Central heating and hot water not working

Discussion in 'Plumbers' Talk' started by Luke-o-saur, Jan 21, 2021.

  1. Luke-o-saur

    Luke-o-saur New Member

    Hi all,

    In these difficult times, we aren’t able to get a plumber to the house, so hoping for a DIY solution.

    We’ve been having problems with our central heating and hot water recently. No heat from radiators, and the hot water gets lukewarm at very best.

    I think we have a pumped(or gravity fed), open vented system with feed and expansion tanks in loft. This is run by our back boiler behind fireplace on ground floor. In the airing cupboard on 1st floor, we have a cylinder tank for hot water storage. With this is the water pump a 3-way motorised valve and an electric box(Honeywell).

    The boiler is firing and we have a warm gas fire going as normal on the ground floor. On the first floor the controller electrics appear to work, as when we turn controller switch on to either central heating or hot water, the pump in airing cupboard starts. This does heat up the feed pipe to the cylinder tank or the feed pipe to the radiators (B or A pipes from 3-way valve). The cylinder and radiators are not even getting warm and the cylinder out flow pipe is staying stone cold. The pump does get quite hot to touch and only starts up on two of its settings, medium and high(2 & 3). There’s no unusual noises anywhere, the water from cold and hot taps are flowing out as normal (just not hot!).

    We’ve tried a few things...
    • Bleeding radiators (maybe not for long enough?)
    • Increasing the thermostat on controller to 30 degrees
    • Increasing the thermostat under the fire/boiler from 3 to 5.
    • Opening the 3-way valve with the manual latch on the motor
    • Bleeding the pump and turning the screw inside (appears to be turning)
    • Checking the loft tanks. Both are full but the header tank is quite dirty.
    Any help or guidance would be greatly appreciated,

    Thanks in advance!
     
  2. jonathanc

    jonathanc Guest

    Does the pump get hotter than the pipe into it and flowing from it?
     
  3. Luke-o-saur

    Luke-o-saur New Member

    The pump might get a little hotter than the pipes, but they are both quite hot.
     
  4. jonathanc

    jonathanc Guest

    It’s hard to guess but it seems like a circulation issue. You could do worse than draining and refilling the system possibly after adding some cleaning agent : sentinel x400
     
    Luke-o-saur likes this.
  5. terrymac

    terrymac Screwfix Select

    See if the pump has water going to it ,sounds like a blocked feed.
    Show pic of the pump and pipework around it ,full height .
     
  6. Luke-o-saur

    Luke-o-saur New Member

    I was thinking that might be an option, thanks for your feedback
     
  7. terrymac

    terrymac Screwfix Select

    Adding any chemical without circulation is going to do absolutely nothing to solve your issue.
     
  8. Luke-o-saur

    Luke-o-saur New Member

    I believe it does, as the pipe to the pump gets hot when on. Also we’ve taken the bleed screw out of the pump and water trickles out.
     
  9. jonathanc

    jonathanc Guest

    well at least I was trying to be helpful and said it was difficult to be sure, rather than just being outright critical
     
  10. terrymac

    terrymac Screwfix Select

    Unfortunately that doesn't prove anything . You have no circulation through rads or coil ,if you did one or both would receive hot water from the boiler that you told us is firing up.
    You need to establish if the pump is spinning ,if it is, a blocked cold feed would be the next thing to rule out.
     
  11. terrymac

    terrymac Screwfix Select

    Not being critical at all Jonathan ,just stating a known fact to save the OP wasting time.
    And you are spot on right ,it is a circulation issue.
     
  12. jonathanc

    jonathanc Guest

    sorry for being touchy. Flushing and cleaning out needed !!!
     
    terrymac likes this.
  13. fred812

    fred812 Active Member

    I'm an amateur so take this with a pinch of salt if you like. I used to have a sticking pump in a previous property. I used to put a block of wood against it to deaden the blow a bit and give it a gentle tap with a 1.5 pound lump hammer. Worked every time until the pump eventually got replaced. Might be worth a try?
     
    Dot99 likes this.
  14. Dot99

    Dot99 Active Member

    Yes give the pump a few light taps as suggested
     
  15. Luke-o-saur

    Luke-o-saur New Member

    I’m not sure how to tell if there’s water running through the pump. I can see the pump is definitely spinning and water trickles out of it with the bleed screw off. So does that mean it could be a blocked cold feed? Thanks for helping
     
  16. Luke-o-saur

    Luke-o-saur New Member

    Yeah tried that! Thanks though
     
  17. terrymac

    terrymac Screwfix Select

    When you removed the bleed screw from the pump ,did you see the pump spinning ,electrically powered ,or did you just turn it's spindle manually.
    I asked for pics of pump and pipework ,but maybe you didn't notice. It would be helpful to see what you have.
    Do you have a strong magnet ??
     
  18. Luke-o-saur

    Luke-o-saur New Member

    The pump was electrically spinning. Sorry, here’s a pic of the pump, pipe work and cylinder. Left pipe out of three-way valve goes to cylinder (so cylinder is on the left hand side to the pump). Hope this helps a little!
     

    Attached Files:

  19. terrymac

    terrymac Screwfix Select

    Do you have a strong magnet ?
    One of the pipes ( not shown in pic) will go from the pump upward to the loft ,that is the feed from the small loft tank . Run a strong magnet all along that pipe from the top of the pump ,up to the ceiling. If that pipe is blocked with magnetite it will attract the magnet .
    If you don't have a magnet ,other avenues can be explored.
     
  20. Mike83

    Mike83 Screwfix Select

    Does seem like a blockage.
    The boiler will fire and you’ll get some movement but you won’t get full circulation.
    If you bleed the system at the highest point and you get no air or water then it will indicate a blocked cold feed.
     
    terrymac likes this.

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