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UFH Pump Repair/replacement

headscratcher
headscratcher Member Posts: 2
in Strictly Steam
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Hi there - would appreciate some advice. My pump (Grundfos UPS3) has stopped working. The impellor seems to be movely freely but the unit is still showing a red light. I have now disconnected the power supply and now wondering how I can remove this. There are no isolation valves above & below the pump. Do I need to drain the entire system to do this? This is a ground floor supply circuit serving UFH with radiators upstairs. The radiators upstairs don't have any drain valves on them. Can I isolate the boiler simply by turning it off and closing the manifold valves and water supply? I would be grateful for any comments and advice. Many thanks

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Comments

  • Kaos
    Kaos Member Posts: 301
    edited November 2024

    Sometimes you can do a live replacement if you are quick. Shut off the water feed, boiler, the manifold and release the system pressure. Get the new pump ready to slide in as soon as the old one comes out. Will make a bit of a mess, less of an issue if there is a floor drain. If there are TRVs on the rads above, it will help to close them as it will make water harder to drain.

    You'll still have to bleed the whole system after the swap though.

    headscratcher
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 16,702

    And if you attempt to do it live (which I don't recommend) make sure the water is cold.

    headscratcher
  • headscratcher
    headscratcher Member Posts: 2

    Thanks both - can you clarify what you mean by releasing the system pressure please?

  • Kaos
    Kaos Member Posts: 301
    edited November 2024

    Most heating systems are pressurized to around 1bar. When you shut off the feed water, this pressure is still there.

    Typically there is either a drain or a vent you can open near the boiler to release this pressure. Make sure to connect a hose and run it to a drain when you do it.

    I don't see one on your boiler in the pictures which is strange. You can use the drain at the end of your floor heat manifold.

    P.S. Don't blame me if this makes a mess. I've done heater element replacements on water heaters like this before without issues. The key is not to have any other opening to let air into your system except what you are removing, so make sure any auto air vents are capped.

    headscratcher

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