2023-05-21 17:02:00
Heat pump alternative
Heating with the air conditioner – an electrician keeps his house warm for 20 euros a month
Andreas Schmitz with an air conditioner from Mitsubishi
© Andreas Schmid / Youtube
Youtuber Andreas Schmitz wanted to heat his old building in a climate-neutral manner. He didn’t have the money for a heat pump and new radiators. So he installed air conditioning. The DIY alternative to the large heat pump only cost him 6,000 euros.
Technically, the heat pump is a small miracle. It manages to increase the energy fed into it. You put in a kilowatt hour of electricity and get back a multiple of heat energy. What is usually easy in new buildings becomes difficult and expensive in old buildings. It is theoretically possible to heat an uninsulated old building with a heat pump. However, this requires technical compromises that make the otherwise effective technology increasingly inefficient. The culprit is not only the energy escaping from the house, this also happens with gas heating, but a technical dilemma related to the flow and return temperatures and the properties of the refrigerants.
The small heat pump for one room
The Youtuber and electronics nerd Andreas Schmitz therefore came up with an unconventional solution – at least in Germany. He heats his older and uninsulated little house with nothing but small air conditioners. In Spain he wouldn’t use this trick to lure a dog out of the oven, but in Germany the solution is a rarity. The basic situation: His house was built in the early 1970s, the loan is high and so the combination of energetic renovation and conversion of the old oil heating system to a heat pump was not possible.
That didn’t let the energy fox rest. Incidentally, well ahead of Habeck’s energy plans. And of course he knew that the same principle of the new heat pump is also used in well-known household appliances. In fridge and air conditioner. Like many heat pumps, the air conditioners are suitable for dual use: both types of device can cool and heat. Heating with the air conditioning does not work, as the layman might think, with a built-in fan heater, the heat exchanger is also used here. While the fan heater generates a maximum of one kilowatt hour from one kilowatt hour of electricity, the air conditioner conjures up a multiple of heat from the electricity consumed.
Many small split devices
Schmitz has now installed a small split device in every room of his house. Depending on the size, the devices cost between 500 and 1000 euros. A big disadvantage of the solution is that every room is decorated with such a device. This is also the case with radiators, however, and they are even larger. The advantage is that Schmitz avoids the dilemma of the “flow-return temperature drama” mentioned above. No heating system has to be fed with water at 70 degrees or more here. The air conditioners heat and circulate the air. It is sufficient if the outflowing air is above the desired room temperature. The heat exchanger therefore runs in the optimum range.
Many countries have been heating in this way for a long time. In Germany, this has not caught on because of the high electricity prices for private consumers. Financially, things are getting really interesting for Schmitz, because he had previously upgraded the house with photovoltaics and the associated storage system. His system essentially only consumes its own electricity.
High efficiency
The average SCOP efficiency of good devices is between 4.7 and 5.2 – one kWh of electricity produces more than 4.7 kWh of heat. Very good large heat pumps with underfloor heating go a little further, but basically the air conditioners from the hardware store are just as efficient. Incidentally, if a large heat pump is connected to an old heating system that requires high water temperatures, this value will not be achieved.
The costs for a conventional heat pump heating system were not extreme, but they were painful. The pump was supposed to cost 27,000 euros including installation, with – at that time – 7,000 euros in funding. But Schmitz would also have had to replace radiators and at least lay underfloor heating in the living room. Schmitz does not name these costs, but another 25,000 euros would have been added.
Low cost
The air conditioners for this solution together cost 3850 euros without installation. A system for preparing hot water would be included with the heat pump from the installer, and it cost Schmitz another 2,500 euros. Overall, he estimates the costs at 6000 to 7000 euros. You have to keep in mind that he had previously installed and bought a solar system with 11 kWh. But he would have needed that for the “big” heat pump.
Cold and sunny is ideal
In a later video, the hobbyist calculates the heating costs in March 2022. In that month it was still necessary to heat, the temperatures were around 4 to 5 degrees and at the same time the sun was shining. If he hadn’t shut down the system for two days for maintenance, he would have only taken 50 kWh off the grid that month. The costs for heating and other electricity are then between 15 and 20 euros, depending on the electricity tariff.
For the sake of completeness, another special feature should be mentioned: the house had oil heating with radiators when it was bought. On the coldest days, when the air conditioning systems and heat pumps for individual houses lose significantly in efficiency and when there is usually little sunshine, Schmitz switches to oil heating. The oil in the tank has to be used up somehow.
Those
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