Hi. I have a Vokera Linea 726 which drips constantly to the outside but much moreso when the central heating is on (so much that it is like a steady stream). Checking the pressure in the system while the CH is on reports about 2.5 bar. The pressure relief is set to lift at 3bar (instructions say).
I have read previous questions/answers and think that problem could be either the pressure relief valve or the expansion vessel. I am leaning towards the relief valve due to the constant dripping. (This even occurs when system is set to 1bar).
Does anyone have any thoughts on this and should it involve a professional callout? Thanks for any advice.

Martyn Thompson, March 2007

Thanks for the answer. Got a professional on the job and he says it looks like the system is full of sludge (and showed us some evidence too). Going to get some de-sludger tomorrow and give it a few weeks to clean it around.
Thanks for the advice anyway.

Martyn Thompson, March 2007

prv may have grit in it, sometimes they activate and shut again or they keep leaking. if your pressure gauge is set to 1bar when ch off and then rises to 3bar when ch on you may need to get your expansion vessel checked it may need recharging. which will keep activating your prv, so i would get the vessel checked first then prv. you can check vessel yourself if you have a trye pressure gauge.

hi-spec plumbing, March 2007