Boilermate issue

[Biggsmig]

I have a boilermate OV. The house has 2 thermostats, one upstairs and one downstairs.
When the thermostat downstairs calls for heat the upstairs radiators upstairs get hot despite that thermostat being set to a lower temp.
The electrics have been tested and seem to be ok.
Any advice appreciated

 

[CBW]

Zone valve not closing properly, or someone has linked something out. What happens if you use upstairs only?

 

[Biggsmig]

Thanks for quick response. Downstairs thermostat off. Upstairs on. Rads upstairs hot. Downstairs cold

 

[Harry Bloomfield]

Find the upstairs zone valve, see if the valve actuator operates when the downstairs stat is turned up and down. If it does, then obviously there is a wiring issue, or it by design.

If it doesn't operate, then the valve for upstairs is passing - allowing heating water to flow, when it is supposed to be closed.

 

[Biggsmig]

Harry. Thanks for the reply. The upstairs actuator doesn't operate when downstairs thermostat is turned up.

 

[CBW]

Thanks for quick response. Downstairs thermostat off. Upstairs on. Rads upstairs hot. Downstairs cold

Faulty zone valve for upstairs then, must be letting by.

 

[Harry Bloomfield]

Harry. Thanks for the reply. The upstairs actuator doesn't operate when downstairs thermostat is turned up.

When boiler initially starts up, to heat up what should be the downstairs only, feel the pipe either side of you upstairs zone valve. It should be cold. If not it is passing.

 

[Biggsmig]

Thanks for all the help. I'll get the valve changed