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Discuss Underfloor heating question - Heatmiser in the Underfloor Heating Forum area at UKPlumbersForums.co.uk.

  1. Nth

    Nth New Member

    Hi all

    I have underfloor heating downstairs and radiators, plus two towel radiators upstairs. I have a Heatmiser UH8 and the radiators are connected to the the 5th zone and the towel radiators are connected to the 8th . Now, if I remember rightly from manuals, if you want to hook up a towel radiator, the recommended zone to connect them to is the 8th zone.

    The radiators upstairs, as I said are off the 5th zone and the UH8 has a constant dim lit bulb showing for that zone.

    Here's where my real question is. If I put any of my underfloor heating zones on, they work fine and if the TRVs on the radiators (not towel) are open, they get hot. If I put the towel radiators on, they get hot, but also, the upstairs radiators get hot. If I out just the upstairs radiators on, nothing else gets hot.

    I was told that any under floor heating zone would cause the radiators to heat, but the towel radiators would be separate. This makes sense. There is a thermostat for the radiators upstairs as well one for the towel radiators.

    If the towel radiators coming on causes the radiators to get hot too, why bother putting in another thermostat for the upstairs radiators when any other zone will cause them to get hot? This doesn't make sense to me

    Has anyone come across this before?

  2. Riley

    Riley S. Mod Trusted Plumber GSR Top Contributor!!

    • Like Like x 1
  3. Uheat – Jake

    Uheat – Jake Sponsor

    Are the towel rads and normal rads on the UFH Manifold?
  4. Nth

    Nth New Member

    They're on the UFH manifold I believe, as they don't get red hot like a traditional towel radiator. They're connected to the 8th zone on the UFH-8 too.
  5. Uheat – Jake

    Uheat – Jake Sponsor

    In that case they'd need a actuator placing on each port to control when they open and close. They would need to then be connected to zone 5 of the UH8. This will then allow seperate control of the towel rads.

    If the normal radiators are coming on at the same time as the UFH it seems as if the plumbers haven't installed 2 port motorised valves on each flow circuit to stop back flow. If 2 port valves where installed, when the UFH is calling for heat and the rads aren't the Heating Radiators won't get hot as the 2 port valve won't allow water to flow into the circuit.

    If you want to control the Heating Radiators from the UH8 then you'd need to wire the heating zone valvue to the UH8 zone 8 as the wiring diagram states.

    I've also attached a diagram on how it should've been piped up to control them seperately.


  6. Nth

    Nth New Member

    That's brilliant thanks, that certainly clears a lot up for me.

    The confusion for me was that I was told:

    Any UFH on = normal radiators will get hot.
    I was told that's just how it was installed and it kinda makes sense.

    The bit that even the builder seemed confused over is that the towel rads causing the radiators to get hot. When I asked the plumbers about this, he said it was because the zone (8) that the towel rads are on cause the normal rads to get hot, the same as the UFH does.
  7. Uheat – Jake

    Uheat – Jake Sponsor

    If it's all plumbed together then yes it would all come on together with the rads as well.

    If you want them seperately you'll need to get the plumbers back and get them to change the way they've piped the system up for you.
  8. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    Any pics of the manifold
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