Baxi 105he Instant pressure loss

[corgiman]

No its isnt.

the PRV would open at 3 bar and this points to the expansion vessel.

sounds like you have small leak on the system somewhere.

try injecting some fernox leak sealer into it. its so small it may work

 

[Brompton]

Put fernox leak sealer in a while back. Tested CH system for leaks using Jason Vaughan advice on similar forum topic. Test showed pressure decrease within boiler, not in isolated CH system. Pressure vessel showed no charge at time, so pumped up to 1.0 bar. Haven't checked yet if pressure still holding in it. Any other tests I should do? Appreciate your help

 

[corgiman]

I would have said that the exp vess was ok as the pressure is not rising up during operation

Also the PRV is not dripping.

So the pressure loss is not being caused by either of these.

there must be a really really small leak somewhere, IMHO it would be worth whacking some more leak sealant in and see what happens

 

[Brompton]

Thanks Corgiman. Will give it a go.

Out of interest, should the pressure dip by 0.5 bar when the HW comes on, and go back up when the HW overrun ends?

 

[corgiman]

the pump running will cause the guage to fluctuate especially in HW as the pressure created by the pump is higher