My boiler wont start and heat up the radiators but its fine at heating the hot water when I turn the hot water taps on. The seperate timer control seems to working ok but even if I overide the timer the boiler will still not start. I also have a seperate wall mounted analogue thermostat and even if i turn it up the boiler will still not turn on even if the timer says it should be on. What could be the problem?

Is the thermostat wireless? Does it have a battery in it?

Maybe the boiler has just realised that it’s spring and that you don’t need heating. It’s kinda your boiler’s way of telling you to MTFU cos it’s hardly like you live in Scotland or anything 😉

Good luck with it, and I hope to catch up with ya soon!

does it have a pressure valve on the front? What does it say? A boiler won;t start up if the pressure is too high or low.

Thermostat is a wired manual type not wireless and the bolier is showing good pressure at 1.5 bar when off.
Bananaworld- I’m not the one who is suffering its the GF. I can quite happily have the heating off. We must catch up for a ride soon so I can have a play on your homebrew bicycle shaped object!!

Knackered thermostat? Do you hear a click from inside as you turn it up / down past the ambient temperature?

Pilot light gone out.
Pump nackered.
Water pressure.
Valve stuck HWS/Heating

I’d look at the motorized valve for the central heating if you say you’re getting hot water on demand, but no heating.

The motors inside the valves eventually burn out as they are designed to jam when the valve is open. The motor drives against a spring which will automatically close the valve when the motor is de-energized. Not a very sophisticated solution, but it works! These motors cost about £7-10 and are easily changed if you have a bit of heatshrink sleeving, solder and an iron.

There are different ways central heating is configured and wired up and the set up I have is called an “S-Plan”. With a combi, circulators and valves are often built into the boiler casing. Your boiler manual and Google will enlighten you as to what you have got. If you haven’t got the manual, see if you can get it from the manufacturer’s website.

What happens in many systems is the programmer switches on the hot circuit and all this does is energize the motor in the valve.

When the valve is open, a micro switch inside the valve casing is made, closing a circuit that runs back to the controller circuit board in the boiler. This in turn starts the circulator (central heating pump) and it also “calls” the boiler into action. Soon after your rads should get warm.

If you locate the valve body, there will be a small overide lever which you can actuate. The lever may be a little stiff, but when drawn across to the open position, this should enable the central heating to kick in. It will stay on permanently until you release it, thus rendering the programmer redundant.

So that’s where i’d start. Good luck and let us know what the actual problem is/was.