potterton combi 80 poor CH

[tumbleweed2727]

i have a potterton combi 80
the problem is that the boiler seems to be working, eg firing up giving hot water etc but the rads are just not getting hot what so ever. drained down the system a couple of times, bled the rads, checked all the trv's. put cleaner through it. I have turned the rads all off but one and this even only gets to about 2/10 on a hot scale. The return pipe from the rad is hotter than the flow pipe,is it possible that someone has fitted this system with the help of ray charles or stevie wonder or is it a common problem.
When i drain down the system, the water which comes out seems to be clean and not black or sludgy.
The flow pipe from the boiler is extremaly hot whilst the return is luke warm which would indicate a blockage or sludge but nothing is making sense
any ideas??
Geoff

 

[Agile]

You seem to have limited flow rate through the heating.

Pump is the first thing to check ( see FAQ ).

Tony

 

[tumbleweed2727]

it had a new pump about 6 months ago? hummm

 

[Agile]

I would check the pump first as thats easy. The eye may well have been blocked by dirt you have loosened.

If thats really OK then it sounds as if the diverter valve has failed or you have a dripping hot tap.

There is a little trick that a pro can use to "encourage" the diverter valve to move.

Tony

 

[bengasman]

This model is known for the problematic diverter design, they often get stuck. As Tony said, check the pump as it is easy, but my money is on a duff diverter.