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Thread: what is this and am i getting ripped off?

  1. #1
    Automated Home Lurker
    Join Date
    Aug 2016

    Default what is this and am i getting ripped off?

    apologies, im new to this so Ive had a quick youtube/google for knowledge.

    I have a heatrae megaflow boiler in a all electric flat

    looking at the boiler it has 2 thermostats elements immersion as above

    last year the boost switch which gives me extra hot water failed so i ignored it, the boost switched on gave extra hot water when needed.

    Last week the 2nd thermostat stopped working, so no hot water, So i called a plumber and paid a 90 call out fee, he had a look and quoted me 700ish parts labour, 2 thermostats or immersions elements thingy and boiler drainage.

    I said id think about it, as i thought it was very expensive . I bought a thermostat online from you tube knowledge for 25.00 quid its a original or oem part.

    I fixed the thermostat in the top spot of the boiler, i believe this controls the boost function.

    But when the hot water gets hot, water squirts out from the thingy and into a open pipe, so I have to switch off the boost and use the hot water to stop the squirt.

    this is the thingy and you can see water in between the ********

    can anyone tell me why hot water come out and if that is normal? if it is not normal then what do I need to do to make it normal,

    Im thinking change the thermostat from the boost and place it in the bottom slot, ?

  2. #2
    Automated Home Jr Member
    Join Date
    Feb 2015


    To fix the water coming out of the pressure release valve, you will need to follow the instructions attached to the side of the cylinder (steps 1-5 in your first image). You will find that you need to do this periodically to replenish the air gap contained within the cylinder.

  3. #3
    Automated Home Jr Member
    Join Date
    Nov 2015


    700 is expensive and 90 callout is robbery.

    Get another quote. should easily get this done for 200-300

    There is a reason you need to be qualified to work on unvented cylinders. They can be very dangerous and should be serviced yearly to check all safety devices are working correctly.

  4. #4
    Automated Home Jr Member
    Join Date
    Dec 2005


    I have to agree with that comment, replacing a thermostat is OK but you really dont want to start doing anything that could disable or bypass the safety features installed by the manufacturer. I had issues with a similar system, this video makes it very clear why you need to give these systems a lot of respect!

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