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Nov 19, 2021
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Knaresborough
Member Type
DIY or Homeowner
Hello. I am here for some advice please.

We have a water underfloor heating system in our house and have recently had some issues with one of the zones seeming to overheat with the heat still being sent despite the thermostat not sending demand or even being on an all. These are all new thermostats which were replaced a few weeks ago and that is when the problem started.

We called a very reputable heating engineer who has now been 4 times and unfortunately still doesn't know what is wrong. He said it could be an issue with the actuator, so has replaced the actuator - the original type of actuator was no longer available (Behr Thermot-Tronik X7 592 70 10, 230V, 50-60 Hz, 3W F4, D70806). It has been replaced it with a new Mohlenhoff actuator.

The Mohlenhoff actuator appears to be getting very hot during day to day use. Is this usual? It is not too hot to touch but is pretty warm. Our other 2 actuators (still the original type) are not hot.

The engineer is proposing to come back again this week and is bringing an electrician with him but please could anyone help advise on (a) if there is any way to cut off the supply to the zone in question whilst we wait for this, as it's very hot, and (b) what might cause a zone to be constantly heating up, especially if the actuator is getting hot in the process.

I am pondering if we should get a new engineer for a second opinion but there aren't loads of options.

Thank you in advance for any advice!
 
To stop that zone overheating temporarily just remove the actuator If your competent with electrics unwired it .
Maybe check that the pin under the head is moving freely.
Anyone competent with a multimeter should be able to sort it.
 
some actuators will screw down see if yours does BUT do not force it, or if you know whats what shut the flow down.
 

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