Myson Apollo 30/50b

[Neil96]

I have just installed a new O/H stat on the boiler, i had issues with the pilot light cutting out after 10 - 15mins, which seemed to do the trick. After a couple of days now the boiler is getting piping hot and now over heating, the expansion tank last night was like a sauna (red hot with steam), and the boiler sounds like someone flushing a toilet ( best to describe it), pipes have started banging. I have checked the pump which seems to be working fine, plenty of water in the expansion tank, wall t/s is operating the boiler properly. Everything seems to be ok on the H/W side, it seems to be happening on the C/H. Any ideas of what it might be? Your help is appreciated.

 

[twgas]

do you have a by-pass, TRVs, 3port or 2*2port valves and how long b4 the banging starts

 

[Neil96]

I have TRV's downstairs and 2*2ports upstairs. It takes no longer than 45-1hr before the trouble starts. The boiler starts to sound like it has a large bubble inside it. The rads are very very hot also. Would Hi/Lo stats on the boiler play a part in this?

 

[twgas]

probably high stat fault, try setting switch to low and see what happens

 

[Neil96]

Thanks for responding twgas. Because there was so much hot water and heat in the expansion tank, the first thing i did was drop it to low. Problem is still the same. Someone has suggested the circuit board on the boiler? what do you think?

 

[twgas]

dont remember ever seeing a PCB on 30/50B,
could be t/stats or wiring loom to stats, might also be gas valve not shutting off properly

 

[bengasman]

check the boiler stats first of all

 

[Neil96]

Many thanks for your help guys. I'll give them a go.