How to Calculate the Power of Your Radiator and That of Your Boiler

Here is a simple method of calculating the power required per cubic meter of your home. In practice, it’s between 25 W / cubic meter, which is equivalent toan apartment surrounded by neighbors with heating systems, to more than 60 W / cubic meter. In case of poorly insulated glass, the average figure is 40 W / cubic meter.

Step one: Establish your climate zone. Determine the heating requirements for your local heating by locating yourself on the map.
Step two: Set the number of watts per cubic meter required for your home.
Step three: Measure the cubic meters of your room or apartment and multiply them by the number of watts required.

Use the coefficients below, depending on the characteristics of your home region:

Remove 20% for apartments surrounded by neighbors with heating systems.
Remove from 5 to 10% for sunny rooms.
Add 10% for the bathrooms.
Add 5 to 15% for areas with large glass surfaces or north-facing areas.
Add 10% per 500 m of altitude.

The result will be the required power.

Add all of the average power usage of different radiators and the result is the power of the boiler; here is an example  to help you understand better.

 A house of 140 square meters and 2.50 m high ceiling, s with average insulation located in a temperate climate area requires 43 Watts per cubic meter. 140 square meters x 2.50 meters = 350 cubic meters in height x 43 Watts = 15050 Watts.

15050 Watts is the power you need to get with your radiators. Nothing prevents you from exceeding that  energy amount, because the power of your radiators will be the reference for your boiler.

The power of the radiators is announced based on a DELTA operating temperature of 50 ° C. The higher your temperature, the lower will be your yield.

Explanation:

The amount of energy needed to raise the temperature of a fluid is exponential. This means that every degree costs you more than the previous one, so the lowest temperature possible provides more comfort and cost less.

For example: if your house needs 50 kW per day, it’s better to "spread" the 50kw over 24 hours. The boiler lights for one hour at full speed then again for another  hour to evenly distribute the energy while consuming less energy. In brief, the lower the heating temperature, the more you save in C.

The ideal would be to have a regulation system that adapts its power all day as needed. It would be great if you could calibrate the burner so that it delivers the power you need each hour and make minor adjustments to find the most comfortable temperature. When not operational, the boiler will stay below its minimum temperature, and that will lead to substantial savings in the end.

In this case, the delta temperature is the average operating temperature. For example, if the water enters a radiator at 55 ° C and springs at 45 C °, then the delta temperature is 50 ° C.