Central Heating Problem

[andyredtyke]

Any advise gratefully accepted

I have a Myson Apollo boiler, a Wilo Gold 50 pump, Honeywell mid position valve and Danfoss timer, recently i had to change the Honeywell valve and ever since when the heating turns off when up to temp on the room stat there is an almighty water rushing sound through the pipes and they bang and rattle. The radiators upstairs get warm but a couple downstairs are only aired and not as hot as upstairs.

I have bled the radiators, adjusted the settings on the pump but still get this problem every time just on the central heating.

Any ideas ??????

 

[ChrisR]

WHen the heating stops the pump should keep running to cool the boiler, otherwise things overheat and boil.
It's controlled by an Overrun Thermostat inside the boiler. Yours may be bust!

Circulation problems are either due to a blockage such as sludge which is basically rust from radiators, or a pump not being effective due to age or a blockage inside it. If you CLOSE all the "good" rads, do the poor ones get hot? If not, they're blocked.

 

[andyredtyke]

Hi Chris

thanks for reply, looking at what you have said, i've noticed as soon as the heating turns off the pump does stop running so could be this overrun thermostat, i'll replace and see what happens.

Many Thanks