Is my thermostat broken?

[sniperuk]

I have a problem at the moment. The boiler fires up when i switch the hot water on but it does'nt fire up when i switch the the heating on. The thermostat still clicks in when the heating is switched on just the boiler does not fire up. Any ideas

[heathfield]

One answer might be that you have a leak, and the pressure in the system has fallen. There should be a pressure switch somewhere in the boiler that senses this, and it would make the boiler think there's not enough water to operate safely. Could also be that this switch has gone faulty, (as happened with me when I had the same symptoms as you're experiencing).

[sniperuk]

There is no pressure switch on the boiler so not sure how else to check

[pilotlight]

sniperuk, What is the make and model of the boiler ?

[sniperuk]

ideal classic

[pilotlight]

sniperuk, There are a couple of things you could check. Firstly, make sure that the room thermostat on the wall has not been inadvertantly turned down. If not, you could check the motorised valve that should be open to send hot water to the cylinder ( it is possibly sited in the cylinder cupboard, near to the cylinder ). If it is a 2 port valve, meaning only 2 connections, it will have a small lever on it. You can slide the lever across the opening to manually to open the valve. If the boiler then fires up, this will tell you that the motorised valve was not opening previously by means of electronic control, and will require replacing ( but possibly an electronic fault ). Other than above, you will probably require the services of a heating engineer.

Hope this helps.

[sniperuk]

I think i know what you mean i have a grey box with 3 pipes coming from it. there is a leaver which when pushed it moves from W TO M TO H. I have tried this already and set to M and it still does not fire up is that what you mean

[turboped]

I'm not sure if the manual lever on the valve will make the contacts to send the feed to the boiler and pump, but you could try putting the valve back to auto, turn off the HW at the programmer, turn on the heating and check to see if the pump starts, if it does the valve is opening therefore the problem lies between the valve and the boiler or at the boiler its self.

[turboped]

Or even easier and more conclusive to test the valve just hold on to the lever gently while someone turns the heating on and off, you will feel the lever move if the motor in the valve is working.

[sniperuk]

Which setting is Auto as mine has W,M,H

[turboped]

I think the letters are W - Hot Water M - Mid position H - Heating, I'm guessing a little.

[turboped]

Sorry Mid Position = Both HW and Heating

[turboped]

Sorry again just re read th response, originally I'd assumed you had moved the lever to hook on to the manual overide position as is the case on some valves as long as the lever is free to move then its in auto.

[sniperuk]

No movement that i could feel

[sniperuk]

It does move when i manually push it freely

[turboped]

What happens to the valve when the programmer calls for HW only?

[sniperuk]

Nothing the slider does not move. I think it is this but how easy are they to change. Is there any water to turn off as well as the electricity?

[turboped]

Sorry its taken so long to respond. But does the pump and boiler turn on when the programmer calls for HW only. It may be easier to google the valve manufacturer and phone their tech desk and make sure that the valve is at fault before you proceed, if it is the valve motor I know the 'Honeywell' ones are easy to change just the motor in side the casing only with a bit of dexterity and common sense, no need to turn off water but ensure it is isolated from the electric supply.

[sniperuk]

Thanks ev1 for all your help but i changed the synchron motor yesterday and all is fine ok now