Heat balance

Air at 50°C carries about 10 times more vapour than air at 15°C.

So 90% of the water evaporated from drying clothes by a radiator will condense on a cold wall and cause mould, unless clothes are dried in a ventilated room with the door closed.

A hermetically sealed humid environment at a relative humidity of say 80%RH, with evenly distributed heat is less likely to suffer from condensation and mould, than a dryer environment of say 60%RH, but a temperature difference between the centre of the room and surfaces of 6°C.

Tips to balancing heat

  1. Temperature differences to consider are both across the property and across the course of the day and night.
  2. Maintain an even distribution of heat across the property and minimum nighttime temperatures within about 5°C of the normal temperature.
  3. Modern thermostats such as the Hive and Nest, allow for multiple temperature so that the thermostat is no long just on or off. The cost of maintaining 12°C at night is very little compared to the cost of heating at 18°C.
  4. Radiators work in a series. The first radiator has the potential to be the hottest.
    • Balance heat by turning down the values on the hottest radiators, increasing the valve settings on the coldest radiators.
    • Measure the heat of the radiators with a laser thermometer.
    • Check that radiator doesn’t have air or sludge – use a laser thermometer, see https://youtu.be/sjyEkLwHtTc
  5. Set-up the thermostat, so that it is far from a warm radiator, with a minimum night-time temperature.
  6. Measure the difference between the cold damp or mouldy wall and the thermostat, with a laser thermometer and increase the thermostat temperature accordingly.

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