No call to heat on CH

10 Jan 2007
Reaction score
United Kingdom
Boiler Suprima 50 with latest PCB/side unit.
New Timer Pot EP2002
Thermostat switching live ok but not effecting control of CH when boiler on.
Diverter valve replaced 18months.
Will give 240v to boiler with HW to on.
No 240v with CH only switched on and thermostat to max.
Heat to rads intermittant with CH on with HW also on.
Will give heat to rads till tank full.
Pump seems to work ok.
Lamps on diverter valve on with timer/controller set to HW and CH.

Is it the diverter valve again (myson power extra)

Thanks in advance

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Firstly, the boiler should have a permanent live feed.

I will assume the 240v to the boiler you mention is actually a seperate "call for heat" connection.

If the call for heat connection is not being provided in CH then the obvious failure point would be the microswitch in the diverter valve. The Orange wire should become live when its in any of the permissable positions.

Thanks for the reply

Will check micro switch/ 240v on orange wire.
Is the switch a separately replaceable item, or does the whole head nee replacing.
Any ideas on why in six years of system that the diverter value has faulted twice.

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