unvented central heating problem??

[Tom.davenport12]

Hi guys i have an unvented cylinder and system boiler in a coach house and have good hot water but the central heating is struggling to get hot, just staying lukewarm throughout even flows and return from the boiler when fired up. It seems the boiler tries firing but doesn't get anywhere so the keeps cutting out. any ideas would be brilliant please????

 

[ShaunCorbs]

check the port valve is working
check the pump is pumping

its normally something simple if hot waters working

 

[Tom.davenport12]

Ok thank you is there any sure way of checking the pump and port valve? the pump is running but doesnt sound too powerful. i do suspect the system itself as black water when bleeding rads. could it be blocked with sludge do you think?

 

[daWilko]

Hi - I'm not a plumber (just a 'umble spark) but I think it could be blocked flow, weak pump, stuck valve or even an electrical fault. Your local friendly Gas Safe Person could diagnose and fix for you.

 

[daWilko]

Re reading your original post - if your programmer allows it, turn off HW and see if any more heat gets to the rads. Just a thought on a cold night ...

 

[Gazzzz101]

Sounds like a circulation problem, check the pump, the port valves of if pressurised check the pressure.