Boiler temperature dropping them cutting off

[Sanjay Savani]

I have a BIASI M90E32S which had a faulty expansion vessel. Pressure kept dropping so we added a new external vessel. But now the heating comes on for an hour or so. At a certain temperature the boiler cuts off. After a restart it works for an hour again. Please help. Could it be a faulty pump or something else? Did the existing vessel need to be isolated? Because it isn't right now.

 

[Last Plumber]

I have a BIASI M90E32S which had a faulty expansion vessel. Pressure kept dropping so we added a new external vessel. But now the heating comes on for an hour or so. At a certain temperature the boiler cuts off. After a restart it works for an hour again. Please help. Could it be a faulty pump or something else? Did the existing vessel need to be isolated? Because it isn't right now.

Why was the pressure dropping?
When you say it cuts off, do you mean it needs resetting?

It sounds like you need a Heating Engineer.