Wiring in underfloor heating - Heatmiser UH4

17 Sep 2004
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United Kingdom
I'm wiring in a wet underfloor system already laid under concrete, to connect to a new Baxi combi.
All good, except that the wiring instructions for the Heatmiser UH4 are a scant.
I've worked out the thermostats, actuators, mains in, and ufh pump.
The plumber put in a Honeywell 2 port motorised valve, and I'm assuming this is what Heatmiser are calling Boiler Enable?
On the wiring diagram, though, it says "LS AND LR IS VOLT FREE", but the Honeywell valve has 5 wires, not the 3 on the Heatmiser wiring diagram.
Any thoughts, please?
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What other heating do you have?
Do you have other valves and/or pumps?

As for your 3 wires and 5 wires query, the diagram shows the valve :


but I don't know if that is an advisable method.

Volt-free is a daft name. It just means that the terminals are not connected to anything else so you can use any voltage on them.
Ahhh. Thanks for that.
No, no other heating source(s). Just the u/f heating.

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