Central heating

[Richsmith]

Can anyone help.my heating doesn't always work.i have the hot water set on a timer.the heating seems to always work when the hot water is on but when the hot water is off it doesn't always work.occasionally it will come on when the hot water is off.so i dont think it will be the valve as it would only work when the hot water is on if the valve has seized.the thermostat clicks when you turn the heating on but nothing happens.could it be a problem with the thermostat.

 

[bhm1712]

what boiler is it?? is it a Y plan or S plan? how many motorised valves?

what timer is it?

More info please

 

[Richsmith]

It's a myson boiler.i think it has two valves but I'm not sure.dont know what the plan is.i will try to find out.

 

[45yearsagasman]

Good luck with that bhm1712.

 

[Richsmith]

The timer is a horstmann 425 tiara.the valves say A, B and A/B and it is a sunvic which turns the valve

 

[swbjackson]

When the heating is on when the hot water is off the boiler is fired by a microswitch in the valve head. Wear and tear over time can mean that this microswitch doesn't always make leading to intermittent heating when the hot water is off.

You'll need to confirm this with a multi meter before changing the valve head though. Be careful as there are 240v components and terminals inside the valve head.

 

[Richsmith]

Ok thanks