Overheating Worcester combi

Joined
11 Dec 2003
Messages
14
Reaction score
0
Country
United Kingdom
boiler: Worcester 240 combi RSF (about 2/3 years old)

All of a sudden our boiler wouldn't fire up for either the heating or hot water. It made the noises indicating that it may light any minute, but the pilot light just never sparked. After a little reading I discovered that it may have automatically switched itself off due to overheating, so I pressed the reset switch and hey-presto it fired up ok. However, after a few minutes it switched itself off again and the reset switch popped out.

I've tried turning the thermostat right down to minimum, but both the hot water and radiators get very very hot. A very tiny amount of water is also dripping from the bottom of the boiler. The boiler also sometimes made a screeching noise (i guess the pump?) - could this have contributed to it's failure?

The pressure on the gauge is just over 1 bar.

Can anyone suggest possible causes/solutions (if there are any!)?

thanks very much
 
Sponsored Links
Joined
24 Jul 2003
Messages
24,294
Reaction score
1,417
Location
London
Country
United Kingdom
Is the boiler on even with the CH wall thermostat turned down and no tap open, while it's doing this?
 
Joined
11 Dec 2003
Messages
14
Reaction score
0
Country
United Kingdom
hi ChrisR - Yes the boiler remains on, but i don't have a wall thermostat - only the temperate control dial on the boiler itself.

What I've done is turn the central heating to the 'on' position, turned the hot water to 'off' and turned the temperature control right down to 'minimum'. After leaving it like that for a few minutes the radiators still getting incredibly hot and the boiler just shuts itself off (the reset switches pops back up).

Could it be a sludge/air blockage problem? would bleeding the entire system help in any way? When we first moved into the house there was a slow leak, so for a while we kept refilling the system every 2 weeks or so.
 
Joined
24 Jul 2003
Messages
24,294
Reaction score
1,417
Location
London
Country
United Kingdom
Diverter valve is possibly stuck in the hot-water-providing position. So the boiler thinks it's providing HW but it actually heats the rads. Boiler looks at the HW temp sensor which doesn't get hot because the water's not going that way, so it gets hotter, & hotter....

It would depend on the boiler's wiring, but the boiler may heat the rads if you turn the CH off, as well.

SOmetimes the stuck valve will come free if you turn the hot tap on & off several times. Turn the CH off & try it.
 
Sponsored Links
Joined
11 Dec 2003
Messages
14
Reaction score
0
Country
United Kingdom
Tried as you suggested, turned the hot water on/off about 5 times (do i have to let it fire up fully before turning off each time?), then turned the tap off and turned the heating on (still with temperature control dial at 'min'). However, the radiators still burn up. The hot water also seems to be a lot hotter than I ever remember it being.

Is there any way to budge the diverter valve manually (bearing in mind that I'm an uber-amatuer :))?
 
Joined
11 Dec 2003
Messages
14
Reaction score
0
Country
United Kingdom
Ok Chris, I'm pleased to say that the boilers now working! I think the tap cycling you suggested did after all do the trick, so thanks very much indeed - you've saved us from having a cold, cold xmas!
 

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.


Are you a trade or supplier? You can create your listing free at DIYnot Local

 
Top