pressure keeps dropping from 0.5 bar to 0.2 bar after the CH has been on for 3 hours. Whilst the CH is on the pressure rises to 2 bar.

The boiler has been serviced by worcester and have been told the fault is definately not with the boiler.

I have attached tissue paper to each radiator valve and no water leaks have been identified.

I added the Plumb sealer from B&Q on Wednesday evening (PlumbSure Central Heating Leak Sealer Concentrate) through a radiator. This if anything has made the water pressure drop more quickly.

Should I now try Fernox F4 leak sealer or will this cause more problems?

Your help / advice would be very much appreciated.

 

[kidgreen61]

The pressure keeps dropping from 0.5 bar to 0.2 bar after the CH has been on for 3 hours. Whilst the CH is on the pressure rises to 2 bar.

That sentence doesn't make any sense!

However, it sounds as though you have an issue with your expansion vessel.

look at the FAQs on this site for an answer

 

[Charlie69]

sorry i'm a complete novice.

CH turned off = 0.5 bar
CH turned on = rises to 2 bar
CH turned off = 0.2 bar

Pressure dropped by 0.3 bar!

 

[mcmoby69]

if you had the same problem before the service, get worcester back. you paid for it and they havent done it right. how much did they charge you for the service?

i agree it sounds like an EV problem.

 

[Charlie69]

Thank you for the replies.

If the problem is with the EV, where's all the water going?

I have placed a plastic bag over the overflo tap on the external wall and it is empty!

 

[Burnerman]

There aren't any water leaks that we are aware of....yet!
With the system depressurised (i.e pressure gauge reading zero) the expansion vessel should be pressurised with air up to around 10 psi, using a car tyre foot pump or similar.
The water filling loop is then opened and the system pressurised to 1 bar, or whatever the manufacturers recommend.
Once thats done, the pressure should be stable with the heating off, and rise to around 1.2 bar or thereabouts when its on.
When checking the air in the E.V, if water should squirt out through the valve then its gone AWOL, I'm afraid.
John