Pressure at 3bar and now suddenly nothing at all

[sam123]

I have a Valliant boiler. Whilst the Central Heating was on it was working at 3bar. It was like this for a few weeks.

Now the pressure has completely disappeared (i.e below zero), whole boiler has now shut down (no hot water or heating), and doesn't refire

I have called out an engineer but after reading other posts I fear something major may have happened, and that it will be very expensive to sort out.

 

[ollski]

I should guess that at 3 bar it blew the pressure relief valve and hence you lost all your water...the boiler won't fire because you have no pressure in there. I would keep the engineer appointment though, you need to know why you got up to 3 bar

 

[cmyers_uk]

This happened to me and was very easy to fix. The operating over three bar was because the pressure vessel diaphram had broken. I ound this out by trying to take the pressure using a car tyre pressure gauge water came out. This was replaced by myself for £35. The PSV value that blew cost £6.50 approx. Both were brought from http://www.mjtcontrols.co.uk/ you can select by boiler type etc. The manual that came with the boiler expalined what to do and an hour later I have a working boiler that holds its pressure at 1bar and only goes up to say 1.5bar when running.

I had never done this before but it was very easy