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Discuss is this how my oil boiler works...Grant Euroflame 90/120 Kitchen/utility boiler in the Oil and Solid Fuel Forum area at

  1. pspec

    pspec New Member

    I have a Grant Euroflame 90/120 Kitchen/utility boiler and I think I’ve worked out how it works.

    The boiler is outside in a shed.

    There’s a standard 3 wire mains power cord going into it (no other wires).

    4 pipes coming out, 2 heats the centre heating, 2 heats the hot water.

    There’s 1 pump in the shed for the centre heating 1 pump in the house for the hot water.

    So as there’s only the power cable going into the oil boiler i think the boiler must only monitor the temperature of the water that’s actually in the boiler. So it must maintain the temp of say 1 litre of water so if the pump is turned on it heats all the water in the system.

    (At first I thought a thermostat inside the house would control the oil boiler but as no wires except the power cable goes into the boiler that can’t be the case…)

    So I’m now concluding that the room thermostat controls the centralheating pump and not the oil boiler and again the thermostat on the combo electric hot water cylinder must control the pump and not the oil boiler.

    Also if all of that’s correct then doesn’t that mean if the oil boiler is constantly heating say that 1 litre of water for when the pump is turned on isn’t that a waste.

    I would of hoped the thermostat would control the oil boiler directly and so it would only heat the required water..

    So how much of that is correct….

  2. PhoenixServices

    PhoenixServices Plumber GSR

    It should all be interlinked to give control over the boiler.
    If the boiler fires up on its own with no demand it's not wired correctly.
  3. DaveyHep

    DaveyHep New Member

    That's how some older systems work. It's as you say...the boiler keeps itself hot then water is drawn off as needed.
    They were designed that way for simplicity when fuel was very cheap.
    You can improve the situation by modifying the controls so that you are only feeding power to the boiler when there is demand. However, this is not a DIY modification.
    Something you can do yourself is check that the insulation on the boiler and especially the pipework is in good order.
  4. SimonG

    SimonG Trusted Plumber

    As above. Old systems relied on boiler stat for control. Swap to S plan, get 2 or 3 estimates.
  5. pspec

    pspec New Member

    thanks... when I get back from my hols ill look into that..

  6. pspec

    pspec New Member

    thanks ... when I get back from my hols I'll look into that..

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