Selecting Electric Convector Heaters for a 40m2 Apartment: Heating Costs, Sizes & Performance

Hello
My flat is about 40m2, a large room 19m2 (two windows), a small room 8m2 (one window) and a kitchen 9m2 (one window), the apartment is in an old building with thick walls on the 1st floor, windows just replaced with plastic, room height is 2.5m. I am thinking of installing electric convector heaters, but I do not know how to choose this type of device ?? and most importantly (I know that many factors affect it) but I wanted to know more or less what bills may be during the heating season, maybe someone has similar heating at home ?? Let's say we want to keep the temperature in the apartment at about 18-20 degrees, for how long a day would the radiators have to work to heat the apartment to this temperature?

I suggest you take a look at the electricity supply contract and read the power allocation to the premises. Probably there will be 4 kW and single-phase, and then I would try to forget about such heating for the entire premises.

Nobody will tell you that.
In order to be able to calculate the energy demand, empirical data are needed, and the most important of them are the thermal transmittance of the walls and the amount of air exchanged through ventilation.

In normal, insulated buildings, it is assumed to be a minimum of 80W / m2.
In the case of your apartment, the demand may be much higher and remain at the level of 120-180 W / m2
Suppose you will have a demand of 150W / m2.
In the event of the most severe frosts, the energy demand may amount to 40 * 150 = 6000W (6kW) of heating power. The cost of 1kWh is about PLN 0.4.
In the case of non-stop heating with such heaters, the daily cost may amount to 24h * 6kW * PLN 0.4 = PLN 57.60
Of course, assuming the persistence of the greatest frosts that occur in our region. In milder frosts, the cost will be lower.

Unfortunately, electric heating with convection heaters is the most expensive type of heating, and it also requires an electrical installation and a large power allocation.

A cheaper type of electric heating are heaters / storage heaters, which accumulate energy at a cheaper tariff and return this energy at a more expensive tariff. Here, however, we would have to try to get two tariffs.
An interesting solution are dynamic heaters / storage furnaces, which are additionally equipped with an airflow system (fan) and a thermostat that maintains a constant temperature in the rooms. In the case of storage heaters, it is possible to save approx. 30% in relation to convection heating.
Unfortunately, in this case you will have to have an even more powerful electrical installation and an even greater power allocation than with convection heating. Here it will be necessary to invest in a 3-phase installation and a power allocation of approx. 10-12kW.

If you have natural gas in your apartment or the possibility of supplying it, the best solution will be to install a gas boiler and normal heaters. You can buy the cheapest such a boiler for less than PLN 2,000. In this case, you save approx. 50-60% compared to electric heating with convection heaters.

An even cheaper solution will be a coal-fired boiler for eco-pea coal. Here the savings will be on the level of 60-70% in relation to electric heating with convection heaters.

However, the cheapest solution will be a portable wood-burning fireplace. Here, the savings will reach approx. 80-90% in relation to electric convection heating. The costs of heating with coal in the so-called boiler will also be similar. round the clock, i.e. the one to which you pour the coal, you fire, and the automation controls the blow and causes the coal to burn out gradually, maintaining a constant temperature.

Contrary to appearances, many people install 24-hour coal and eco-pea coal boilers in such apartments in old tenement houses. They are usually installed in kitchens or in rooms separated from the kitchen, built-up with plasterboards.
In the case of boilers with a feeder for eco-pea coal, one must take into account a certain drawback related to the noise of the feeder.

Okay, everything is great, however, I mean heating with the lowest possible outlay of money, when it comes to gas heating, nothing of it because there is no such connection in my building (well, unless there are gas stoves of this type from a cylinder), storage heaters are a cost 6-7 thousand, eco-pea coal stoves also around 6 thousand ... Of course, I realize that it is difficult to combine these two things - cheap installation and cheap operation, but I would like to choose something profitable.

Underfloor heating is probably the most economical because the temperature distribution in the room is reversed, the warmest is near the floor and the coolest is under the ceiling, which allows you to lower the room temperature by a few degrees without feeling it, because we are in the lower space of the room, where it is the warmest.
I think that in your case, and with good insulation of walls, ceiling and floor below the heating, you could fit in 2kW, so you do not have to increase the maximum consumption on the contract.
The problem may be the finances for the implementation, especially the possibility of the correct installation of heating without damaging the existing floor covering, which can significantly increase the costs

tomas2323 wrote:

Ok, everything is great, however, I mean heating with the lowest possible amount of money

The cheapest to build and operate will be a portable wood-burning fireplace.

tomas2323 wrote:

(unless there are gas stoves of this type from a cylinder)

Each boiler can be converted into gas from a cylinder, but this energy carrier is very expensive. The cost of operation is similar to the cost of electric heating.
In addition, frequent cylinder replacement will be troublesome, and you may have a problem with other tenants and the building administrator.

tomas2323 wrote:

Accumulation heaters cost 6-7 thousand, stoves for eco-pea coal also around 6 thousand ...

Then buy a boiler without a feeder, approx. 6-8 kW.
The cost of such a boiler is about PLN 1200-1500.
You will also need heaters, some pipes, a vessel and valves, and possibly a pump. Such a boiler has the advantage over other systems that it can be fired with the cheapest fuels: coal, wood. Unfortunately, you have to apply fuel and ash a little.

In sum. You can only choose these solutions:
1. Electric heating with convection heaters or infrared heaters - cheap to build (unless the electrical system needs to be replaced), but very expensive to operate, no work required during operation.
2. Electric heating with storage heaters - expensive to build, slightly cheaper in operation than convectors, no work required during operation.
3. Central heating boiler - expensive to build, cheap to operate, a lot of work during operation.
4. Portable fireplace - cheap to build, cheap to operate, a lot of work during operation.
5. Eco-pea coal boiler - expensive under construction, operating cost slightly higher than in the case of 3 and 4, requires less work during operation than in the case of 3 and 4

Personally, I would suggest you a layout - a portable wood-burning fireplace + electric convection heating or radiators.
When you are at home, you can heat the fireplace. When it comes to burning wood, it has the advantage of leaving a small amount of ash, which means that there is less cleaning and hauling, and also less muck in the apartment. Convection heaters set to minimum heating at night and additional heating of rooms when you get up to work or return home. Such heaters can be easily controlled by room thermostats. Some heaters of this type even have built-in programmable timers and thermostats.
With the cost of the whole, you should be within PLN 2000.

Finally, a note.
Consider installing infrared heaters that hang high on the wall. In relation to convectors:
1. They have a better temperature distribution.
2. Their heating characteristics are similar to underfloor heating, because the heat is given off by all surfaces illuminated by such a radiator.
3. The heat is felt right after such a radiator heats up, before heating the room, because the radiation hitting the clothes and the body causes a feeling of warmth.
4. One disadvantage of this type of heaters is that they illuminate the room at night while sleeping, which may disturb some people.

In the case of a fireplace, it is best to place it in a large room or where you are most often. Ventilation openings will be required for the remaining rooms. By the floor and by the ceiling. The best way to distribute the warm air with the help of fans.