Heating coming on when it shouldnt.

scousedave

Hello.
I have a combi boiler but since it has been getting cold and the heating being on the boiler fires up and heats the radiators when it shouldn't as well as when it should.
I often hear the boiler fir up and the rads starting to heat uo beut when I look at the time switch it says off.
Im inclined to think that it is the timer that might be faulty but after your advice,
Thank you

jbainbridge

Is the boiler in the house or garage? Could be a frost stat.

scousedave

It is in the house...thought of that but the boilers in the spare room and the boiler is coming on during the day when the temp is well above the, say 5 degrees for the frost stat.

Lobsta

We had a similar issue, the rads came on when the boiler was heating the water. It was a valve sticking.

scousedave

Lobsta wrote: »

We had a similar issue, the rads came on when the boiler was heating the water. It was a valve sticking.

I don't think its that also as the heating comes on at irregular times but not when water is being drawn, If this were the case I agree with you it could be a sticking valve but the heating comes on totally independent of the hot water supply being drawn upon.

Lobsta

Our combi has a reservoir of water that is kept hot so when you want hot water its there immediately as its set to on demand. Ours is a worcester bosch.

FOREVER21

Lobsta wrote: »

Our combi has a reservoir of water that is kept hot so when you want hot water its there immediately as its set to on demand. Ours is a worcester bosch.

We have a new boiler 2years old also a Worcester Bosch and like yours it has a pre heat setting which means the water is instantly hot when tap turned on, mind you it uses more gas this way as the boiler clicks on/off all the time to ensure the pre heat works, after the first year service I was talking to the engineer and he explained this,I have now turned the pre heat off.
Regarding the original post, I wonder if they have this pre heat mode although I doubt whether the pre heat would be on long enough to send water around the rads.

Mr_Ted

Make, model of boiler and controls installed will be needed

ilikewatch

I get exactly the same with my Vaillant Turbomax Pro boiler and Vaillant VRT 340F wireless programmer. Sometimes it just switches on and starts heating the radiators when the timer is set to off and house temperature is way above that required to trigger the heating. Vaillant suggest that it could be because of interference from another nearby programmer, or low batteries - I have changed the batteries and this didn't help.

Andehh

We have an issue with our pressurized system where the boiler comes on at random after long spells of being on, it was come on for 5-10mins then shut itself off, then come on again 15mins later...rinse & repeat job. All caused by the below valve sticking....

http://www.plumbarena.co.uk/product/honeywell-v4043h1056-22mm-2-port-zone-valve/?gclid=CLKT2--ZjbsCFdHItAodyVAAIA#.Upo26sTIb14

macman

Is it always at the same time of day? My combi fires at midday every day of the year for about 3 seconds: it's the programmer's 'pump exercise' mode enabled, that is designed to stop the pump sticking over the summer months.