My programmer allows the hot water tank to heat as planned but not the radiators. Boiler is fine.

Could this be a faulty motorised valve? The programmer doesn’t turn the boiler on when required – does it need a signal from the valve to do this?

Help appreciated

many thanks

if you override the timer on the programmer by doing ‘extra hour’ or something does it all work fine?

If it does then sound slike the programmer not the other gubbins is at fault?

After you’ve fixed it can you come and fix mine. My boiler only fires when you hammer the front LH corner with your fist. Sounds safe enough.

Doesn’t work even when set to “24 hours”

You can normally operate the valve manually to check if its the problem, well mine can. Also could be three central heating pump sticking, particularly if its the first time its been used for a while. A few gentle traps with a hammer whilst the heating is on can fix it. When our pump stuck the boiler would cut out withina couple of minutes as the water was over heated.

As spooky says you should be able to turn the valve on manually, mine all have little levers on them.

If I remember correctly, my programmer switches on the circulation pump and the valve. The valve has a switch built in that, when the valve is open, fires up the boiler.

The microswitch in the valve head could be the culprit. You can take the control unit off the valves to check (at least you can on the modern honeywell ones). Basically the valve opens and when fully open a lever pushes the microswitch – it is the last thing in the chain to then spark up the boiler and pump (which may or may not be built into the boiler).

If you have a thermostat somewhere in the house check that is hasn’t got turned down really low and this is stopping the heating coming on.

You should be able to move the little arm over on the three way valve and then fire the boiler by turning the programmer to the hot water setting.

Its not a old Gravity Hot Water system is it? If it is you have to have the hot water on at the same time or the central heating doesn’t work.