Can you heat the water with the central heating drained?

Discussion in 'Plumbers' Talk' started by joethediyplumber, Aug 7, 2021.

  1. joethediyplumber

    joethediyplumber New Member

    I have a closed central heating system and I'm not sure how it works, but to heat the water it uses the boiler and then stores the heated water in a tank.
    I want to spend a few days replacing radiators and will need to drain the system down, but I need the hot water to keep running for showers etc. Is it possible to keep the boiler on manually turn the hot water on, whilst having the central heating off and drained?
     
  2. dcox

    dcox Screwfix Select

    If you've got a hot water cylinder - vented or unvented - you've probably got an electric immersion heater than can be used to heat your water while the boiler is out of action. Look on your cylinder for something that looks a bit like an aerosol can cap with a flex coming from it.
     
  3. Oli_london

    Oli_london New Member

    Do you have a combi boiler?
     
  4. joethediyplumber

    joethediyplumber New Member

    I had a look at the cylinder and have attached a photo. It is a ThermaQ Indirect Unvented. Looks like there is a heating element going in the side. So, I guess when I switch the heating on, using the remote thermostat device, is it heating the water using the element or the boiler - how do I tell? If it heats using the element then I guess it is safe to have a drained system and keep the water on (?)

    https://photos.app.goo.gl/FWBW6jZzG1ih2cwP7
    [​IMG]
    [​IMG]
     
  5. dcox

    dcox Screwfix Select

    Yes, that’s right. It’s the white switch on the floor. It will have a built in thermostat so will turn itself off when the water is up to temperature.
     
  6. joethediyplumber

    joethediyplumber New Member

    ok, so I was sure that the boiler came on when I switched the Hot Water on from the remote switch. So, how does this work - does the boiler heat the water or the element, or both?
     
  7. dcox

    dcox Screwfix Select

    That’s an electric immersion heater. Independent from the boiler and heats the water a bit like a kettle element.

    If you’re using the boiler: Inside the cylinder is a coil of pipe that’s heated by hot water from the boiler and transfers heat to the water inside the cylinder.
     
  8. joethediyplumber

    joethediyplumber New Member

    ok, thanks for the explanation :) .... so I guess that the immersion heater is on all the time and that the remote control for the system doesn't even control the hot water (?)
     
  9. dcox

    dcox Screwfix Select

    The immersion should normally be off if the boiler is capable of heating the hot water. It’s more economical to do it that way.
     

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