The 22ml heating circuit pipes get hot as well as few rads before the boiler sounds like a kettle about to boil noise and then thermistor kicks in and cuts out until a few minutes when cool water circulates then it starts again but even with central heating on summer setting the boiler has a same problem with hot water at the tap could it still be the pump??

dee, June 2007

its poss the pump is faulty. it sounds like the pump is running but may be worn and not circulating the water as quick as it should.
on the side of the pump is a switch with three speed try upping it a speed.


also as mentioned try a descaler kettling is due to cold droplets of water dropping on to a hot heat exchanger.


i always use the sentinel x200 boiler noise reducer, put it into system and leave it it doesn't have to be drained out and you can still add an inhibitor.
try this site tell you all you need to know.


http://www.sentinel-solutions.net/en/


plus not knowing how old your system is or what boiler you have.

hi-spec plumbing, June 2007

Boiler is kettling. You need a descale. Fernox do a kit that allows youi to inject direct into a rad bleed screw hole. After descale you need a very good flush, then dose the system with an inhibitor.

John Sunderland, June 2007