Central heating zone valves - 5 or 6-wire?

fwor

On my central heating I've got two zone control valves, one or both of which is causing a problem, with the boiler staying on indefinitely (or until I turn off the mains for a few hours and then turn it back on again!).

I was planning to replace both, but the problem is that although both visually look the same, one has five wires, and the other has six (with an additional white wire on the latter).

However, when I look at the connection block that both are wired to, I find that the sixth (white) wire on the one with six wires is not connected to anything.

Does this mean that I can replace both with five wire actuators?

TIA!

Le_Kirk

Could you find the manufacturer's details from the zone valves and post here please.

fwor

I can but they might be too detailed! The manufacturer is ACL Lifestyle (which looks like it's a division of Drayton) and the part number of the 5-wire one is 679H308-30L1 and the 6-wire one is 779H335-30L10.

Looks like the 5-wire one is obsolete but the replacement is relatively easy to get, while the 6-wire one is obsolete.

As it looks like the 5-wire one is the one with problems, perhaps I should just look to replace that one first. Unfortunately mine pre-date the pushbutton-to-remove arrangement on the current design, so I may have to replace the whole valve rather than just the actuator :-(

fwor

Ah well - looks like my answer is "no".

Replacement part numbers appear to be ZA5/679-2 and ZA6/779-2, and you can't just replace a 6-wire actuator with a 5-wire one - even if the sixth wire isn't used.