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New Viessmann Vitodens 100-W Magnaclean and cold radiators

Discussion in 'Plumbing and Central Heating' started by iateyoubutler, 9 Mar 2021.

  1. iateyoubutler

    iateyoubutler

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    Evening all :)

    Just (in the last couple of days) had my Vaillant 415 resigned to the bin and a
    Viessmann Vitodens 100-W fitted with a magnaclean filter. I have now found that I have to put the pump up to setting 3 to get the same heat as I had before.......

    The Vaillant was sludged up and knackered but heated the house evenly on any pump setting, but with this new set up unless I have the pump at maximum, half of my radiators get lukewarm at best. Could this be due to extra pressure created by the filter? Nothing else was disturbed so I can`t understand why this is happening?

    If I have to stick with this higher flow rate, are there any pumps that are quiet, as this is bloody noisy?!!

    The boiler is quite happy purring away to itself, I`m just not happy with the way the system is behaving.

    Grateful for any info, thanks all
     
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  3. iateyoubutler

    iateyoubutler

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    Meant to add, the pump is a Grundfos UPS 15-50, and running 7 radiators & a hot water cylinder
     
  4. JohnD

    JohnD

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    You mention sludge. You did have the system cleaned, didn't you?

    Are some of them fully hot and some of them not?

    1) turn off the hot ones

    If the others now heat up

    2) Balance all the radiators.

    This is almost certain to be the case, especially if the system was flushed and not rebalanced afterwards. It is not likely to be the boiler, or the pump, or the filter at fault.
     
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  5. iateyoubutler

    iateyoubutler

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    I get what you say, but when it worked before, why doesn`t it now? Just for info, the rads at the back of the house are red hot, and the ones at the front are not so good. Doesn`t make a lot of sense.....
     
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  7. JohnD

    JohnD

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    Assuming you had the system cleaned of sludge, as you should have done, it will be because the lockshield valves were opened for flushing, and not reset afterwards.

    Balancing is to set the radiators so the hot water circulates evenly though them all, instead of taking the path of least resistance.

    It is not done by opening up the cold ones, but by turning down the hot ones.

    In some cases (for example a small room with a large radiator) you may deliberately choose to reduce the flow so one or more are colder than the others.
     
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  8. iateyoubutler

    iateyoubutler

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    Oh OK, yes the system was cleaned (as it`s 40+ years old now), so maybe he did open up the radiator valves. I didn`t think of that :)

    I would try anything that meant slowing the pump down, as it`s on the other side of my bedroom wall it sounds like a washing machine spinning, but permanently haha!!
     
  9. JohnD

    JohnD

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    if you have TRVs, they will self-adjust to some extent when the hot radiators heat their rooms to target temperature, but that is a slow and imprecise method. You can turn the pump down for tonight.
     
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  10. iateyoubutler

    iateyoubutler

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    Thanks John, I will certainly do that!!
     
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