myson apollo 30/50b?

I a similar problem, a small clunk, then a rush of bubbles surging thru' the system and finally a massive banging noise, like someone hitting a radiator with a hammer. Pump overrun stat, goes in the back towards the bottom on the right onto a pipe coming off the heat exchanger. You need to take off the upper, outer cowelling, then the inner cover to get at it, costs about £15.00. Just unscrew old overrun stat and replace, only a few wires. Make a note of existing set-up or take a photo for reference if you really need to but it is very, very simple and obvious once you get the covers off.

DainO
November 2012

thanks for your quick reply will look into both as they are both getting on i years

marks
January 2011

you can't blow a t/c most likely cause is pump or divertor/zone valves faulty causing overheat stat to trip this disables the t/couple once they have tripped they can become tempremental

brian
January 2011