Monza heatline hot water issue

[Pturner]

Good evening ,
Heatline monza, pressure gauge rises and reacts as if air hitting the exchanger, boiler cuts out then back on it then opens the prv. This only happens when there is a demand for hot water. Heating seems to run smoothly with minimal increase in pressure. I checked expansion vessel and this was fine. Is it possible dhw plate exchanger partially blocked

 

[Davefal]

Good evening ,
Heatline monza, pressure gauge rises and reacts as if air hitting the exchanger, boiler cuts out then back on it then opens the prv. This only happens when there is a demand for hot water. Heating seems to run smoothly with minimal increase in pressure. I checked expansion vessel and this was fine. Is it possible dhw plate exchanger partially blocked

Have you checked the 2filters

 

[Davefal]

Have you checked the 2filters

Is the p to p heat exchanger getting hot