“Heating a Large House: Choosing the Right Solution”

Mr. Jiří, before we get to the questions about heating, try to describe your house a little so we can get an idea.

It is a 5+kk bungalow. Usually 4 to 5 people live there. My girlfriend and I have children from our first marriage and we alternate custody, so it depends on how the children “spin”. I say children, but they are actually children already outgrown, all of them are slowly university students.

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How old is the building?

We started building in 2017, it was approved in the winter of 2019.

Did you build yourself or did you build with a company?

I made some things myself, but a lot of things were made for me by various craftsmen and companies, depending on what was needed and what I asked. Rather than self-help, I would say that we built with help. But you always have to organize it somehow.

How big is your facility?

The built-up area of ​​the house is 277 m² a living area of ​​some 220 m². The total area includes a double garage, which is also heated to a lower temperature.

This is a relatively large house and it is difficult to heat it. Do you know its heat loss? I assume it will be a passive or low-energy house…

I might even find the energy label that I had for the building permit application. I suspect so according to the label, the cost of heating the bungalow is 44 kWh/m² in a year. Of course, I tried, regardless of the project, to make the house as insulated as possible. This means that I chose materials and a greater thickness of insulation than was the case in the project, in order to keep operating costs as low as possible.

How did you decide how to heat such a large house?

I wasn’t looking for a cheap solution. I was looking for a solution that would meet my criteria. The first condition was that the system should be convenient. No adding to the boiler. The second condition was in line with my vision of connecting this system to the photovoltaic power plant on the house, which I had already planned at the time. I reasoned that if it was at all possible, I would have only one medium in the house, i.e. electricity. Even though there is a new gas connection at the property, I thought that I would not deal with the gas boiler unless it was necessary. Rather, I was thinking about an electric boiler in combination with hot water floor heating. This meant that I would have a fireplace or a fireplace insert for it.

Gas boilers can be purchased in various price categories. For a better idea of ​​the options and prices, you can look at comparison of the best-selling models.

So how did you go about your search?

We investigated the possibilities and put together the pros and cons. In total, we were in about three companies that do heating. We had heat losses calculated and a heating method suggested. One company suggested to us that they would make both hot water underfloor heating and a combination with radiators. But this option was incredibly expensive. We abandoned the idea of ​​a combination of radiators and underfloor heating and decided to only have underfloor heating in the house. As the main source, an electric boiler seemed less suitable to us, but due to the energy label, it had to be combined with a fireplace stove or a fireplace insert. However, we eventually replaced the fireplace insert with photovoltaics.

Have you considered a heat pump?

I thought a lot about him at the time, but there were a lot of things that bothered me. The first was the purchase price. In addition, at that time there were no subsidies for heat pumps in new buildings, but I would not elaborate on that here. I did mention that I wasn’t looking for a cheap solution, but whether you pay 30,000 for an electric boiler or 250,000 for a pump makes a difference. Yes, it is necessary to think about the fact that the pump has a heating factor, but even so it is an incredibly expensive option economically. Not to mention that the pump needs service over time, and it’s not free either.

But not to speak only against, I liked the idea of ​​using a heat pump to cool the house. However, this option entailed the necessity to make a second pipe circuit in the floor, which meant additional investment. So we looked further. Nowadays, for example, they can solve this problem with one pipeline – I don’t know. Everything is constantly moving forward and has some development.

For a better idea, you can make a price comparison here electric boilers a heat pumps.

To move on, which heating option did you choose in the end?

By chance, I discovered floor heating foils on the Internet. It seemed like an interesting system, so I went to check it out. Then I also got some references, found out how it is regulated, etc. With the fact that they would do it with anhydrite as well. I liked this but struggled a bit with the price. Then I found out that there are also wires that go into the floor. I also had an offer made for them, and it was for 170,000. That price/performance difference isn’t as much of a price difference.

Why did you finally change your decision and go back to floor foils?

Because of completely different characteristics. The heat transfer from the foils is over the entire surface, and therefore faster than a cable that is coiled like a snake. The second thing is also logical, the snake (resistance wire) must not be placed under the furniture so that the area cools and does not overheat. Which is limiting. We have three children, we arrange a room for each of them when they are small, but when they grow up, they rearrange it to their own taste, but you know that. Likewise, we didn’t know what kind of furniture we would have and where exactly it would be. That snake resistance wire is just limiting in this.

Now to sum it up, how do you heat the house, heat the water and what technologies do you have at home?

We have radiant heating foils in the floor throughout the house. We heat the water in a classic boiler and I had a photovoltaic hybrid power plant with flashlights installed on the roof. It produces approx. 8 MWh per year.

If I count correctly, you have 4 heating seasons. Would you know what your heating costs are during that time?

When I installed the system, I wanted a secondary electricity meter to know exactly how much I was burning. Of course, there are concerns that electric heating is very expensive. People think that if they have a family home and have heating, then heating is the biggest expense of the house. It may or may not be. It depends on how the house is built, how many people are in it and how it is managed. For me, it works out that a third of the costs of running my house is made up of heating. The second third is heating domestic water. The last third is my household operation (washing machine, dryer, dishwasher, computers, lighting and other normal operation, such as cooking).

So, thanks to the secondary electricity meter, you know exactly how much you have heated up in a year?

After moving in, the house wasn’t perfectly dry yet, so we heated a lot. When the frosts hit, I looked and the photovoltaic application showed me that I had consumed maybe 80-90 kWh per day. I thought it was terrible that we wouldn’t pay. However, the first season passed and the consumption on the meter for that heating season was somewhere around 6.5 MWh. The photovoltaics produced something for me (it produced less than 8 MW), there were some surpluses that went into the grid. The total billed consumption after deducting photovoltaics was 11.5 MW. Photovoltaics will make one third, I pay two thirds. However, I would like to point out that we have a slightly higher consumption of water. It was 210 cubic meters per year, which also makes a significant part of the energy.

So it is true that in a bungalow with a living area of ​​220 m² will you spend about 40 thousand crowns in a year?

Yes, every heating season we got under 40,000 crowns for electricity, even with the heating of domestic hot water for the whole year. I can easily prove it with a bill. I monitor my consumption regularly every month and write it down. My electricity is now fixed until the end of September this year. Purely for heating, our consumption for 4 heating seasons averages around 6.5 MW/year. It is then 11.5 MWh for the whole house. Everyone can calculate the price for heating from this value.

The transition to a heat pump was very expensive for the couple

Do you think this type of heating is more economical than others?

If I compare, for example, the input costs compared to an air-to-water heat pump, I am at less than half. I don’t have to deal with service either, nothing. Those foils in the floor last for decades and their effectiveness does not change. I won’t have to change anything in 15-20 years. The only limiting factor is the price of electricity, but that’s something you can’t influence even with a pump. So the savings in tens of thousands is here.

You talked about photovoltaics. Do you have it connected to underfloor heating or do you use it to heat water?

Whatever turns on uses that energy. Of course, when winter is needed, photovoltaics will produce the minimum of what you need. From what I have evaluated, it is rather used for heating water during the summer and for the normal operation of the house.

How many degrees do you heat the interior?

The bathrooms are set at 24.5 to 25°C and the children’s room is at 23°C. I have the corridor, which makes up a large part, at 22.5 °C. The living room is just like the hallway. We have a bedroom at 19 or 20 °C. The average temperature in the entire house is thus about 22.5 °C.

How do you evaluate your choice in retrospect?

As for the user rating, it is simply handled in the application. You click and everything is easily set up. Of course, it should be taken into account that this is underfloor heating. If you add or subtract one or two degrees, it has some inertia. It doesn’t regulate very quickly.

Can you think of anything else in conclusion?

What is generally important for this system is the understanding that it is necessary to take such measures so that the house has as little heat loss as possible. This also applies to heat pumps, it is not suitable everywhere. It is not the fault of the heating, but of the space and environment. It is necessary to choose the right source for the house.