my Ravenheat 820/20 combi keeps overheating?

http://www.youtube.com/watch?v=KeO2gswQQe4

Q
December 2013

Change the expansion vessel rather than top it up. It's a pig of a job if it's located behind the boiler and you can expect to pay up to and around the £250 mark depending on where you are and the location of the boiler. If it's still not working after that then it may be down to muck in the system blocking the manifold in the boiler in which case another part is required and I'd suggest a clean out of the system either by powerflushing or fitting a magnetic filter or both.

Gas Safe Engineer in West Yorkshire
November 2013