Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

Heating Constantly Running

Hi. I hope you can help!

we have a system boiler that was installed 2 years ago, it’s a simple type that runs when it gets a switched live, no other controls. 

Our house has two heating circuits (upstairs and downstairs) and an indirect hot water cylinder, these are all controlled by 2port valves. There is a circulation pump that appears to be on 24/7. 

The heating circuits have programmable thermostats and the water has a schedule thermostat. 

Nothing has been changed in the past 2 years all all and everything ran fine. 

Recently I noticed the boiler was on constantly and the downstairs heating was not turning off, stat was set at 21C and not calling for heat but we were getting 24/25C. 

I figured that the programmable stat might be at fault so I removed/disconnected this, nothing has changed. I’ve disconnected both programmable stats (physically removed them) and turned off the water schedule and it’s still running?

Ive opened up the wiring centre which is next to the water tank and all wires are connected, nothing loose?

any help appreciated!




  • PC7060
    PC7060 Member Posts: 1,137
    What type of boiler are we talking about? Can you provide pictures of the boiler and the surrounding piping and controls?
  • PC7060
    PC7060 Member Posts: 1,137
    Also, you should power of the boiler if the house is getting dangerously hot or the boiler is over pressuring.
  • AdrianBUK
    AdrianBUK Member Posts: 3

    boiler is a Main system boiler, there are no controls on the boiler you either give it power or not to make it run etc. 

    I’ve been working through this logically and testing as I go. I assumed it was the downstairs programmable stat allowing power through even when turned off but this isn’t the case. 

    The only thing I can put it down to is a fault with the 2-port valve that serves the downstairs circuit, they are Honeywell valves that have a permanent live and switch to open, has anyone ever experienced one of these shorting at all?

  • neilc
    neilc Member Posts: 2,667
    post a picture of the boiler, and we go from there,
    post a picture of the valve,
    it could be stuck open, and calling the boiler, does the manual lever move freely?
    known to beat dead horses
  • AdrianBUK
    AdrianBUK Member Posts: 3

    thanks for your help, as I said above I completely ruled the boiler out as it had no controls at all, on power on/off. 

    The 2-port valve was faulty, it was stuck open and shorting/calling for heat as a result. I’ve replaced it and all is okay. 

    Just need to rewire it all as the way it was done when built is an absolute joke, they must have wasted more time trying to get 4/5wires into a connector than buying something of a suitable size/type to do it properly!

    job for Saturday. 

    Thanks again
  • JakeCK
    JakeCK Member Posts: 1,356