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Rick Ridley
Rick Ridley, UK Heating Engineer
Category: UK Plumbing
Satisfied Customers: 1561
Experience:  30 Years on the tools, now retired, Ex CORGI
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I have had a heating engineer look at our regularly

Customer Question

I have had a heating engineer look at our regularly serviced, 2008 Worcester Greenstar 24R1 boiler. The boiler fires up for CH & HW no prob but after the room stat switches it off it refuses to ignite when the room stat calls for more heat. A loud clicking like a relay can be heard in the boiler. Switching it off and waiting for a few minutes seems to clear the fault. The blue light does not flash. He power flushed the system, also found grit or debris in a condencing trap (I think) - it was a small clear plastic box/tray inder the vent. He is stuck to know why the boiler won't fire up and because of the cost of Worcester parts is reluctant to replace parts e.g. fan, PCB. He now recommends a new condencing combination boiler in a different location. This boiler install cost £3600 seven years ago, I've already spent nearly £900 so far and am reluctant to fork out nearly £3000 for a new boiler which we don't want. Help please!
Submitted: 1 year ago.
Category: UK Plumbing
Expert:  Andrew Smith replied 1 year ago.

It does sound like the PCB is at fault. Does the boiler fire all the time correctly for the hot water?

Expert:  Andrew Smith replied 1 year ago.

You have a condensing boiler but a standard system. I take it you have a cylinder?

It may not be a boiler fault - it could be a system fault.

Customer: replied 1 year ago.
Thanks for a prompt reply. Didn't expect one tonight! Pretty certain it does fire up for hot water correctly. To avoid the fault appearing we are running the room stat at 24C, far higher than the room would ever get with just one small radiator on. (TRVs stop the house from getting too hot.) The hot water is set to come on at 0700,1200 and 19.00 and the boiler has, to my knowledge, always fired up. I'll observe it closely tomorrow.
We do have a cylinder.
What kind of system fault would cause this?
Thanks for your help. I'm looking forward to reporting back to the engineer.
Expert:  Andrew Smith replied 1 year ago.

I am thinking the motorised valve.

When you turn the heating on the valve should open fully and fire the boiler.

When on hot water only then the valve will be closed.

But, if it always works with the room stat turned right up, do you not think it is a faulty room stat triggering too high?

Customer: replied 1 year ago.
Thanks, ***** ***** back to the engineer re the last posting.
Regarding the room stat, the only reason I have set it so high is to keep the boiler on all the time, thus avoiding the fault. If I set it to, say, 21C once 21 was reached the boiler would then switch off but refuse to fire up when the room temp dropped. I so don't what a new boiler after only 7 years and have it moved back to the garage with a vent in the new roof! Or spend another 3K as well.
Thanks again.
Expert:  Andrew Smith replied 1 year ago.

No problem - let me know what he finds

Customer: replied 1 year ago.
My hands-on neighbour stepped in and recommended fitting a new PCB, which we did. All OK, just need to get the co/co2 checked.