Greetings, dear professionals and amateur self-builders!
I have been to different parts of Russia and for some reason the craftsmen everywhere use the selection of radiators from the area of the room. If this is Moscow, then the radiators should be 100 W per 1 square meter, if this is Sochi, then such an interesting rule: one section for 2 square meters, in general, each region is famous for its own rules :-))) I confess, very surprises!
In fact, this is the most important mistake that 80% of the masters make. The power of a heating radiator should never be tied to the area of the room, it is calculated exclusively from the area of the enclosing structures. We're not going to put 1500 W radiators in a long narrow corridor 10x1.5 in size, it's stupid!
Let me give you an example! Here is our corridor:
If you look closely, then our corridor loses heat only along short walls, since only they border on the street, and along the long ones it borders on other warm rooms and does not lose through them heat! Is it logical? It is logical! So why arrange a bath with powerful radiators in the corridor?
There is a way that allows you to take into account all these nuances. Agree that rooms with the same area can have different heat losses: there is with one window, there is with two windows, there is with panoramic windows, and there are no windows at all! There is a cold attic and there is an attic! Why shouldn't the features be taken into account?
I don't know who came up with the idea of calculating the heating from the floor area, but the radiators must compensate for all the heat losses that are available in the room, and heat is lost only through the surface of the enclosing structures, and not only through the area floor.
How it's done...
Consider the upper left room on the plan:
For example, let it be the first floor with a ceiling height of 3 m. The street is bordered by 2 walls, one of which has a window with dimensions of 1.5 by 1.5 (2.2 sq.m.).
The rule is: For every 1 sq.m. floor accounts for 4 W, per 1 sq. m. walls and ceilings - 10 W, for each 1 sq. m. windows and entrance doors - 30 W. It is important to add to the obtained data the energy that is spent on heating the volume of air that passes through the ventilation, because we also need to warm it up. 10 W per 1 cube of air is taken into account. That's the whole rule!
Of course, all enclosing structures must comply with the standards, if instead of a brick wall there is a professional sheet, then 10 radiators will not help :-)))
Now, back to the example ...
1) Floor area - 27.5 m2, heat loss 27.5 * 4 =110 watts
2) Wall area without window - 16.5 m2, heat loss 16.5 * 10 =165 watts
3) The area of the wall with a window is 15 m² and minus a window = 12.8 m². Heat loss: 12.8 * 10 = 128 watts
4) Window: 2.2 m², heat loss 2.2 * 30 =66 watts
We summarize: 110 + 165 + 128 + 66 =469 watts
Room volume: 5 * 5.5 * 3 = 82.5 cubic meters, air heating 82.5 * 10 W = 825 watts
Total: 469 + 825 = 1294 W.
The heat loss of our 5x5.5 room is 1294 W, therefore, to heat it, you need a radiator with a power of at least 1.3 kW.
And be sure to pay attention to this:
using the example of steel radiators, almost all manufacturers indicate the power of the radiator at a supply / return temperature of 90/70 ° C (picture above), and this is boiling water. The maximum supply temperature in my house is 55-60 ° C and if I choose a radiator according to this parameter from the manufacturer, then I will never receive the declared power! The maximum I can count on is 700-750 watts instead of the declared 1300 watts.
Consider this please! If you want to select a 1300 W radiator at a flow temperature of 60 ° C, then you need to take at least the one indicated by the green arrow.
And that's all! I really hope that the article was useful to you!
Thanks!