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Discuss Radiators Turning on when should be off in the Central Heating Forum area at

  1. Granty

    Granty New Member

    Hi all, any help appreciated on this issue
    I have done a google search and I see that there could be an issue with the 3 port valve or more uncommon a reverse circulation issue.
    The Boiler model is the I-Mini C30 and the problem seems totally random, it started in the middle of the night once and then earlier my GF turned it off and I think it did stop only for me to nitice it was still on? I turned it off on off again and noticed an hour later it was still on so I pressed the restart button and it went off?

    I probably should add that there has been an issue with the front room rad, I have bled the system 6 or 7 times and the only way that I can get that rad hot is to increase the pressure up to around 3 bar but even then it did stop getting hot after a week or two?
    The boiler was installed about 6 months ago and whilst under the old boiler sometimes this rad had issues at the beginning of the odd winter, bleeding always solved the issue even if it took a few goes, atm i'm just getting water whenever I bleed so wondered if there could be a blockage?
    The reason I mention this is I was wandering if this could be an issue with circulation etc? all rads do get hot except this one atm but this one I had installed separately a long time ago and both ends link to upstairs which whilst I'm not sure I always thought maybe that's why it struggles, with concrete floors and a hallway to cross from the nearest rad I see why it was done like that and guess this is normal but any advice on how to solve this issue would be welcome also.
  2. Granty

    Granty New Member

    Just an update on this, the plumber who fitted the boiler said there is no 3 way valve and is coming out on the weekend, he also advised me on how to sort out the problem rad.
    Of course I still appreciate views on what is causing the issue with the Radiators turning on, there is no timer fitted as I'm saving up for a Nest or similer.
  3. kris

    kris Trusted Plumber GSR

    First things first never put your boiler to 3 bar as all your doing is overpressurising your boiler which will cause more damage than good. Always keep your pressure at 1bar . If the rad isnt heating then you have poor circulation or need the system balanced and bled .. depending how good or bad it was installed then the originall guy coukd have left the system full of air which your slowly removing bit by bit . your boiler will have a diverter valve which is the same as a 3 way valve, but it would only be that if rads were getting hot when hot water taps were ran. I take it the mini c is a combi boiler ?
    If rads are getting hot then it's an issue with your timer or that u haven't set it up right maybe. It maybe an electrical issue as the boilers getting power from somewhere if rads are heating.
    • Like Like x 1
  4. Rob Foster

    Rob Foster Top Contributor!!

    Never Never over pressurise a sealed system. consequences can be expensive and ultimately life threatening. Rob Foster aka centralheatking The way water expands when heated is complicated issue, but essentially for the purpose here it expands .0001 x for every 1c rise in temp, however this is not a straight line and up around higher centralheating temperatures the rate is more significant, obviously near boiling point that is over 200x origional volume. This increase in volume puts undesigned for stress on components and unfortunate consequences, seen the results 1st hand
    Last edited: Jan 12, 2019
  5. Granty

    Granty New Member

    Hi, thanks for your replies/advice, greatly appreciated and regards pressure, duly noted. We had an old boiler that constantly lost pressure with no obvious leak and I guess became complacent with that, we were told to repressurise ourselves via the filling loop that again I was told by other plumbers shouldn't be left on although I think it is quite common that people do?

    Our boiler at present doesn't have a timer as we are planning on installing a nest or similer to work with Alexa.
    Yes Kris it is a combi.
    Today for instance the boiler was on when we came in, yet it is turned to hot water only? When we ran the kids bath the rad symbol on the display went off but as soon as taps turned off it returned. I pressed the restart button and it went off only for 10 mins later it to be on again, I restarted again and it went off for a while until we turned it back on.
    An unexperienced guess from myself would be a fauult with a sensor, is there a frost thermometer or something? As only the onboard computer can be telling it to come on to my mind yet it was 8 degrees outside and I doubt the rads should ever get red hot simply due to frost protection?
    Our plumber is a friend and I told him not urgent so he is coming out when he has a window this week, I just figure it's always worth while to get other opinions but obviously to wake up sweating in a morning and the cost with running the heating when not wanted isn't something we can manage long term.
  6. kris

    kris Trusted Plumber GSR

    I must be missing something but the ideal mini has a C on the screen when a demand for heating is there and a O when no demand , it is a ideal mini 30 is it ?????
  7. Granty

    Granty New Member

    It is the Ideal Mini C30 Kris. See pics.
    , one shows that it's on hot water only but the rad symbol is on, it is currently the same right now, unfortunately I'm having to pull the plug on it just to keep it off, It seems to usually turn off when we turn the switch but then turns itself on randomly?

    The plumber who installed it is a friend of a friend, he never gave us a receipt, I guess he kept it for his tax etc but we're unsure how to act on the warranty other than via him, is that normal? is he responsible for what appears to be a fault with the actual boiler?
    We are waiting on him to come and fix it and he's stacked out atm, so long as there's no danger or more damage to be done it is manageable but of course not ideal ;) long term
    thanks for your help.


    Last edited: Jan 16, 2019
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