No pressure at red expansion tank

[biggjedd]

Hello could someone please help??

I noticed the guage on the small red metal tank in my attic which is part of my central heating system was at zero. In the past ive opened up the two black taps on the metal hose and the tank has filled up and guage goes up and stays. Unfortunately when i do this the needle on the guage rises but as soon as i close the black taps on the hose it goes all the way to zero quickly.

Could someone explain whats wrong and is it damaging the system and what i should do about it to fix it?

Many thanks in advance..

 

[oldplumber]

sounds like your expantion vessel is the red tank and that it may have failed causing your prv to leak and cause a pressure drop. best to call in am engineer to check out your system and carry out any repairs needed. i would expect your boiler to cease to work if the pressure on your system has dropped off.

 

[biggjedd]

Thanks for your quick reply. What's the "prv"? Im not aware of any leaks amd the boiler seems to be working.. Is there anything i can do as cash for an engineer's a bit tight at the moment? Also does this sound like an unsealed or sealed system? Thanks again..

 

[oldplumber]

pressure relief valve

 

[Gray0689]

Sealed system

 

[Dotty]

if you look at your red tank (expansion vessel) you'll see another wee valve with 3 bar on it, this is your pressure relief valve (PRV). it should have a pipe poking through the wall, go outside, look for the end of that pipe and see if there's water coming from it.

let us know what you find!

 

[biggjedd]

Thanks to everyone for replying, it's much appreciated..

Yes, I checked the red expansion tank and saw the black 3 bar prv on top and pipe leading away to outside. I then filled the tank to just under 2 and ran outside.. there was no water coming out the pipe from the prv. By the time I got back to the tank it was back down to zero again.. The pressure goes down immediately.. does that mean the water is going down the remaining pipe to the system? Thanks again..

 

[oldplumber]

means you expn vessel is probably us and needs replacing, easy as its accessable and youll probably need a new prv, get out an engineer to do it right and show you how to set up the sysem as 2bar is to high, normally around 1bar

 

[Bartdude]

What hot water system and boiler do you have?

 

[biggjedd]

Hi it's a Suprima boiler and its a sealed system..