What gas boiler to take for a 200 sq.m house?

Good afternoon. You have given too little data for a specific answer. From the photograph it is difficult to determine the floor cake, the thickness and material of the walls, the insulation of the roof, the number of windows and which windows are installed.
Also, they did not indicate what concrete floor heating is and what area of ​​the house it covers.

It is roughly considered 10 m2 = 1 kW. adjusted for coefficients:

1. Ceiling height standard 2.5m. In your case, 3 m., Then 3 divided by 2, we get a coefficient equal to 1.2.
2. We take the heat loss coefficient as 1.5 - this indicator corresponds to a poorly insulated house.
3. We calculate the required power of 1 kW * 200 m2 / 10 m2 = 20 kW.
4. Correction for the ceiling height of 20 kW * 1.2 = 24 kW.
5. Add the existing heat loss of 24 kW * 1.5 = 36 kW.

Total minimum power of the boiler you need is 36 kW. Consider, having performed an accurate calculation, the power can change up to 40%. Details and a complete algorithm are specified in this article.

The choice of the boiler is made on the basis of:

1. Power.
2. Type of boiler - single-circuit or double-circuit.
3. A set of solutions, taking into account all the parameters. Efficiency of common gas boilers on average from 80% to 98%. Condensation models with efficiency up to 115% are distinguished.
4. Installation location.

I am sure it will help you this article on our website. It will reveal in detail the advantages and disadvantages, as well as the requirements for most modifications.

When deciding on a boiler model, it is worth taking into account the hot water supply immediately. Combined boilers are economically viable. During the heating period, water is heated from the internal coil through which the coolant passes. The rest of the time it works like a regular electric boiler. Considering that the heating season averages 7 months, this option will be attractive for a private home.