Boiler firing up in th middle of the night?

[mice]

Hi, I hope someone can help me.

I have a problem that my boiler is firing up and heating the bedroom/ bathroom radiators in the middle of the night when both heating and hot water should be off, making it a bit hot and wasting gas!

The timer control is set to heating off and hot water on for an hour or two in mornings and evenings, but the boiler was firing and some upstairs radiators on at 2am. Turning hall thermostat down to minimum makes no difference, so it seems the boiler is firing up when all controls tell it it should be off.

I have a 10 year old (new build house) Ideal Classic LXRS boiler, Sunvic Select 207XL timer control, Drayton ACL Hall Thermostat, standard Gravity Hot water (cylinder in airing cupboard), acl lifestyle 2-port motorised valve and Myson Compact CH Pump.

Assuming it was something wrong with the timer control, I replaced that but it made no difference. Does anyone have any ideas?!

 

[seco services]

if its a 2 port valve you should have 2 of them

or one of these

 

[mice]

Thank you for that - there are indeed two 2-port valves (one was hiding behind the towels!) - is that significant?

 

[seco services]

poss the heating one is sticking open or the micro switch inside is sticking.

 

[kevplumb]

where is the boiler

 

[mice]

kevplumb - the boiler is in the kitchen/utility room downstairs.

seco - thanks. But if the heating 2-port valve is sticking, would that cause the boiler to fire up when neither heating nor hot water were on?

 

[kevindgas]

the only thing i can think of is that the cylinder stat is creating an electrical circuit when the temperature drops enough to make it switch to demand and that is causing the boiler to fire up

would look at the electrics first

 

[seco services]

seco - thanks. But if the heating 2-port valve is sticking, would that cause the boiler to fire up when neither heating nor hot water were on?

yes cause the valve has a perm live to it.
the programmer only sends live to the motor to open the valve.

if it does it again check the lever on the end to see if it has resistance or is floppy to push.