How Many Heaters?

The level of heating in your home environment must not only deliver the right amount of warmth for your comfort, but also be efficiently delivered.

This can be achieved by giving careful thought to the size and placement of individual electric radiators and including a high degree of control as an integral part of your electric heating system.

Calculations

To calculate how many electric radiators are required, we must first establish how much energy is being lost from the room - the Total Heat Loss.  This is done by multiplying the surface areas of the room by the 'u-values' for each surface and then adding an allowance for heat lost through ventilation.

'U-values' are the amount of heat lost through 1 sqm of material when the outside temperature is 1 degree lower than the inside temperature.

Therefore a room with a u-value of 75 would lose 75w of energy for every 1 degree difference in the internal and external temperature.

As a guide an additional 33% should be allowed for heat lost through ventilation in the room.

The result would be a Total Heat Loss of 75w x 1.33 = 99.75w for every 1 degree difference in the required internal and external temperatures. For ease in calculating the amount of electric heaters required we will round this figure up to 100w.

To ensure sufficient heating on the coldest of days the difference between the minimum outside temperature and the maximum required internal temperature should be calculated and then multiplied by the Total Heat Loss figure.

For example, a minimum outside temperature of -3 degrees and a required temperature of 21 degrees gives a difference of 24 degrees. Multiply the Total Heat Loss of 100w by the temperature difference of 24 = 2400w (2.4kw) of heat required.

You may have the information required to calculate u-values however, in practice it is very difficult to carry out a detailed calculation due to the many types of building materials used over the years, draughts from badly fitted doors & windows, location and aspect.

Although we can arrange detailed surveys and heat calculations, this may not be cost-effective for smaller properties so we suggest using the following 'rule of thumb' guidelines;

New, well insulated property - allow 100w of power per square meter

Older, less well insulated property - allow 130w of power per square meter

Poorly insulated property - allow 160w of power per square meter

Example: Well insulated property with room size 3m x 4m = 12 square meters 12 square meters x 100w = 1200w or 1.2kw heater required.

Please remember these are guide lines only and not accurate heat loss calculations.

If you require any further advice regarding how many electric heaters you require contact one of our team today.