Central Heating randomly coming on

Discussion in 'Engineers' Talk' started by David891, Dec 8, 2019.

  1. David891

    David891 New Member

    Good morning,

    Recently my boiler has started coming on at random times for central heating, heating the radiators up and making the place feel like a sauna. Woke up a few times during the night realising what was happening.

    My thermostat control is a Salus RT300RF and boiler is a Greenstar 25Si Compact Combi Boiler located in the kitchen.

    My thermostat is always set to 17 degrees but the boiler keep firing up the heating even when the thermostat is reading 23 Degrees.

    I have checked the boiler setting and there is no additional on/off times set its all working from the thermostat. I have also noted when the boiler is firing up the central heating the "heating" symbol on the thermostat doesnt display.

    The boiler temperate indicates 32 degrees so it doesnt appear to be frost protection.

    Any ideas what the problem could be?

    Appreciate everyones time.
     
  2. Mike83

    Mike83 Screwfix Select

    When the boiler fires does it run for a while.
    If it does you could quickly remove the receiver from the wall and see if this turns the boiler off.

    The boilers built in frost protection is only to protect the boiler. It shouldn’t heat the radiators.
    An external frost stat would heat the radiators but don’t think you’ll have one if the boilers on the kitchen.
    If the boiler has a built in programmer double check it’s settings.
     
    The Teach likes this.
  3. The Teach

    The Teach Screwfix Select

    Is it known if an external frost thermostat is fitted ? are there any pipes in unheated areas area like garage,loft etc

    Hopefully its just a standard combination installation with no external zone valves or cylinder.

    There is a possibility the boiler diverter valve is letting by and allowing unrequested heated water into the radiators during hot water pre heat,as a test the hot water pre heat can be temporally turned off by selecting the eco setting button. It may already be in eco mode but worth considering.

    When the boiler is firing up with no customer demand,have a look on the lcd display. make a note of whats displayed :)
     
  4. Heat

    Heat Screwfix Select

    Also can be motorised valve faulty, despite random on/offs.
    Isolate power to boiler to temporary prevent heating coming on. There should be a spur switch somewhere
     
  5. BillyT

    BillyT Member

    It may be an idea to change the radio frequency between the thermostat unit and receiver as it may be picking up a signal from a similar unit nearby.
     
  6. Teki

    Teki Screwfix Select

    Which programmer are you using?
     

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