Over flow

[ste b]

Afternoon peeps, can someone help me out,i not up to scratch on central heating yet, my mate has asked a plumber to look at his combi boiler because it is losing pressure and every time he puts on the heating he has to fill up through the filling loop to get the pressure back up so he can get hot water and heating, he says he has to do this every time he switches on, also he says water is coming out of the over flow pipe all the time, i wont be fixing it i just want to help diagnosing the problem so i can tell him if he is being ripped off, the plumber has told him at least 300 squid to repair , any advice is appreciated....

cheers......

 

[Phil]

It sounds like the expansion vessle has failed/split diaphram/needs re-charging. As the water gets hot it expands so the expansion vessle absorbs it (sealed system ), if it fails then the pressure will rise and when it gets just over 3 bar the pressure releif valve (PRV) will expell the water. When these valves go off they sometimes don't shut off properly due to dirt etc and can be cleaned or replaced.

This is why the overflow as you call it is dripping/

 

[Grumpygrouter]

I'm not a plumber but I agree with Phil. I had exactly the same problem with my Worcester Hiflow. Expansion vessel being changed cured the problem.

 

[ste b]

Cheers phil, hey no offence but what do you call the over flow,i a learner remeber,

appreciated thanx

 

[Phil]

Normally called PRV - pressure relief valve.

 

[sonray ltd]

prv's faulty.
no way is the ex vessel faulty unless the pressure is rising not just leaking.

 

[Phil]

Yes, I read it that he had to top up after heating.

 

[ste b]

is it still looking like the PRV, or you guys confused, just to confirm he says he has to top up befoe he puts the heating on,sorry if i confused anyone.

cheers