Vokera pressure rising

[ejt70]

Hi,

Pressure has been rising to 3 bar and prv opening over past couple of weeks on Vokera syntesi combi. Had similar problem last year. 3 separate engineers called out - first replaced prv, no cure, came back out, didn't know what else to do. Second replaced plate heat exchanger, water was hotter but pressure kept rising and prv opening. Third was Vokera engineer who replaced expansion vessel. System fine after this until now with same problem. Will membrane have gone already? Any ideas much appreciated.

 

[vulcancontinental]

Possibly needs repressurizing. The Vokera repair is warrantied a year anyway, not the whole boiler but the changed component.

 

[McCombi]

Not sure if these have similar expansion vessel hoses that connects vessel to boiler?
Could be that that's choked.
Could be inadequate bypass and when demand satisfied there's nowhere for pump over run to get rid of excess heat and it's causing pressure rise an Prv to open?

Not too familiar with this model but worth getting them checked.