Radiator Power Calculation

Radiator Power Calculation

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The placement of the correct body in power (W) in the space is the condition for the radiators to operate efficiently and economically.

Important factors that affect the heating of the house

1. House insulation

It goes without saying that a well-insulated house (wall and ceiling insulation, aluminum frames, double glazing, etc.) will need less W per square meter than an old house that does not have the same specifications. 

2. Climatic conditions

Other climatic conditions face a house in Parnassus, that is, at a high altitude, compared to a house in a lowland location.

3. Layout and peculiarities of spaces

We must know that the heat diffuses into the space and as a lighter air mass goes towards the roof. It makes sense, then, that a space with a high ceiling height or an internal staircase should be strengthened more than other areas of the house. The same applies to places where there are many openings (windows, windows) and rooms facing north.

How do I calculate the appropriate body in place (W) in space

- With good insulations (dow on the walls, double glazing, etc.) we calculate 100W - 110W per m2
- With bad insulations and single glazing we calculate 130W to 140W per m2
- (Geographical location plays an important role!)
calculation of heater power".


  • Single-sided with 35 Amper (1x35A) safety, "lifts" up to 8KW
  • Three-way with 35 Amper (3x35A) safety, "lifts" up to 24KW


1. Water heater 4 kW

2. Eye rapid 2 kW 

3. Oven 2 kW

4. Laundry 2,5 kW

5. Elect. Broom 1,5 kW


Heaters - Electrical Installation & Installation

- Each body wants separate safety from the panel (excluding low power radiators e.g. 750W).

- The bodies are placed low (10 cm from the floor). Ideal placement position is in the places where there are heat losses, e.g. under the windows, next to balcony door, north walls).


Radiators are very economical in their operation, due to the sensitive electronic thermostat space, if of course the house does not have large losses.

Consumption is equal to 60% of the nominal power of the radiator.

example of convector consumption

Room 3x4=12m2 x 120W=1440W (1500W convex is required)

The 1500W radiator will consume about 1kW an hour.