Worcester Bosch 28cdi PROBLEMS

[duncan1984]

Firstly, hi.
I have a 28CDI combi boiler, i tested the heating for winter the other day and it was fine, nice hot radiators etc.
Today i switched it on (heating) and to all intense and purposes, it works fine apart from it is not heating the radiators to a hot temp, just luke warm. The radiators do not need bleeding. On going to the cellar to look at the boiler, i can hear the pump running. When the boiler ignites to heat the water, it does so for about 15 seconds and then the flame goes out again. The problem with the luke warm radiators, appears to be the boiler not heating the water long enough. Any ideas what it might be?? British Gas is coming on Thursday, but im just curious what it might be. Hot water for the taps are fine.

 

[MarkCharnock]

Sounds like either a problem with the pump or maybe a blockage somewhere? How dirty is the system?

 

[duncan1984]

the pump seems fine, i wouldn't know how dirty the system is. the radiators do get warm, but not hot. when the ignition starts, it ignites, and stays lit for aroun 15/20 seconds then shuts off again, to leave the pump, pumping. so the pump is pumping water around but just warm water. It re ignites at the intervals it would normally but, only stays lit for the 15/20 second leaving the water warm but not hot.

 

[Ihavenojob]

Could just be that the thermostat knob spindle has snapped so its not turning up fully,do you use this to turn it on&off?