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Slow Boiler

Discussion in 'Plumbing and Central Heating' started by simps100, 24 Jan 2017.

  1. simps100

    simps100

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    Hi All

    We have a old Netaheat profile boiler with a hot water cylinder.

    Have noticed recently it's got significantly slower heating up hot water / the radiators.

    Say 3/4 months ago I could no problem put the hot water on and have a bath after 30/40 minutes- now after an hour and a hal of it being on its barely enough to run a bath.

    Nothing has changed other than having a smart meter installed so can't see that affecting anything - is there anything common we could look out for what could cause this?

    Thanks

    Marc
     
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  3. JohnD

    JohnD

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    did you have the radiators on in September?
     
  4. simps100

    simps100

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    It did cross my mind it could just be this but then it's not something we ever noticed in previous winters which made me think there could be an issue somewhere
     
  5. JohnD

    JohnD

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    turn the radiators off at the programmer or wall stat; let them go cold. Now turn the HW on at the programmer so it starts to heat the cylinder. Feel the rads. Have any started to warm up?
     
  6. simps100

    simps100

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    Tried that and the radiators don't warm up - I have also noticed the flat never warms up properly anymore as it used to - I didn't think much of it till I realised the hot water was having the same issue too - the weird thing is the boiler fires up and stays on fine it seems - just suddenly significantly slower
     
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  8. jeff the gasman

    jeff the gasman

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    Probable magnetite in the primary flow to cylinder. But then again maybe not.
     
  9. JohnD

    JohnD

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    so the boiler is not delivering as much heat as it used to.

    Perhaps it is not getting fully hot, or perhaps the circulation is poor.

    If you feel the pipes coming out of the boiler, the flow pipe (right hand IIRC) should be too hot to hold, and the Return should be too hot to hold for long. Also feel the pump, and the pipes going into it. How hot are they?

    It is of an age where it probably has sludge and scale in the system, or the pump or valve could be worn out.

    A powerflush would cost some hundreds, but if you are fond of DIY you could start with a chemical clean which may do some good.

    If you check your gas meter readings, do you find that average daily use is less than last winter?
     
  10. ianmcd

    ianmcd

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    if it is the old Netaheat with the Brown Temperature knob these were terrible for breaking you might think it is turned to High but is only set low , if it is that type pull the plastic knob off and turn the control spindle fully clockwise until it stops. then push the knob back on. for all the time it takes it is worth a try
     
  11. simps100

    simps100

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    just abit of an update - today the boiler totally switched off - had to press the reset button on the bottom to make it fire up - its happened very occasionally before maybe once or twice in 3 years so it could be a coincidence.

    Another thing I noticed is the boiler seems to turn off and on an awful lot - the nest app will say the heating and hot water are on (orange) but the boiler won't be lit - the front of it is also very hot to the touch.

    We did have a new kitchen fitted at the start of 2016 and the boiler built in - I thought maybe it was over heating (if that's even possible) because of that - but hat said have only noticed this issue recently and I'm sure would of noticed it in October / November last year.
     
  12. ianmcd

    ianmcd

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    If it is an old style Netaheat and you have it built in as you call it then it requires hi and low level compartment ventillation
     
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