central heating pump problem

Discussion in 'Plumbers' Talk' started by montrano, Mar 17, 2019.

  1. montrano

    montrano New Member

    Hi guys,

    I have a problem which I believe to be the pump, but I thought I'd ask people with more experience before I go and replace it.
    The radiators downstairs are cold and upstairs hot.
    I had a guy in doing a service on the baxi back boiler and he said the pump was fine, that it was probably sludge and wanted £450 to fix it.
    I had a look at the pump and its starting to spin up, then cuts out. The flashing lights give an error code in the manual which just says unstable operation.
    I noticed while the boilers running, theres bubbling in the hot water tank.

    What else can I check to diagnose or fix it. The back boilers was just serviced and is working fine.
  2. Heat

    Heat Well-Known Member

    Sometimes pumps can only work partly and tend to not heat the more difficult parts of circuit - like on drops to downstairs radiators.
    If you have no zone valves, then it could be faulty pump or it could have dirt clogging impeller
  3. Heat

    Heat Well-Known Member

    For to test for sludge I suggest you have one of the rads that are not heating removed and flushed with garden hose and also pipes let run through a hose to see if that rad works
  4. Pollowick

    Pollowick Well-Known Member

    Pump playing up, one floor warm, the other cold ... could well be sludge causing a partial blockage.

    When was te system last drained ? Do you have a magnetic filter fitted?

    Are you reasonable at DIY?
  5. heatyman

    heatyman Well-Known Member

    If pump is running, turn off the isolation valves and remove the head. This will expose the impellor and any contamination. If any is present, clean it out and replace the head. If the downstairs is still cold, close off the upstairs rads and see if the downstairs rads warm up. If the pump still flashes unstable operation, you probably have a faulty unit.

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