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System pump causing no hot water?

Discussion in 'Plumbing and Central Heating' started by sammy1990, 11 Sep 2014.

  1. sammy1990

    sammy1990

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    Hi all, im getting no hot water at a mates home, they have an old system tank, system boiler etc. Boiler is well old as it has a lottle flame on all the time. But it seems to be running ok, however no hot water. But ive noticed upstairs in a cupboard theres a pump on the pipework, the pump gets red hot and the pipe going onto it is also very hot, 22mm pipe. But the pipe coming out of pump is not hot. Does this mean the pump is faulty and the cause of no hot water? On the pipe going into the pump theres a silver, grey metal box, i think its a two port valve. Not sure what this does but could the be the problem?

    How hard is it to change pump, and are they all the same standard or do you get different types? Its red, with two large bolts on either end
     
  2. TCCHeating

    TCCHeating

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    Lottle flame? Thats a new one on me!

    Does the central heating work?
     
  3. sammy1990

    sammy1990

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    Lol i meant little flame! Not sure if central heating works, but the pipe going into pump gets very hot and pump itself is roasting hot! But pipe coming out of pump is not hot.
     
  4. TCCHeating

    TCCHeating

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    It does sound like it could be the pump but also could be other things, like the motorised valve/valves, programmer, cylinder thermostat, air in system (maybe due to stuck ball valve in header tank or blocked feed).

    You will need a multimeter to diagnose the fault correctly.

    Check that the pump has 230v using a multimeter. If it has the correct voltage but is not spinning then suspect the pump. But make sure you check there is water in the header tank and that the feed is not blocked, as this could have caused the pump to fail in the first place ;)
     
  5. sammy1990

    sammy1990

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    Thanks for reply! Where do i place the multimeter probes on the pump? Sorry if thats a silly question, its just that ive never done this on a pump.

    In regards to the motorised valve, i pull it to the manual position but it simply returns to the auto position. Not sure if that means its ok or its faulty.

    Also just to add, we do get a good flow out of the hot taps, but its simply cold water, its not getting hot. If we had an airlock or a blockage am i correct in assuming we would get no water out of the taps?
     
  6. JohnD

    JohnD

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    An old boiler is likely to be open-vented with an equally old F&E.

    if you bleed the highest radiator in the house, does water squirt out forcefully?

    test that before you do anything else.
     
  7. sammy1990

    sammy1990

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    Thanks John for reply. Il give that a go tomorow. If water does squirt out forcefully, what does that indicate?
     
  8. JohnD

    JohnD

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    it indicates that you have not got the very common problem of old systems, shortage of primary circulating water due to an empty F&E tank or a blocked F&E pipe.
     
  9. DIYnot Local

    DIYnot Local

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