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Powermax 155x not firing for central heating

Discussion in 'Plumbing and Central Heating' started by muffking, 15 Mar 2018.

  1. muffking

    muffking

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    Hi guys.
    Just replaced a radiator in my bathroom and now my Powermax 155x won't fire up for central heating. Hot water works ok, but the only thing I did to the boiler was drain down, re-presurise the expansion vessel and refill the system.
    It appears that the upper left pump in the photo is humming and getting hot. It has power to the terminals when the boiler calls for central heating. Could I have upset it by draining it down?

    [​IMG]
     
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  3. hertsboilers

    hertsboilers

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    Air around the pump, or pump jammed.
     
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  4. rochdalegas

    rochdalegas

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    Could just be air. Have you tried bleeding the pump.
     
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  5. Sounds like the heating pump has seized,usually it can be restarted by removing the centre screw (water will drip or flood out) and turning the impeller with a smaller screwdriver.
    As the store is up to temp (you say you have hw) any water issuing from the heating pump centre screw will be F xxxxx Boiling. so either leave it to cool or be brave :!:.
    recommend the pump is changed thou :idea:

    Not many of them powermax boilers left (y)

    edit,did you check for 240 ish volts at the pump during a call for ch ?
     
  6. muffking

    muffking

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    Thanks guys.
    I'll let it cool down overnight and remove the screw in the morning as the pump has 240v when the boiler calls for ch.

    To bleed the pump do I just let the water out from the screw? And do I need to depressurise the system first?
     
  7. No need to depressurise as long as only a trickle of water when removing centre screw :)

    This guy fixes his pump which what looks like a wood chisel,pure diy (n)
     
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  8. muffking

    muffking

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    Just braved it this evening as it's cold.
    I wouldn't say that the pump turns freely when using a small flat blade screwdriver and only a very small amount of water came out from the centre screw.
    I'm a bit concerned that the burner doesn't come on when there is a call for central heating. Is this linked to the pump or could I be chasing a red herring?
     
  9. the burner will fire when the store water is depleted or getting low,sounds like the pump is faulty.

    Any heat in the rads yet ?
     
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  11. muffking

    muffking

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    Thanks.
    The burner fires for the hot water as it's set to keep the water hot all day, but it just won't fire for the central heating. I didn't know if that was caused by the pump not spinning?
    Just not sure what to do as it was working fine until I drained it down and then filled back up again after fitting the new rad.
     
  12. Can you turn the impeller with power to the pump,it may just restart.

    is your hw actually hot when being drawn off at a tap ?
     
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  13. muffking

    muffking

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    Good call. Just tried that and eventually it started spinning. Feels laboured and slow though. Still no burner kicking in.

    The taps run hot ok and the burner kicks in to heat the tank.

    It's definitely looking like the ch pump is seizing up, although I don't know how that stops the burner from heating the water for the rads?
     
  14. on your unique appliance,the heated store of water inside the boiler will be pumped into the radiators or plate heat exchanger.if its not being pumped out the store will stay very hot and satisfy the boiler thermostat.

    The boiler needs to pump out the heated store water to either the radiators or plate heat exch then the boiler thermostat will respond and light the burner again :cautious:

    your plate heat exchanger pump is working but your central heating pump seems faulty,its a powermax after all (y)
     
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  15. rochdalegas

    rochdalegas

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    Try squirting a bit of washing up liquid in the pump with the nut removed. Can help free things up.

    We used to have a fair few of these on a contact I worked on. if its never been serviced over the years just a heads up that the flues had a nasty habit of rotting worth checking/ getting someone in to check.

    Finally if you go down the route of changing pump drain down to do it or change pump valves they will leak as soon as you touch them
     
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  16. muffking

    muffking

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    Thanks. Boiler pressure had dropped to almost zero overnight, so I had to pump air back in the vessel again and refill the system back up to pressure. Tried washing up liquid in the pump which seems to have helped as the impeller seems to move more freely, but it's still not firing for central heating and I seem to be losing pressure when left off for a while.

    If it helps, I'm hearing lots of bubbling water sounds when I call for central heating and the pumps starts. Could it be that I just have a system full of air?
     
  17. muffking

    muffking

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    We now have progress.
    After repressurising the system for the 3rd time the burner is now kicking in when I call for central heating. There is a ton of gurgling noises coming from the boiler, pipework and rads, but I'm now in the process of running round continuously bleeding the rads.

    When refilling the system do I need to let the boiler cool before introducing cold water to build the pressure back up?
     
    Last edited: 16 Mar 2018
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