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Thread: Boiler setting when only DHW wanted

  1. #1
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    Default Boiler setting when only DHW wanted

    We're told to have DHW set to 55deg to avoid legionella problems. I don't have the ability to measure the output temp of the boiler, and the dial on the W-B boiler isn't much use, but if it's set too low then the DHW will take forever to heat-up. What do people do with their boiler temp setting when CH is off?

  2. #2
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    Quote Originally Posted by DorrisMancer View Post
    We're told to have DHW set to 55deg to avoid legionella problems. I don't have the ability to measure the output temp of the boiler, and the dial on the W-B boiler isn't much use, but if it's set too low then the DHW will take forever to heat-up. What do people do with their boiler temp setting when CH is off?
    Just leave it alone. I donít have a display for boiler temperature, just a knob to turn from low to high. If your DHW temperature is properly set then that is all you need worry about.

  3. #3
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    So how do you decide where to set the boiler temperature control?

    (Am I the only one who reduces the boiler temp "a bit" in the summer, turns it back in the winter, and increases it "a bit" in particularly cold winter periods?)

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    Quote Originally Posted by DorrisMancer View Post
    So how do you decide where to set the boiler temperature control?

    (Am I the only one who reduces the boiler temp "a bit" in the summer, turns it back in the winter, and increases it "a bit" in particularly cold winter periods?)
    I have the DHW temperature set to 55C in the Evohome comtrol panel and leave it there. The boiler temperature I never ever touch. It is set to midway on the knob but no idea what the temperature is at that position.
    Last edited by G4RHL; 30th May 2020 at 11:57 AM.

  5. #5
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    General rule of thumb is to have the boiler set to about 10C higher than the DHW temperature you want. However if you have no way of knowing what your flow temperature is then just leave the dial. There is hardly anything to be achieved by a summer setting. The balance between a high flow but short reheat time or lower flow but longer reheat time is only perfected by trial and error and based on your system and usage.

  6. #6
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    I concur - if your flow temperature is shared between radiators and hot water reheat as it is in my system (no flow temperature "boost" for hot water reheat) then the flow temperature should be a minimum of 10C higher than the set hot water temperature to ensure that it can actually reach the target hot water temp, and in a reasonable length of time.

    I have my hot water at 54C and my summer flow temperature used to be 65C (70 or 75C in winter) however this spring/summer I've just left my flow temperature set to 70C all the time as the load scaling in the beta firmware does a fairly good job of avoiding overshoots in warmer weather without having to manually turn down the flow temperature.

  7. #7
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    I'm now tempted to buy a pipe thermometer - has anyone tried the cheap "clip-on" type, such as https://www.amazon.co.uk/Clip-pipe-t.../dp/B00GYV0L5I ?

  8. #8
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    I have these probes shoved down the foam insulation which wraps around the flow and return pipes above my boiler: https://www.ebay.co.uk/itm/Waterproo...e/283387457858

  9. #9
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    I leave my flow set at around 70oc all year round. Higher flow temp for HW, quicker reheat time.

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