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    • Affynity
    • By Affynity 8th Jul 17, 11:52 PM
    • 137Posts
    • 141Thanks
    Affynity
    Combi boiler nightmare
    • #1
    • 8th Jul 17, 11:52 PM
    Combi boiler nightmare 8th Jul 17 at 11:52 PM
    Not sure if anybody can help me out here, who may have had this issue and resolved it somehow.

    I bought a house a month ago and the boiler, serviced by the seller 10/05/17 and allegedly in perfect working order, has this bizarre habit of just heating up water for no reason, and for hours on end.
    When it's in this apparent state of madness, the central heating will not switch on.
    I had a serviceman come check it out, he replaced the diverter, fixed a leak and apparently deactivated its eco mode. But without fail, it will always go back to this bizarre period of killing the central heating to heat up water for nobody's use.

    For reference, its the Baxi Main Eco Combi Boiler. I don't have a thermostat, I've disabled the timer function for selective automatic start up, I've kept the selector switched to hot water and central heating (opposed to hot water only) and I've turned the hot water temperature all the way down to disable intelligent auto pre-heat.

    Literally at my wits end, as I'm wiped out from buying the house and I've only been here since 02/06/17. I'm worried in winter I'm going to have heating that kbky works if the boiler is in a good mood.
    I did try contacting the seller's serviceman but they literally sound ultra dodgy.
Page 1
    • I have spoken
    • By I have spoken 9th Jul 17, 7:20 AM
    • 4,872 Posts
    • 9,564 Thanks
    I have spoken
    • #2
    • 9th Jul 17, 7:20 AM
    • #2
    • 9th Jul 17, 7:20 AM
    Are you sure it's a combi - do you have a HW tank? Could by a faulty HW flow sensor that is triggering. Doesn't the boiler shut down with an over-temp warning?

    Without an external thermostat override, the boiler may not reckon CH is needed in summer temps so won't come on.
    Last edited by I have spoken; 09-07-2017 at 11:25 AM.
    • Browntoa
    • By Browntoa 9th Jul 17, 7:56 AM
    • 31,500 Posts
    • 37,198 Thanks
    Browntoa
    • #3
    • 9th Jul 17, 7:56 AM
    • #3
    • 9th Jul 17, 7:56 AM
    I've got a mega flow hot water tank in an upstairs cupboard , the heating comes on to heat domestic hot water on its own .

    It looks like an immersion and has an option to heat like a traditional one by turning on the electric via a switch next to it
    I'm the Board Guide of the Referrers ,Telephones, Pensions , Shop Don't drop ,over 50's and Discount Code boards which means I'm a volunteer to help them run smoothly and I can move and merge posts there. However, please remember, board guides don't read every post. If you spot an inappropriate or illegal post please report it to forumteam@moneysavingexpert.com Any views are mine and not the official line of MoneySavingExpert.
    • Alex1983
    • By Alex1983 9th Jul 17, 8:32 AM
    • 341 Posts
    • 184 Thanks
    Alex1983
    • #4
    • 9th Jul 17, 8:32 AM
    • #4
    • 9th Jul 17, 8:32 AM
    If you have a mega flow you probably have a system boiler not a combi, have a look under the boiler and see how many pipes are there, I would guess it will be 3 which will make it a system boiler.

    Your fault I would think will have to be a faulty zone valve, which is stuck open causing the hot water to stay on continuously. I know you said you've had a diverter vavle replaced, was that at the boiler or the airing cupboard?
    • timjim
    • By timjim 9th Jul 17, 9:10 AM
    • 42 Posts
    • 23 Thanks
    timjim
    • #5
    • 9th Jul 17, 9:10 AM
    • #5
    • 9th Jul 17, 9:10 AM
    Alex, the OP is not the poster who mentioned the mega flow, but some else who's just added a confusing comment
    • Alex1983
    • By Alex1983 9th Jul 17, 9:54 AM
    • 341 Posts
    • 184 Thanks
    Alex1983
    • #6
    • 9th Jul 17, 9:54 AM
    • #6
    • 9th Jul 17, 9:54 AM
    Ah I see, getting confused by the different posts.

    So when you say it's heating water, is it heating the radiators up. Maybe a sensor that's acting as a frost stat that thinks it's very cold and running heating. If it's not heating the radiators then does it over heat or just cycle on and off, does the dhw light stay on, as suggested maybe hot water switch stuck or sticking intermittently.
    • Affynity
    • By Affynity 9th Jul 17, 11:24 AM
    • 137 Posts
    • 141 Thanks
    Affynity
    • #7
    • 9th Jul 17, 11:24 AM
    • #7
    • 9th Jul 17, 11:24 AM
    Its definitely a combi.
    The service people must have missed something because its literally trying to maintain the hot water temperature constantly, almost like there's a hot water user in the house that I don't know about.
    So, in winter i won't be able to turn on the central heating, in summer, the upstairs is tropical because the boiler is constantly hot
    The system's documentation is useless. It has a reset switch that doesn't seem to do anything. You use it and no sounds, lights or number values seem to change.
    The seller of this house has clearly sold me a dud
    • I have spoken
    • By I have spoken 9th Jul 17, 11:28 AM
    • 4,872 Posts
    • 9,564 Thanks
    I have spoken
    • #8
    • 9th Jul 17, 11:28 AM
    • #8
    • 9th Jul 17, 11:28 AM
    Best get the repair people back in
    • Affynity
    • By Affynity 9th Jul 17, 11:31 AM
    • 137 Posts
    • 141 Thanks
    Affynity
    • #9
    • 9th Jul 17, 11:31 AM
    • #9
    • 9th Jul 17, 11:31 AM
    Ah I see, getting confused by the different posts.

    So when you say it's heating water, is it heating the radiators up. Maybe a sensor that's acting as a frost stat that thinks it's very cold and running heating. If it's not heating the radiators then does it over heat or just cycle on and off, does the dhw light stay on, as suggested maybe hot water switch stuck or sticking intermittently.
    Originally posted by Alex1983
    The selector is constantly on hw and ch, the only other options I have is hw only or off. I turned the hw temperature to minimum, which apparently kills the preheat function.
    If I want the ch on, there's a timer switch that has off/on/selected timed start options. So i leave it off and just turn the ch on when I feel the need

    Currently, all I have is a reading of 62 (I'm assuming thats the temperature), the hw light is lit (nobody is using hot water) and the pressure is 2 bar.

    That's literally my entire function with this boiler. When the hot water light turns off, then I could turn on the heating, but I have no idea how to influence that.
    • I have spoken
    • By I have spoken 9th Jul 17, 11:44 AM
    • 4,872 Posts
    • 9,564 Thanks
    I have spoken
    Guides to using the Baxi - http://www.baxi.co.uk/gas-boilers/discontinued-products/the-baxi-maineco-range-has-been-dicontinued.htm
    • Affynity
    • By Affynity 9th Jul 17, 12:14 PM
    • 137 Posts
    • 141 Thanks
    Affynity
    Never reassuring to see your boiler in the manufacturers obituaries...
    • Alex1983
    • By Alex1983 9th Jul 17, 12:43 PM
    • 341 Posts
    • 184 Thanks
    Alex1983
    Think you'll need to get someone in to repair it. If the hot water light is on then it has to be a stuck flow switch or electrical issue with pcb but that's a lot less likely.
    • southcoastrgi
    • By southcoastrgi 9th Jul 17, 10:58 PM
    • 5,187 Posts
    • 3,012 Thanks
    southcoastrgi
    As above or the Hall effect sensor or you have water passing through a mixer tap or shower
    I'm only here while I wait for Corrie to start.

    You get no BS from me & if I think you are wrong I WILL tell you.
    • Money_Grabber13579
    • By Money_Grabber13579 9th Jul 17, 11:35 PM
    • 2,837 Posts
    • 1,371 Thanks
    Money_Grabber13579
    Whilst not exactly the same fault, or the same boiler, I had an issue where the central heater would come on by itself, even if it wasn't on the timer. Whilst it was possible to override, it turned out it was the electronics which needed replacing, at a not inconsequential cost...
    Northern Ireland club member No 382
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