The main theme of the article is the trend of converting air conditioners into heat pumps - a broad and multifaceted topic. We'll try to delve into it as comprehensively as possible, considering most of its aspects. We'll focus on the air-to-water heat pump specifically, which is intended to heat homes with traditional heating systems (i.e., water-based - using radiators or even better, underfloor heating). The article will carry elements of a DIY (Do It Yourself) approach, but it's not necessarily an attempt to discourage "professional" heat pump solutions. Instead, we aim to familiarize the reader with the topic.
Choosing the right heat exchanger for the heat pump converted from an air conditioner requires attention to several aspects to avoid its leakage - because it's essential to know that freon heated to certain temperatures generates high pressure inside the system, which could rupture the heat exchanger. Therefore:
✅ The simple answer is that your heat pump converted from the air conditioner won't work - there's no other way to transfer heat to the system. Alternatively, if the heat exchanger is too small, it will be undersized only to a small extent - it will function, but at half capacity, and there won't be any real benefit from it. Additionally, your heat pump will frequently shut down due to lack of heat transfer, causing the entire system to operate very inefficiently and consume significant amounts of energy.
✅ In reality, a professional heat pump doesn't differ much from these types of conversions in terms of the basic idea. They are also outdoor units with fans equipped with an appropriate condenser (heat exchanger) transferring heat to a fluid. This is how an air-to-water heat pump works - and if our DIY heat pump converted from an air conditioner is meticulously executed, it's not necessarily unprofessional.
☑️ However, a "professional" heat pump additionally features a range of sensors and automated operation, enriched with modules like Wi-Fi - providing various possibilities for monitoring the performance of the entire system. This is certainly an advantage, sometimes invaluable. It's extremely easy to control - often from our smartphone.
At this point, we must decide whether these advantages are worth the price difference - because the difference in heat production efficiency isn't always significant. Of course, it's assumed that the advantages will always favor professional ready-made solutions, as reputable companies producing heat pumps continually seek new technical solutions to optimize the heating process and reduce energy consumption. We can't expect the same from air conditioners - however, differences in efficiency are not at least striking at the moment.
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AC - commonly used abbreviation for Air-Conditioner or Air-Conditioning
F-gas - fluorinated greenhouse gases, used as refrigerants in air conditioners, refrigerators, freezers, heat pumps (see: freon), they may also appear in the context of the topic, it's worth noting that qualifications are required for their use.
Freon - refrigerant gas used in air conditioning - essentially one of its common names, specialists actually prefer to use the term refrigerant. In reality, freon is a trade name created by some French company that patented it (the word has entered common usage in some languages). It has the ability to absorb heat from the surroundings, even at below-zero temperatures - which is why it's used in air conditioners, heat pumps, and even refrigerators.
Inverter in air conditioning - a device used in newer air conditioners that enables smooth regulation of the compressor's speed, influencing the adjustment of energy consumption and power used to meet the needs.
Inverter air conditioner - a type of air conditioning unit that uses an inverter to regulate the compressor's speed, thereby having the ability to modulate power and energy consumption according to needs. It's definitely more efficient and economical to use, as well as more convenient than older versions without inverters.
Heat pump condenser - a component of the heat pump system that converts the refrigerant from a gaseous (volatile) phase to a liquid phase by transferring heat to another medium or to the surroundings. In our case, we want the heat from the heated refrigerant from the air conditioner to go to water - and into our heating system. Plate heat exchangers are commonly used as condensers in DIY projects.
HP - commonly used abbreviation for Heat Pump
Outdoor AC unit - air conditioning unit located outside the building (in the case of air-to-water devices), equipped with a fan, etc.
Outdoor HC unit - the same as above, but reffering to heat pumps.
Oversizing the heat exchanger / condenser - selecting a heat exchanger designed to operate as a condenser with slightly more power than the power of a given air conditioning unit. This practice is recommended for certainty and to avoid the potential consequences of miscalculations.
Refrigerant - one of the gases used in air conditioners and heat pumps, there are many types such as R404, R407c, R410a, or R32; (see entry: freon)
Refrigerant heat exchanger - a type of heat exchanger, in this case, a plate heat exchanger, with several characteristic features that adapt it for use with refrigerants, cooling agents, etc. The main concern is its resistance to pressures above 40 bar.
R407c, R410a, R404, R290, R32 and similar - the names of specific refrigerant gases used in HP and AC. Of course every one from them has a bit different capacity and parameters. The newest tendency is to replace the older ones with R290 or R32. Especially R32 is considered to be most effective and in the same time has potentially the lowest impact on the environment. More information about the refrigerants you can find on our blog.
Undersizing of a heat exchanger - what does it mean in practice?
Oversizing the heat exchanger - what is it for?
What is the production process of brazed plate heat exchangers?
How to choose a heat exchanger for a gas boiler?
How to properly connect a Nordic Tec plate heat exchanger? Can I reverse the flow directions?
History of plate heat exchangers
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