Worcester 28cdi heating problem

[Benjibalz]

I've a problem with a 28cdi not firing for more than a minute or two on heating. Ive ruled out scaled/sludged HE as it fires continuously on hot water. It has a new flow thermistor and a 2 month old diverter so they should be fine.

Filling and bleeding the system is a long old process, but all with all rads bled two rads fail to heat up (balancing the system was the original reason for my visit). I'm wondering if the problem is poor circulation caused by the air rather than a problem with the boiler itself. Worcester said this was unlikely but I'm scratching my head a bit as the hot water working fine rules a fair bit out.

Obviously, the two rads not heating are probably due to the boiler not staying on for long enough and I have removed the CH stat control knob to make sure its actually moving the internal part of it which it is.

Any thoughts peeps?

 

[corgiman]

Bet the diverter valve is not returning to Heating position

change it

 

[gremlin16]

change it

second thoughts

 

[Benjibalz]

I had kind of ruled out diverter as I only put a new one in recently but I guess that doesnt mean its not faulty. Seeing as 7 out of 9 rads heat up my circulation theory is probably c**p as that should provide enough circulation for the boiler not to reach temp.

Is there a way to make the diverter return to heating without removing it or do you reckon I should just pop in a new one?

 

[nickso]

if the pump is ok i would ignore the boiler for now.

if only two rads are not heating i'd have them off the wall and check them and the flow through those pipes, sounds more like a blockage to me.

is this 28cdi on an open or sealed system?

 

[corgiman]

OOPPS

thought all the rads werent heating up

shame on me, aint the div valve.

listern to nickso and ignore me

 

[Benjibalz]

Cheers nikso, think thats it. Went back today for a quick visit and managed to get one of the cold rads hot when I stuck the boiler on full whack with the commissioning function. The last rad seems to have a blockage as the flow warms up but heat stops at the valve. I popped a new trv on with the system bunged(it is vented by the way), but didnt help.

Time was of the essence as the fella wanted to p**s off to cyprus for a week which was fair enough so will be poppin back to remove that rad to check for a big blob of LSX on the tail. I probably should've mentioned before that is what I'd already found this on a newly fitted rad(by his mate) and cleared that blockage. The cold rad is old and a lot further away so I didnt think it would be blocked.

Anyway, Ive got a glass of scrumpy and a wedge of cheese to contend with before I have to deal with that again...TFI Friday.

PS:Keep up corgiman!

 

[Benjibalz]

Quick addendum: I did turn all rads off bar the cold one and that just shut the burner off quicker before anyone mentions it....blockage it is then..hopefully!