My boiler kicks in when the thermostat asks it to, but when my room thermostat asks the boiler to fire up, nothing happens.

My room thermostat clicks on, and lights up so I think it can tell the temperature of the room.

Please can anyone help with my problem?

Boiler: ideal classic lxff
Room thermostat: horstmann HRT 2


2 Answers 2


The room thermostat does not control the boiler directly. Instead, it controls a circulating pump that draws heat from the boiler and delivers it to the radiator(s) in the room. It is the removal of heat that subsequently causes the boiler to fire, when its thermostat indicates that its internal temperature has dropped because of the heat removal.

It sounds like either the circulating pump or the relay that controls it has gone bad and needs to be replaced.

  • 1
    ...or the wire in-between the two.
    – Ecnerwal
    Apr 16, 2015 at 14:35

You say that your boiler kicks in but also that nothing happens, so your description is a little unclear, at least to me. I'm also not sure how many thermostats you have.

If your boiler is firing up when it receives the signal from the thermostat, then you may have a faulty diverter valve. https://www.youtube.com/watch?v=T7UTDtrmcvM

A picture of your pipes / tank / boiler might help.

[I've just noticed how old this question is - doh, why does SO show me such old questions?]

  • 2
    Why such old questions? Because it became active when a new "answer" that was actually a low quality and now deleted question-in-the-answer-space was added to it, then deleted. When you get to some level of rep you can see those, before that they are completely hidden from you. Sometimes the "community bot" bumps an old question, too, but that's not what happened here. You can avoid those by looking at newest rather than active questions.
    – Ecnerwal
    Dec 21, 2023 at 16:01
  • You can also just check the "Asked" text just under the question title and note that is says "8 years... ago". :) That's there on every question.
    – FreeMan
    Dec 21, 2023 at 17:00

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