Boiler keeps starting up for no reason?

[octagon]

Hi,

I've got an Ideal Mexico boiler (Super CF3/100) and a "Lifestyle LP722" timer switch.

Now, I've noticed over the past couple of days that the boiler is firing up at odd times - when the timer switch says it should be off (we've got the heating switched off and the water set to come on for an hour in the mornings and evenings).

When the boiler fires up at these odd times, both red lights on the timer switch are off and setting the timer switch to CH-OFF, HW-OFF doesn't have any effect.

It doesn't seem to stay on for long, but I've noticed it a couple of times in the past day or two.

Is that normal?

It just happened a few minutes ago and I tried switching off the fused electrical switch next to the timer - which cut out the boiler immediately. Switching it back on, the boiler started up again.

I'm thinking that the timer switch must be faulty. Has anybody seen anything like this before?

Thanks.

 

[ollski]

yes, from an s plan 2 port zone valve usually.

 

[ChrisR]

It's more likely to be a valve stuck open that a faulty timer, what do you have?