Worcester 280 RSF hot pump

[evertsen]

Hi

My boiler keeps cutting out after about eight minutes on both central heating and hot water, the sequence seems to be;

Switch on boiler, demand hot water or central heating - Fan starts - igniter operates - boiler lights.
After eight minutes or so, flame cuts out - igniter starts - fan continues to run.

The diverter valve operates ok and the pump runs, however, the pump casing gets very hot. Boiler pressure is 1.4 bar

After about ten minutes the boiler re-lights and the sequence begins again.

Any help would be much appreciated.

Dave

 

[tomy]

Sounds like your pump has had it or your sytem is full of air and it cant pump water around , are all the air vents bled ?

 

[evertsen]

tomy,

Thanks for taking the time. Which air vents, boiler or system? How can i check?

Thanks very much again.

 

[evertsen]

In the interest of adding some personal experience to the forum, here's another post on progress with my bothersome boiler.

Changed the pump but the problem remained, in fact the boiler wouldn't light at all! so i carried out the following checks.

Started central heating demand, the sequence seemed to be ok - diverter valve operated - pump on - fan on - igniter on, but no pilot light.

Repeated a start and connected a meter to the pilot valve terminals on the ignition control board. The meter showed 6 volts at the point when the ignition sequence began which seemed to be correct. I then measured the coil resistance of the pilot valve and found it to be open circuit. Great i thought, the coil's been gradually breaking down and cutting out the pilot which gave me the earlier symptoms.

The next phase is a bit annoying. i bought a new gas valve (£115) and found that the pilot valve solenoid was removable from the gas valve, so i fitted only the solenoid to the existing valve and it worked, the boiler lights and the running is sustained. I wonder if these solenoids are available individually?

I still have problem though, one which has been manifest for about a year and i don't think it's connected with the previous fault.

The boiler occasionally starts without any demand to do so!

With the boiler power on and no CH or DHW demanded (central heating controler set to off) the boiler occasionally goes for a start! fan on, pump on, ignition and the boiler lights, and then shuts down again. The green demand LED does not light which suggests to me that the flow switch might be OK, but i can stop these spurious boiler ignitions by disconnecting the domestic hot water sensor, which of course disables the DHW demand control loop.

Any thoughts would be greatly appreciated.