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Central Heating issues - radiators not heating up

Discussion in 'Plumbing and Central Heating' started by FrankCastle, 28 Jan 2019.

  1. FrankCastle


    28 Jan 2019
    Thanks Received:
    United Kingdom

    I live in a 1950's semi. I bought it 5 years ago and it already had a side extension and rear extension. It had a very old boiler, but the rads and hot water worked.

    Almost two years ago - we did some renovation work. We knocked walls out, converted a garage etc etc. As part of the work the boiler (an old potterton) was replaced with a new Vaillant - we also had a new pressurised water tank put in. We also added in a couple of new radiators and moved some others. All the radiators downstairs are new. Some radiators upstairs were also changed - and the ones that weren't changed during this work had been changed when we moved in. Essentially no radiator in the house is older than 5 years and most are only 2 years old.

    When the new boiler was turned on it kept switching itself off and displaying a fault. At first this was perhaps, once a week, then it became once a day, then once an hour etc until it just didn't work at all. The boiler was checked and it was fine.

    The considered thinking was that there was a block somewhere in the flow pipe. The hot water did not work either for months. We had to use the immersion. Then one day, for no reason we could see, the hot water just started to work. It has worked ever since (about a year so far).

    The radiators were all flushed a couple of times and tinkered with. The system was also changed from an open vent to a sealed system. The boiler, was no longer turning itself off but was instead cycling up to about 80 degrees and then switching off. Falling back to 45 and then going up to 80. This happened non stop. Eventually someone said the new boiler was underpowered. It was replaced with another new boiler (a potterton system boiler) that was more powerful. The cycling just happened faster.

    No radiators were getting hot.

    Eventually a (new) heating engineer came - as we threw the builder and his plumber out after nearly a year with no heating.

    Somehow, he got them working - not brilliantly, but working. The boiler stopped cycling and stayed on the whole time. He thinks there could be a problem with the pipes.

    One radiator in the hall now gets piping hot. The others all get very warm.

    However, in the last few days I have noticed that the kitchen radiator seems to only be getting warm at the top. The rest is completely cold. I also noticed the TVR is leaking on that radiator. Not sure if there is any connection.

    None of the radiators (apart from the hall one) seem to be getting that hot anymore.

    Does anyone have any idea what could be the source of these issues?

    Sorry for rambling message. I hope it can be followed!!
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  3. Hi Frank,

    I’m not sure if your sorted now, or if this has been answered elsewhere, seems odd as no replies. Sounds like you could have an issue with the pipes, it could also be that the lock shield valves aren’t open enough. TRVs can stick even from new. 10mm pipes?
  4. ianmcd


    15 Aug 2010
    Thanks Received:
    United Kingdom
    your system needs balancing
    • Like Like x 1
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