Underfloor heating query

17 Sep 2004
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United Kingdom
Hi. I'm new to underfloor heating, and this may be a silly question, so sorry in advance if it is.
We had an underfloor system put in before laying a concrete floor.
Baxi boiler now installed, and now the manifold, pump, and all the gubbins are wired in.

There are three zones;

zone 1 has one actuator
zone 2 has two actuators
zone 3 has four actuators

Currently only zones 1 and 2 are needed, so zone 3 has no thermostat on it, and looking at the wiring, would seem to not have a power supply to the actuators.

BUT all three zones seem to be running. The floor in zone 3 is warm even though we want it turned off.

Am I missing something? Do I need to put a thermostat on to zone 3 and then set the desired temperature really low just to turn the zone off?

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If zone 3 has a motorised valve fitted check that the operating lever hasn't been latched in the manual mode. This is there to manually open the valve to facilitate filing the system.


If the lever has been left in the manual mode, the zone will heat up when either of the other two zones are operation.
There's one motorised valve for all of them.
Then are actuators for each .
You don't mean 3 zones then. You mean 3 manifolds all fed via the same Zone Valve, but fitted with 7 actuators in total. (1+2+4)

So, do you mean that the UFH pipes connected to the 3rd manifold are heating up despite the actuators on that manifold not being electrically connected to anything?
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The wiring centre is a HeatMiser UH4


As far as I see, there is one manifold.
The 4 actuators on the right have no feed to them, but still seem to be warming the floor.
That's because they've still got the red mounting clips in place, holding them open. Pull them off the tops and control will be restored

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