hot water only when heating on

[awni6]

Hi everyone, thanks for all the active participants in this forum.
I have a problem with the hot water only functional if the heating is on.
I have a fully pumped conentional central heating system with indirect HW cylinder, a programmable time switch, three port mid position valve, cylinder stat, room thermostat.
when I set the timer switch to operate the hot water only, the boiler doesn't fire up & no hot water, but when I switch the heating on and provided the room thermostat is up then boiler kicks in & water in cylinder does heat up, now when weather is warm I don't have hot water unless I activate the immersion electric element.
could it be the cylinder thermostat, 3 port valve? Any help will be much appreciated.

 

[stevetheplumber]

most likly to be the three way valve try fitting a new motor

 

[awni6]

Tanks very much for the quick reply steve, anyone else has any other opinions?

 

[leakylea]

steves got it covered, you could link the stat out to test it

 

[awni6]

Thanks leakylea for your reply, I'll follow your recommendations. Thanks again.

 

[gascob]

doubt it will be the motor, the valve rests in hot water only mode...i would be looking at either the full valve or actuator...

 

[oeg]

The valve doesn't switch the boiler/pump on, the call for heat from the cylinder stat actually switches the boiler on, so regardless of the valve position, when you call for hot water from the programmer, and the cyl.stat is also calling for heat, the boiler should come on.