St9400c programmer playing up ?

[swampydrill]

Got a honeywell st 9400c programmer on a gravity fed system. Been having issues getting hot water, set programmer timings for 3 times a day but then no hot water. Changed the actuator valve head but still playing up. Is it likely to be the programmer or hot water thermostat?

 

[muggles]

Could well be, there was a dodgy batch a few years ago that did all sorts of weird things.

 

[swampydrill]

If i put the programmer to continuous and then increase the water thermostat, the boiler should kick in, if it doesn't then it could be thermostat for water or programmer. Are water thermostats pretty teliable

 

[fezster]

When you press the HW override button on the programmer, does the relay "click"? There's some past threads on this problem. If the light comes on without the click, you may be able to (temporarily) fix it by switching off the backlight. Honeywell will also replace the programmer if it is part of the bad batch.

 

[swampydrill]

The green light was on indicating hw was on and boiler was on. The pipe at top of hw cylinder was cold so not heating the water. I pressed overide heard a very faint blip but no click. I noticed a panel light was out (seems to go out when turn room thermostat down so guess its for that)when reset it on again, the boiler kicked in, maybe have just overridden the thermostat.posted a picture of system

 

[swampydrill]

A pic of wiring

 

[swampydrill]

Changing the programmer seemed to sort the issue out.