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Discuss Thermostat comes on then immediately goes off in the Underfloor Heating Forum area at UKPlumbersForums.co.uk.

  1. dan85

    dan85 New Member

    [FONT=&quot]Hi, I'm hoping someone can help. I'm in rented accommodation (house built 2 years ago) that has a combi boiler & underfloor heating in the kitchen and living room. Last winter it was working fine, but now the living room thermostat is playing up. When it is set to a high temp, the red light comes on as if to draw heat, but then shuts off - nothing happens with the boiler. The kitchen thermostat is working fine. What could be causing this?[/FONT]

    [FONT=&quot]Here's a video of the thermostat :)[/FONT]
  2. Darren Jackson

    Darren Jackson Plumber GSR

    Hi dan85, If it is a wireless stat then it could simply be a matter of changing the batteries.
  3. dan85

    dan85 New Member

    Thanks Darren, I wish it were that simple. It's a wired thermostat.
  4. Darren Jackson

    Darren Jackson Plumber GSR

    Could you have a faulty actuator on the manifold? When the room thermostat's call for heat, the UFH pump will start and the actuator(s) for the zone in question will open and let water into its circuit's. It takes 3 to 4 minutes until it is fully open. It is
    important that the actuators are fitted tightly onto the return manifold and no loose wires and also check the fuses.
    Last edited: Oct 9, 2016
  5. ShaunCorbs

    ShaunCorbs Trusted Plumber GSR Top Contributor!!

    have you tried calling the manufactures ?

    number : 01455 555930

    also darren it might not be ufh it could be just normal rads off a manifold
  6. leesparkykent

    leesparkykent S. Mod

    The op says he has UFH in the living room and the living room thermostat is playing up.
    • Like Like x 2
  7. ShaunCorbs

    ShaunCorbs Trusted Plumber GSR Top Contributor!!

    didnt see that normally they use a prog room stat for ufh my bad
    • Like Like x 1
  8. leesparkykent

    leesparkykent S. Mod

    Need to get your multimeter out and work through the order of sequence of switching to see what's playing up. If the wiring centre has a PCB it could even be a dry/cracked solder joint.
    Last edited: Oct 9, 2016
  9. Darren Jackson

    Darren Jackson Plumber GSR

    The short video shows the green light comes on and stays on, so I would assume it is calling for heat. I am assuming that the flashing red light is the RF signal?? but am not familiar to this make so could be wrong. I would still check the actuator to the living room at the manifold.
  10. dan85

    dan85 New Member

    The green light is power to the thermostat, the red light is the call for heat.
  11. Uheat – Wojtek

    Uheat – Wojtek Sponsor

    Hi dan85,

    what was the ambient room temperature that time? Was it much less than 21 deg C?
    Do you have a timer installed as well which controls the times of the UFH?

    It's a Maincor branded thermostat but it's made by Heatmiser UK, model called DS-SB.

    You can speak to them directly on 01254 669 090 (press No 2 for technical) and they should be able to tell you what's wrong.

    Hope you will get this sorted.

    All the best,