worcester 240 no heat in return for rads

[david11]

Hi Im having problems with the central heating side of my worcester 240 combi boiler . I've just fitted a new expansion tank as the pressure was droping this has fixed that problem and the boiler is holding presure fine but now i cant get the radiators to heat . There is heat going to the flow fine but is'nt coming out the return side or the rads on the upstairs rads. The down stairs are stone cold ive tried draining out and refilling not making any difference .the boiler has the micro bore pipe work on the rads could they be blocked on the return or is there a valve that has maybe got closed or busted both the big return and flow are fine at the bottom of the boiler both open
Thanks and any hel[p would be much appreciated Dave

 

[jack_d]

Is it just the return pipes that are stone cold or the whole rad's? If the rad is cold but the flow pipe is hot then check your TRV pins.

 

[david11]

Is it just the return pipes that are stone cold or the whole rad's? If the rad is cold but the flow pipe is hot then check your TRV pins.

Thanks for the reply I've tried the pins they all seem fine the rads are heating up a bit but the return is very slow and luke warm to the touch at the boiler .the upstair rads are hot the return on these is'nt even great but better than the down stairs there is presure on all the returns when i opened up the rads with the flow closed of not sure if its a blockage or a dodgy valve somewhere
Cheers dave

 

[freelander100]

is the hot water ok. the divertor valve rear section could be stuck in hw mode. have you bled all the air out, there are no filters in the 240 boiler on flow or return pipes. check the gas to water heat ex for a blockage, if it worked b4 you changed vessel then dont think that could be it.

 

[david11]

Thanks the hot waters fine checked for block not that the rads are now hot seems to be working its way through but very slow must be gunked up i think put in some cleaner dont no what to try next a complete high pressure flush maybe last resort
Thanks Dave

 

[wetneck]

You only fit a new xpansion tank if the pressure increases, if it was dropping,then it would be the PRV or youve got a leak somewhere. Possibly now caused a blockage somewhere in the system.