worcester 9.25 combie boiler

[alanbradley]

Hi,
I have a worcester 9.25 combi boiler about 12 years old, last serviced 2 years ago, the problem now is that the system runs for about 30 min (central heating) then goes out, any ideas

 

[weargas]

could it be a 9.24?

 

[alanbradley]

opps missed the .01 off,
any ideas why the bolier keeps cutting out after about 20 min operating

 

[weargas]

there are a few things that may be causing it, this is the order in which to test,
1. pilot flame whilst standing and then when boiler has fired,
does the flame look blue and sharp or yellow and floppy? it the flame burning across the tip of the thermocouple?

2. thermocouple, you'll need a thermocouple tester to test properly but there is a rough way.
light the pilot light and let it stand for a minute or so. turn the grey pilot light button on the gas valve clockwise and let go of it so it springs back. the pilot should have gone out. at the same time listen for a bareley audible click inside the gas valve. how many seconds between turning off the pilot and the click??

3. overheat stat, it could be poor connections of the split wires to the stat, it could be the stat cuts off at too low a temp or the boiler may be overheating in which case the boiler is working as it's designed and you need to address the overheat problem.

4. the gas valve, it could be the mag unit on the gas valve that's gone but it's more likely to be one of the above if it's staying on for a short while before failing.

 

[alanbradley]

thanks for all your help, things have just got worse, now the boiler has gone out and won't re-light, what would be your guess as to the most likley fault
alan

 

[COG]

You say your boiler is 12 years old BUT there are 14 differant 9.24 models B/F , O/F, FSN, FSP, with Electronic, Economy mk1 mk2 and various in between models some with perm pilots some with electronic ignition , so basicaly its a bit if a job to pin down your fault unless you can state the model on the data plate. but at 12 years old its a bet you have a circulation problem .plus what is the first four digets on the serial number that will give the age of the boiler.

 

[alanbradley]

Hi,
Thanks for that,
have looked at the boiler and with all things found a shed load of numbers so don't know which are relavent but here goes
s/n 9005013394
product code E9.24BF
THEN 9.24 BALANCED FLUE G.C NO 47-311-05
If any of that makes senes to you would welcome any thoughts you might have,
alan

 

[COG]

The E on your model stands for economy and it does have a permenant pilot so all the Weargas listed the most probable faults , all of them should be seen to by a corgi reg eng (to ccn1) but personally i would replace the limit stat regardless as they dont have a long life after a few drop outs as your described. I f your boiler was makeing any noises "kettling"prior to going out then you have poor circulation and on a 14 year old boiler you would be beter off replaceing it then repairing it blind.