rads not getting hot - powerflush needed?

[wolvesdave]

Hi, I have a fuelsaver 100f boiler (old and inefficient, I know!) on 15 rads but recently some of them have started just getting lukewarm. All rads are bled and the TRV's have been checked with no probs. The supply pipe to the TRV is very hot but the rads are not hot - I thought the TRV would be at fault but the valve pin seems to be moving freely. A gasfitter today looked and advised all looks ok so he'd advise a powerflush for £600. The system was powerflushed 5 yrs ago so is this unusual to need another flush so soon after the previous one?

Please advise as I don't want to think i'm being ripped off. Thanks!!

 

[Barry98]

have you been adding chemicals to keep it topped since last power flushed ?

bit like you do anti freeze in your car ?

 

[easylife]

check the pump is not bloked up inside in the impeller ive just cleaned one out that was solid

 

[dancinplumba]

is there a filter fitted ?

 

[SimonG]

I'd be looking at the pump first.

 

[PlumbBobBob]

if it is hot up to the trv and the hot is not passing i would say the trv is at fault give it a tap, not too hard, on the side may unstick it.

 

[Syty]

Try to push down and up pin from TRV. It helps sometimes. Drain one of the radiators and see if water is very dirty
Is the other valve fully open?

 

[wolvesdave]

have you been adding chemicals to keep it topped since last power flushed ?

bit like you do anti freeze in your car ?

No chemicals have been added since the last flush.

 

[wolvesdave]

thanks for all your pointers - I'll investigate further at the weekend... it's gettin coooold