My rads won't come on except when the timer is set to hot water?

Question

My rads won't come on. The thermostat is set high and the times is set to 'heating constant' but the cirulating pump stays off, and the boiler too. However, when I switch the hot water to constant (with the heating still constant), the boiler comes on and the rads too - is this a fault with the three way valve - should I replace it - can it be serviced?

Answer 1

yes it is a fault with the three port valve,and no it cant be serviced,if this fault has just occured then you need to replace the valve,sometimes these valves are wired wrong which will make it work so that you get hw on its own,but the hw needs to be on to get heating.if thats the case then a bit of alterations to the wiring between the programmer and the cylinder stat is reqd

Answer 2

If you have a 3 port valve on a hot water priority system the cylinder stat maybe faulty ie directing the water to the cylinder all the time, to check this turn the cylinder stat down manually and see dose your heating work. It maybe the wrong type of programmer is fitted to suit your system layout.

Answer 3

most controlers will only switch heating on if the hot water is on generaly speaking a three port valve switches between hot water and both hot water and heating sounds like you have got the wrong sort of controller

Answer 4

Im not a plumber, but I think its OK...mine used to do that...you had to have the hot water on for the radiators to work.. you could have hot water whenever, .............but it was an older system, the combi boiler in my new house is different.

Answer 5

If nothing has changed recently (parts), then I would say the diverter valve, but are you sure the programmer or the wiring hasn't been changed?

Answer 6

the three port vavle is notorious for going faulty ,better to spend a few quid and get it changed.