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potterton prima makes loud banging after 3 mins of operation?

as above
james kelly, November 2009
Probably a faulty pump making the boiler overheat - it should then trip out.
Or running on heating only, all thermostatic valves shut down
Or corroded flue will make it 'hunt'
Or scaled up heat exchanger
But most likely 1

Mattyb, November 2009
link Click here to see other fixes for Potterton Prima.