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Air-to-air heat pumps – what should I know?

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Air-to-air heat pumps – what should I know?

An air-source heat pump is an environmentally friendly solution for heating a house or apartment by using energy from the outside air and electricity. As a reversible device, it not only allows efficient heating, but can also operate in cooling mode, thus providing savings in operation and high comfort of use.

Why choose to install an air-to-air heat pump?

The decision to invest in an air-source heat pump comes with numerous benefits – both economic and functional.

The most important advantages of air heat pumps are:

·        provide both energy-efficient heating in winter and efficient air conditioning in summer.

·        are an ideal replacement for old heating systems, allowing you to obtain an efficient and economical source of heat in your home and apartment.

·        are distinguished by their high energy efficiency class: A++ in cooling mode and A++ in heating mode, which directly translates into lower heating costs.

·        compared to air-to-water and ground-to-water heat pumps, are cheaper and simpler to install, and do not require additional ground drilling and drainage installation.

·        KAISAI heat pumps are powered by 75% energy extracted from the air and only 25% electricity, making them an ecological and economical solution for both houses and apartments.

Perfect solution for space heating in low outdoor temperatures.

Thanks to advanced technological solutions, the efficiency of air-to-air heat pumps remains high even at very low outdoor temperatures. KAISAI’s available line of KAISAI HOT and KAISAI PRO HEAT units, dedicated especially to the function of heating, is adapted for efficient and energy-efficient operation in heating mode at outdoor temperatures as low as -25 ° C.

What are the costs of an air-to-air heat pump?

Heat pumps contribute greatly to a significant reduction in the cost of operating a home. Also, purchase and installation costs are lower than for other heating systems. When choosing a heat source for your house or apartment, it is worth bearing in mind that the air-to-air pump mostly uses the energy contained in the outside air, and the high energy class of the device allows you to further reduce the level of electricity consumption, which makes the investment in an air-to-air heat pump prove to be very attractive economically.

Feel free to learn more about KAISAI air-to-air heat pumps:

·        KAISAI HOT series

·        KAISAI PRO HEAT series

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WHAT KIND OF AIR CONDITIONING SHOULD BE INSTALLED, DEPENDING ON THE FACILITY?

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WHAT KIND OF AIR CONDITIONING SHOULD BE INSTALLED, DEPENDING ON THE FACILITY?

The wide range of the currently available air-conditioning systems makes it necessary to consider which devices will be suitable for particular facilities, before you actually purchase them. Different types of air conditioner will be suitable for cooling and heating the house, but completely different ones for an office building or a shopping mall.

In apartments, people usually opt for the split-type stationary air conditioner with an indoor unit mounted on the wall. This model is easy to use, quiet, and its installation does not involve significant interference in the room’s structure. In terms of purchase costs, it is also favourable compared to other types of equipment. For more-demanding and aesthetically pleasing interiors, it is possible to use cassette or duct air conditioners, embedded in a suspended ceiling.

If we do not want to or cannot install stationary units, your only choice is portable air conditioners.

On the other hand, central VRF air-conditioning systems, consisting of one unit and up to several-dozen indoor units, are more frequently used in offices or retail and public-utility facilities. The units are usually placed on the roof of a building, while the cooling systems and the indoor units are installed inside the rooms. They are predominantly cassette, duct, or ceiling units, mounted inside or directly below suspended ceilings.

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SELECTING THE CORRECT TYPE OF AIR CONDITIONING

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SELECTING THE CORRECT TYPE OF AIR CONDITIONING

Selecting the correct type and performance characteristics of an air conditioner is a prerequisite for its successful operation. The process of selecting the air conditioner based on the type of facility has been discussed separately. However, it is best to entrust the selection of equipment, in terms of its performance, to specialists with the appropriate knowledge and experience in this field.

However, there are a number of general recommendations and indicators which allow users to pre-define the required power of the device themselves. The most-important parameter is the cubic capacity of the air-conditioned room. It is considered that the required cooling capacity in standard rooms with a height of about 3m is approximately 40 W/m3.

However, there are exceptions to this assumption. This value can change if, for example, there is a particularly large area of windows in the room, which also face south or west, the walls of the room have poor thermal insulation, or there is a roof directly above the air-conditioned room. The number of people present in the air-conditioned room is also important, and whether there is any equipment generating additional heat, e.g. computers, monitors or refrigerators.

It is worth remembering that the factor increasing the required cooling capacity of an air conditioner is the presence of mechanical ventilation in the room, which should be taken into account when selecting the appropriate air conditioning system.

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THE OPERATING PRINCIPLES OF SPLIT-TYPE AIR CONDITIONING SYSTEMS

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THE OPERATING PRINCIPLES OF SPLIT-TYPE AIR CONDITIONING SYSTEMS

Each split-type air conditioner is comprised of two components – an outdoor unit and an indoor unit, the latter of which, depending on the applied method of installation, can be wall-mounted, floor-standing, duct (installed inside the suspended ceiling space and connected to the ductwork), cassette (installed in rooms with a suspended ceiling), or convertible (a general-purpose unit for installing both on the floor and under the ceiling).

The operating principle of this type of air conditioner is based on the physical properties of the refrigerant, which – in the case of KAISAI air-conditioning systems – is the eco-friendly R32 refrigerant. This agent can condense or evaporate inside the indoor unit, depending on the air conditioner’s operating mode. In the cooling mode, the refrigerant evaporates inside the indoor unit and absorbs heat from the surroundings, which is then transferred to the outdoor unit and there extracted outside by condensation. When the unit is switched on in the cooling mode, pleasantly cool air is supplied from the indoor unit, and hot air is blown out from the outdoor unit, through the processes occurring inside the air conditioner. Additionally, any moisture contained in the air condenses on the cold heat exchanger, and it must be drained into the sewage system.

In the heating mode, both the indoor and outdoor units swap roles. This time, the air supplied from the indoor unit is warm, and can effectively heat up an office or an apartment, for example.

It should be remembered that the temperature of the outside air is the limiting parameter for the effective space heating. Since the performance of the unit usually drops significantly when below -15°C, it should not be used at such low temperatures.

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THE CORRECT INSTALLATION OF AN AIR-CONDITIONING SYSTEM

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THE CORRECT INSTALLATION OF AN AIR-CONDITIONING SYSTEM

Air-conditioning units must be installed by a qualified installation team. Contractors should have personal refrigeration certificates (F-Gas certificates) and electrical certificates. Portable air conditioners are the only type of equipment the user may install personally. However, the instructions provided in the accompanying instructions manual must be followed during installation.

The installation of other types of air conditioner requires the use of specialist tools, such as a vacuum pump, pressure gauges, refrigerant bottles, an electric meter, a flare tool, and also professional equipment for drilling holes. The cooling connections between the units are comprised of copper pipes, which are protected by thermal insulation with the correct thickness. It should be remembered that water condenses inside the indoor unit during cooling, and it must be drained into the sewage system, or directed outside the room. The best method of extraction is by gravitation, i.e. the pipes for draining condensate must be inclined. Sometimes, this is technically impossible, however, which necessitates using an additional condensate-extraction pump. The outdoor unit of an air conditioner is usually placed on the balcony or the façade, or on the roof of a building. During installation, be sure to provide service access and maintain the appropriate distances from the walls and barriers specified in the installation instructions. 

Remember to carry out periodic technical inspections of the installed air conditioners (preferably twice a year). Moreover, some units should be registered on a special database, i.e. the Central Register of Operators, in which mandatory inspections are also recorded, depending on the amount of refrigerant. Information on the equipment required for registering on this database should be provided by qualified technicians installing air-conditioning units.

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USING INVERTER CONDENSING UNITS

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USING INVERTER CONDENSING UNITS

Inverter condensing units are used as sources of cooling or heating for heat exchangers installed in air-handling units. The automation systems supplied with the units allow smooth control of the unit’s performance.

It is necessary to transmit a current signal in the range of 0-10V, which is usually related to the air temperature inside the air-handling unit for return or supply air, in order to ensure the adjustment of the cooling capacity. Unlike the older on-off technology, the inverter compressors applied in air-handling units maintain a stable supply-air temperature and ensure energy efficiency.

The condensing units from KAISAI are characterised by quiet and efficient operation in the cooling capacity’s range of 5-16KW.

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ENERGY LABELS – THE CLASSIFICATION OF ENERGY EFFICIENCY

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ENERGY LABELS – THE CLASSIFICATION OF ENERGY EFFICIENCY

Energy labels are affixed to every electrical appliance for domestic use sold within the territory of the European Union. This is regulated by a special EU directive. That directive also covers air conditioners below 12kW. Labels inform the user about the quality of the product, predominantly taking into account its energy efficiency. Thanks to the label, everyone can compare which device will have the lowest cost in use, before purchase. The assessment of energy efficiency, also referred to as the energy class, is indicated by letters. In the case of air conditioners, a scale from G (the lowest) to A +++ (the highest) is used.

When assessing savings in energy consumption for air conditioners, the following energy efficiency factors are also taken into account: SEER for cooling and SCOP for heating.

These factors determine the ratio between the cooling/heating capacity achieved by the air conditioner and the electrical power drawn by the unit from the mains, throughout the heating and cooling season, e,g. units with SEER=8, which corresponds to class A++, are capable of generating an average of 8kW of cooling energy from 1kW of electricity per season.

The inverter air conditioners from KAISAI feature the best energy class (A), while some of them even reach the maximum level A+++.

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AN AIR TO WATER HEAT PUMP VERSUS THE TRADITIONAL HEATING EQUIPMENT – WHICH SHOULD WE CHOOSE?

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AN AIR TO WATER HEAT PUMP VERSUS THE TRADITIONAL HEATING EQUIPMENT – WHICH SHOULD WE CHOOSE?

Regardless of whether our house is still under construction or we are already living in it, we would like a heat source that is supposed to provide us with the right room temperature to be safe, cheap to use, and requires as little attention as possible. Currently, there are many different types of heating equipment available on the market. Choosing the right one will ensure our comfort for many years to come.

Everyone, who has ever used the conventional solid fuel boiler, knows how much effort and time it takes to make sure that the boiler has been properly cleaned and the fuel tank filled. It is also important to remember to keep an adequate fuel reserve, which must be sufficient for the entire cold period. The use of fire presents an additional requirement for an efficient protection and warning system, both against fire and the emission of carbon monoxide. These disadvantages are compensated by the relatively low price of such solutions.

Heat pumps – Advantages

When compared to boilers, heat pumps seem to be the ideal solution for anyone who does not even think about operating a heating device, but at the same time wishes to have thermal comfort, both in the winter and summer. The cooling function is an interesting feature in their operation, as it is not available in the traditional heating systems. What’s more, if you still store fuel in the house, then using a heat pump will help you gain an additional room, which is an advantage of the heat pump that usually gets overlooked.

Another argument in favour of the modern solutions is the convenience of use, because automation helps save time. In this respect, we have already seen significant technological progress, and the times of “firing up the boiler for the winter” have come to an end. However, it has not been possible to eliminate this problem in all types of equipment, while the devices that successfully got rid of the problem generated more costs. The technological solutions used in heat pumps allow it to maximize comfort, while maintaining reasonable prices. In addition to the periodic inspection of the external unit’s level of soiling, it requires virtually no attention from the user.

Many people, who heat up their homes using the traditional boiler, fear investing in a modern heat source thinking that an air heat pump will not be capable of heating their home, which is completely unfounded. Whether your house has an area of 100 m2 or 250 m2, we can replace any boiler with a heat pump. Naturally, the primary task is to estimate the heat demand of a particular building, and then select the appropriate heating capacity of the device. A heat pump will provide us with thermal comfort, regardless of whether the house was heated with radiators or underfloor heating. In the case of radiators, check the highest required temperature of the heating system. It is often the case with buildings erected over a dozen or even several dozen years ago, that the temperature of 50˚C generated by the heating system, when it is – 20˚C outside, is enough to maintain a comfortable temperature inside the house. With older buildings, it is sometimes suggested to change radiators to bigger ones. This one-time expense will both improve the temperature comfort in the rooms and reduce the costs of the heating system, which will translate into savings.

Heat pump – Why is it worth a try?

The fact that we can practically eliminate the cost of operation, by using popular photovoltaic panels, is an additional advantage presented by the heat pumps. As the heat pump will only need electric energy and the thermal energy collected in the air to operate, it requires no additional fuel. Thus, it fits into the modern trend of “green energy” and allows you to significantly reduce expenses. Air heat pumps also do not require expensive drilling, while purchasing an air heat pump can often be up to 50% cheaper than a buying a ground-source pump.

If your house is only being built and you have reached the phase of selecting a heat source, please remember that a heat pump does not require erecting a smoke chimney, while the technical room should only accommodate a small indoor unit and a tank for hot tap water. The lack of additional infrastructure and small room dimensions make the air heat pump a much cheaper solution to purchase than other heat sources at the investment stage. The modern pleasing to the eye design of the heat pumps helps eliminate the need to hide them away and makes it possible to install them in other utility rooms, as well.

Modern heat pumps have more features than just the basic functions of heating, cooling, and producing hot tap water. The calendar function, which makes it possible to change the temperature in the building and in the hot tap water tank, the function of quick hot tap water heating, or the holiday function, thanks to which the device will lower the temperature in the house during the winter, in order to significantly reduce the heat demand of the building – all this affects the comfort and economy of use.

Summing up, modern heat pumps are a comfortable and economical solution, when compared to the traditional heating sources. Many of the functions and the applied technology make it possible for us to adapt their operation to our needs and save the floor space. If we additionally combine a heat pump with a photovoltaic system, the cost of heating a building will be practically zero, which is an important argument in its favour, if we consider obtaining government subsidies for the both solutions. We should also bear in mind that there is no combustion process occurring in the heat pump, so there is no emission of any toxic substances into the atmosphere, which has a significant positive effect on the environmental protection, on our health, and the fight against smog. They also do not require any additional sensors for gas or carbon monoxide leaks. We must also bear in mind that the heat pump is also the only heating device featuring a cooling function, making it the only device used for temperature control all year round.

Discover the KAISAI ECO HOME heat pumps – a green and reliable source of heat in your home.

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AIR TO WATER HEAT PUMP – AN INDEPENDENT SOURCE OF HEATING AND COOLING OR AS A HYBRID COMBINATION WITH AN EXISTING BOILER?

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AIR TO WATER HEAT PUMP – AN INDEPENDENT SOURCE OF HEATING AND COOLING OR AS A HYBRID COMBINATION WITH AN EXISTING BOILER?

Nowadays, we pay more and more attention to choosing the right and efficient source of heat in the house. The ever-increasing costs of buying traditional fuels and the ever growing pace of life make us look for devices, which will not only heat or cool the building for a cheap price, but also help reduce the time spent on their operation to a minimum. The obvious attribute of the new heat sources is also the price and the payback time of the investment, when compared to the cheap traditional solid fuel boilers.

We shall analyse different configurations of heat pump applications, depending on the phase an investment is at, when the decision is made: whether it is at the design or shell stage, or at the operation stage (when the building is already occupied), in order to offer a practical picture of the profitability of investing in new heat sources.

Design stage – air to water heat pumps

If the decision to choose a heating method is made, while the investment is still in the project phase, then the best solution seems to be using air to water heat pumps, taking into account the ever lower heat demand of modern buildings per 1 m2 and the increasingly attractive costs of investment. Unlike ground-source pumps, air to water pumps do not require any significant interference with the structure of a plot of land.

In the case of single-family houses with a floor area of less than 150 m2, occupied by a family of four, an 8 kW heat pump will be sufficient for the majority of applications. It will provide both thermal comfort and hot tap water for the household. It is worth noting that the investment cost regarding such a pump can be as much as half the cost of a ground-source pump! More than that, when it comes to operation, the costs of an air water pump can (but not necessarily) be only slightly higher.

If a building has a higher than average demand for heating power, for example resulting from its specific purpose, in order to provide more hot tap water, it is sufficient to use a 10 kW, 12 kW or 14 kW model, categorised under the same product class, which can easily meet the increased demand.

Practically every one of the offered heat pumps features modulated heating power and is equipped with an additional peak heat source, e.g. in the form of a 6 kW electric heater.

Remember that the use of a heat pump first and foremost provides the users with great comfort, because they do not need to worry about purchasing fuel, about the compulsory cleaning of the burner, or about storing extra fuel. Savings will materialise as early as at the stage of erecting the house. An air heat pump, combined with a domestic hot water tank, occupies less than 1 m2 of the building’s space, and it also more and more often features an aesthetic design, so there will be no need to build a large boiler room. The “saved” space can simply be used for residential purposes, or help reduce the cost of erecting the building, if we give up on the idea of having a boiler room and design a smaller house. 

If a building is equipped with a heat pump, there is also no need to have an expensive smoke chimney. This way, we will also avoid the expenses related to running a gas connection or erecting a container for gas, oil, or keeping a storage for solid fuel, in our house. Investing in an air heat pump will also help reduce the cost of maintaining thermal comfort when using an underfloor heating system.

An existing building – hybrid boiler plants

The example described above pertains to a model application of a heat pump in a modern, newly erected building. However, what would we do, if we wanted to improve the comfort of living and reduce heating bills in an already existing house, in which nobody had thought about a heat pump at the design stage?

The basic question is: what is the real demand for heating power in the particular building and can we reduce it? In some cases, before we start replacing a central heating system, it will be necessary to carry out thermal modernisation of the building (changing window frames, insulating walls, ceilings, etc.). Such actions will not only reduce the building’s heat demand, but they will directly translate into reduced heating bills and also allow for a real adjustment of the required power for the heating equipment. When modernising a heating system, we can, for example, buy a heat pump with less power demand than the furnace we have used so far. This will translate, firstly, into lower investment costs, and secondly, into lower operating costs.

However, there are investments, where a complete change of an entire heating source to a heat pump is not cost-effective, because of high investment costs resulting, for example, from difficulties in adapting the building. If that is the case, we can consider a hybrid boiler house, i.e. installing an air to water heat pump, in combination with the existing heat source. Such a solution will reduce the operating costs and offer environmental advantages.

In this variant, our analysis concerns a house built 30 years ago, with a total area of 300 m2, equipped with an oil boiler, which can often have a heating power demand exceeding 20 kW, at a design temperature of -20°C. During the colder winter season, oil consumption can be as high as 4500 l/year. A 14 kW heat pump should meet 100% of the building’s energy demand, with the outside temperature falling down to about 0°C. When using a hybrid boiler house below this temperature threshold, an oil boiler can be activated as an auxiliary source of heat, for example.

However, we should bear in mind that the latest temperature measurements in the climatic zone III indicate that the outdoor temperature falls below 0°C for only about 1,500 hours a year, which amounts to 17%. For the overwhelming majority of the year, the only source of heating for both the building and hot tap water will therefore be a heat pump, which is much cheaper to operate and eco-friendly.

Combining an oil, gas, or eco-pea coal boiler with a heat pump can significantly reduce your annual heating bills and simply increase your comfort, if solid fuel boilers are used.

Let us remember that there are a number of factors influencing a particular investment and the operating costs generated by heat pumps. We must take into account not only the demand for heating power, but also the delivery temperature of a heating system. The lower it is, the cheaper it is to operate a heat pump. The actual amount of hot tap water consumed and, for example, connecting the entire system to an existing fireplace with a water jacket, or to solar collectors, can also have an additional impact on the profitability of the investment. The correct connection of such a system and potential modernisation of the building’s heating system is crucial for the whole system to operate efficiently and cheaply.

Summary

The use of an air to water heat pump for heating up buildings and hot water is a good solution, both when the investment has only reached the design phase and when the buildings already exist. In both cases, this will significantly reduce the operating costs and can prove profitable for new projects, from the investment perspective. Hybrid systems can be offered as an advantageous solution for modernising the heating system, in terms of economy, ecology, and comfort for the user.

Discover the KAISAI ECO HOME heat pumps – a green heat source for both single-family, multi-family, and commercial buildings.

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AIR-TO-WATER HEAT PUMP FOR CENTRAL HEATING AND USABLE WARM WATER

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AIR-TO-WATER HEAT PUMP FOR CENTRAL HEATING AND USABLE WARM WATER

An air-heat pump operates according to the similar principle as air-conditioning systems or refrigerators. Each of these devices features three circuits. 1) A lower source – i.e. from where the pump absorbs heat, 2) A cooling circuit – i.e. a set of elements and devices, thanks to which heat is transferred from the lower source to the upper source,  and 3) An upper source – a heating system, e.g. radiators, underfloor heating, usable warm water.

The air-to-water heat pump’s principle of operation is very simple, and is based on 3 physical phenomena commonly occurring in everyday life: evaporation, compression, and condensation. During the process of evaporation (the evaporator), the refrigerant draws heat from the surroundings – in this case, the outside air. Please note that refrigerants are capable of evaporating at very-low temperatures (even at -20°C). After evaporation, the refrigerant has accumulated energy,
but the temperature of gas is too low to transfer this energy directly to the heating system.

The temperature of the gas in the cooling system must be raised in order to heat the building efficiently. The heat pump’s compressor is used for this purpose. During compression, the pressure and temperature of the gas increase.

Under high pressure and at high temperatures, the gas travels to a condenser (condensation), where heat is transferred to the heating system. Then, an expansion valve reduces the pressure of the condensed refrigerant, while the appropriate amount of refrigerant is supplied to the evaporator, and then the whole process is repeated.

 

The process behind the operation of air-to-water heat pumps means that up to 75-80% of the heat entering the heating system is free of charge, as it is obtained from the outside air. The remaining 20-25% is the electricity needed mainly for the compressor and the circulation pumps of the heating system.

How much current does an air-to-water heat pump draw / consume?

The energy consumption of a heat pump depends on many factors, the most important of which include the real heat demand of the building, the temperature of the heating system, the amount of usable warm water used, the outside temperature, and the correct installation of the entire heating system.

Let’s make the following assumptions:

  • the usable area of the house is about 150m2,
  • the temperature in the building is 21°C,
  • the house is inhabited by 4 people,
  • underfloor heating is installed,
  • and the building is constructed using modern heating technology (50W/m2).

Depending on the climatic zone, the heat pump, together with the peak heat source, should draw about 5000÷5500kWh from the mains. If the price of 1kWh of electricity is 0.56 PLN, then the annual cost of heating of both your house and the usable warm water should not exceed about 3,000 PLN. It should be remembered that this amount can be significantly reduced by improving the thermal insulation of a building, using a cheaper energy tariff, or by installing a photovoltaic system.

Selecting an air-to-water heat pump

It is essential that the heat pump is correctly matched to the specific system and user preferences. The basis for selecting the model (power) of a pump is to know the building’s demand for the effective energy or power at the design temperature (e.g. -20°C), and the amount of usable warm water. However, that is not all you need to ensure you select the correct pump.

The following parameters should be taken into account:

  • the temperature of the heating system,
  • the temperature you wish to have in your home,
  • having zone control in the rooms,
  • the size of the sable warm-water consumers, e.g. a large shower head,
  • and the needs regarding heating, and, possibly, cooling, in a building.

It is very important to specify the aforementioned details in order to select the correct heat pump and enjoy the comfort of a home-heating system, and low heating bills.

Become familiar with the KAISAI ECO HOME heat pumps, which can both heat or cool your home and provide usable warm water.