Underfloor hearing and radiators not working independently.

26 Aug 2007
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United Kingdom
Hi All.

I have recently had an extension done and we have UFH on just the new extension, and radiators upstairs etc, in the house we have a nest thermostat and a heatmiser stat for the UFH area. The issue I am having right now is that the nest is the only control for heating the radiators and UFH, the UFH thermostat doesnt seem to have any effect. UFH takes some time to warm up, and when the radiators are very hot upstairs, the UFH is barely warm, so ideally I want the UFH to be able to demand heat independently from the radiators.

There are 2 x 2 zone port valves, and 2 pumps (1 for UFH and another one for radiators), 1 for UFH and I dont know what the other one is for. The UFH is a 2 zone system but connected as one due to the size of the area. The manifold has 4 ports.

The boiler is a 30kw system boiler.

Can someone please explain what is missing/wrong here and what needs to be done to remediate it.

Thanks in advance.
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My first port of call would be to get the original installer back. Sounds like it could be a wiring issue.
Thanks for the reply, I have done a sketch below of how hot water flows in the system, what I cannot do is open up the electrical connections as I wouldnt understand this, the key thing that I had like to understand is that how should this have been wired to achive the goal of the 2 thermostats being able to call for heat independently?

Nest = Rads
Heatmiser = UFH

The nest controls everything right now, the zone valve before the manifold doesnt appear to be doing anything.

Last edited:
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So it’s getting hot to the manifold zone valve, just not after it? I know you don’t understand the electrics, but someone on here may do, and even I might. Are you able to post a photo of manifold zone valve and electrics in the wiring centre?

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