Lifestyle LP241 replaced with Hive CH issue

[ericmark]

OK managed to measure voltages (All AC voltages) this evening

HW + CW Both on (Boiler On). Orange = 240V, White = 240V, Grey = 0V

HW Only On. (Boiler On) Orange = 240V, White = 28V, Grey = 0V

CH Only On (Boiler off??). Orange = 0V, White = 240V, Grey = 15V

As said, CH only grey should be 230 volts, the valve

is an odd device, and it can result in some odd voltages. @stem has shown how it is wired, and the boiler is run direct from the tank thermostat when set to DHW or DHW plus CH, and the 230 volts at the orange is actually a back feed from the boiler.

So if SW2 is faulty, then you will not get CH on its own.

 

[stem]

So if SW2 is faulty, then you will not get CH on its own.

This is correct, but without a live on the grey wire, SW2 will never operate, and that's what we're missing.

 

[LordWhiteley]

Well luckily I do have a spare Drayton MA1 3 position valve I can swap over...

 

[stem]

With a new valve, you will still need to fix the HW off signal to its grey wire, without it, it will not move to CH only.

 

[LordWhiteley]

Yes I missed that point . I'll try an measure the HW off, HW on & CH on the terminals on the back of the Hive control unit. If they match those measured on the 3-valve, in particular grey HW off - then the Hive unit is suspect - I also verify this by refitting the LP241 and seeing if CH on works again as it used to.

 

[ericmark]

I also realised there is a problem with the backplate, once the hub is removed to get access to the contacts, clearly you can't test if the unit is switching, lucky I have a wiring centre between the hubs, allowing me to measure.

So assuming two channels, I would fit links if you then get CH you know the wiring to backplate is OK.