LOOSING PRESSURE ON COMBI HEATING SYSTEM

[Brunel]

Gradually losing pressure on combi. heating system. A smallish system in a flat, 7 radiators+ a couple of towel rails. No sign of any water leaks.
The boiler is a VOKERA UNICA 32HE.
Have been advised that it could possibly be the boiler expansion vessel.
If it is this, is it a relatively straight forward job to replace?
I am trying to obtain a ball park figure on cost etc.
Thanks

 

[Riley]

You won’t get a figure on here as it’s too much geographical variation. Get a couple of guys in to quote

 

[Deleted member 32524]

Probably will not need changed, most of the time. Should be an hour charge, no parts needed. If its worse then take it from there. Depending on lay out and other points regarding a direct replacement, but you could fir an external on if space available.

 

[Ric2013]

If it is the expansion vessel, the next thing you will see is water pressure rising massively when heating is on, water being ejected through the pressure relief valve dump, and then, when the system is cold, low pressure. If the above never happens, then it may not be your expansion vessel (or you have a radiator full of air somewhere).

 

[SimonG]

Tape a plaggy bag over the pressure relief outlet outside to see if you get water from it.