Any Central Heating Engineers On Here?

A long shot but.... we have an old style central heating ie not combi and the boiler fires up fine for the hot water but the boiler will not fire up for the central heating. The thermostat is clicking on and off ans has been tested working. When I press the button to put the central heating on it clicks so I assume the control box is working, anyone have any idea's? thanks in advance


I'm not a central heating engineer, but it sounds like a diverter valve to me (diverts hot water to/from taps/radiators), not too expensive.

Does the boiler not even light up for the heating, if not then it may be one of the controls telling it to do so, if it were the diverter valve I would have thought the boiler would light but the hot water being produced would not reach the radiators due to the valve being out of position.

Can thoroughly recommend joining here for an experts opinion.…318

Original Poster

thanks guy for taking the time to reply,

greg_68, no the boiler does nothing when switched to central heating, the hot water fires the boiler up straight away - I will try to check the electrics on the controls this evening but sure they are all in there and ok so maybe a faulty unit however it does "click" as it supposed to do to "initiate" the firing up of the boiler - thanks, will also try that website - thanks

I had a similar problem at the weekend. Mine is a combi boiler and was giving hot water but when the heating was requested nothing happened, even when the heating was on override. I had a Drayton Wireless thermostat and got told by a number of plumbers that they were rubbish. Replaced it with a Honeywell one and all is now working again. HTH.

Original Poster

thanks for that but i have tested the thermostat and it is working fine but thanks anyway

Original Poster

It seems the central heating will start now start once the hot water is turned on - I can now turn the hot water off and the heating remains on however If the water has been turned of for about an hour the central heating will not come back on again by itself only when the hot water is switched on - any other suggestions? thanks


first try step1-

bleed all the radiaters individually

Original Poster

SOLVED - the 3 port switch was faulty - thanks to all
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