What a heat pump is: operating principle, advantages and disadvantages

Post author
04 Jul 2022
17 мин чтения
3 comments
1452
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Content
  1. What a heat pump is and the principle of its work
  2. Classic heat pump design
  3. Types of heat pumps
    1. Air-to-air heat pump
    2. Air-to-water heat pump
    3. Ground-to-water heat pump (geothermal)
    4. What a water-water heat pump is
    5. Spiral collector
  4. Requirements for energy sources
  5. Heat pump air conditioning
    1. What a heat pump with active cooling is
    2. Passive cooling
  6. How the efficiency of a heat pump for heating is calculated
  7. Pluses and minuses of heat pumps
  8. When to use a heat pump in ukraine
  9. FAQ
    1. Why do we use a heat pump?
    2. How does a heat pump work for heating?
    3. How much does a heat pump cost on average?
    4. What is the efficiency of heat pumps?

What a heat pump is and the principle of its work

What is a heat pump? This is equipment that allows you to efficiently convert electrical energy into heat or cooling. The main feature of a heat pump is that it is able to generate high potential energy in exchange for minimally expended resources.

In doing so, it can perform three functions:

  1. room heating,
  2. room cooling,
  3. hot water heating.

Read below about existing types of heat pumps and how they work.

Classic heat pump design

The design of the heat pump consists of two blocks - outdoor and indoor. In a geothermal heat pump or a water-to-water pump, the function of the outdoor unit is performed by soil and water, respectively.    

Heat pumps operate according to the Carnot cycle: 

  1. Outdoor unit → compressor
    Heat pumps use energy from an external source. In geothermal heat pumps, this is the energy of the earth, which comes from vertical or horizontal wells, in water-to-water heat pumps, the energy of water is used, and for air source heat pumps, it is external street air. The compressor compresses the heat carrier (Freon), generating heat and transferring it to the condenser. 
  2. Compressor → condenser
    Through the condenser heat exchanger, the generated heat enters the heating circuit.
  3. Condenser → indoor unit
    After the transfer of heat, Freon returns to the heat exchanger of the external air unit or to the ground in a geothermal pump or to the water of a water-to-water heat pump. Then the cycle repeats. 

Thanks to this principle of heat transfer, the energy conversion efficiency is much higher than the energy spent. At the same time, the savings are obvious – the average energy conversion efficiency for air thermal is 3.5, and for geothermal – 5.

Types of heat pumps

We discussed what a heat pump is. Let’s look at their types, which differ in the source of energy. 

Air-to-air heat pump

Any air conditioner, in fact, is an air-to-air heat pump. What is the difference? On the other hand, the air-to-air heat pump operates at low temperatures, down to -25 °C.

In these heat pumps, you need to consider:

  1. Noise characteristics
    Unlike radiators, where natural convection occurs, an engine works here, which mechanically passes air. Therefore, the noise will be noticeable.
  2. Zero inertia of heat preservation
    There are no auxiliary elements that retain heat. If the system stops, the room is instantly cooled.
  3. Cold building structures
    The window area is considered the coldest. If there is no additional blown element along the double-glazed window, the temperature here will always be lower.
  4. Climate of the region
    In Ukraine, this type of heat pump is not popular, in comparison with the warmer countries of Europe - Spain, Italy, Portugal. There are no frosts, so such a system is used as a convenient and quick solution.
Pump tipeAdvantagesDisadvantages
Air-to-air heat pump✓  works at a temperature of -25°C,
✓ нdoes not require the design of a heating system,
✓ easy installation,
✓ low cost.
✓ does not provide DHW (hot water supply), only air heating and cooling,
✓ noise from the engine is heard,
✓ does not accumulate warm air.
Pump tipe
  • Air-to-air heat pump
    Air-to-air heat pump
Advantages
  • Air-to-air heat pump
    ✓  works at a temperature of -25°C,
    ✓ нdoes not require the design of a heating system,
    ✓ easy installation,
    ✓ low cost.
Disadvantages
  • Air-to-air heat pump
    ✓ does not provide DHW (hot water supply), only air heating and cooling,
    ✓ noise from the engine is heard,
    ✓ does not accumulate warm air.
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Air-to-water heat pump

External air-water heat pump unit in section

It is common in Europe, where compact and high-tech houses are built. Such a heat pump uses the heat of external air, heats it by compressing Freon in the compressor and transfers it to water through the condenser. It can cool and heat air, as well as heat water.

When installing an air-to-water heat pump, it is necessary to provide a low-temperature heating system, which implies the maximum coverage area with a water-heated floor and the presence of auxiliary elements - floor convectors, fan coil units and radiators.

For the high efficiency of such a system, it is important to take into account the following factors:

  1. High-quality building construction
    Efficiency depends on how energy efficient the house itself is. Insulated walls, roofing, foundation, energy-saving double-glazed windows – all this ensures minimal heat loss.
  2. Ventilation system
    Both in an apartment and in a house, a ventilation system with heat recovery must be installed.
  3. Low-temperature mode
    The heat pump operates at lower temperatures than, for example, a gas boiler.
  4. Using fan coils for cooling mode
    In winter, fan coil units are used as auxiliary elements, in summer - as the main solution for cooling mode
Pump typeAdvantagesDisadvantages
Air-to-water heat pump✓ provides air cooling and heating, as well as water heating,
✓ energy efficiency - energy conversion efficiency is 3.5,
✓ affordable price.
✓ must be used with a backup heat source if the area of the room is more than 190 m2


Pump type
  • Air-to-water heat pump
    Air-to-water heat pump
Advantages
  • Air-to-water heat pump
    ✓ provides air cooling and heating, as well as water heating,
    ✓ energy efficiency - energy conversion efficiency is 3.5,
    ✓ affordable price.
Disadvantages
  • Air-to-water heat pump
    ✓ must be used with a backup heat source if the area of the room is more than 190 m2


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Ground-to-water heat pump (geothermal)

The source of energy for a geothermal heat pump is the heat of the earth. The temperature of the soil, regardless of the season, is +14-15 °C at a depth of 70 m; therefore the energy conversion efficiency here is 5 (energy conversion efficiency of the air pump is 3.5). This self-sufficient and highly efficient equipment contributes to a stable and constant heat exchange. In winter, the house is heated by taking cold into the ground, and in summer, the accumulated cold is used for cooling.

  • When installing the heat pump horizontally, the collector is placed along the surface of the earth, at a depth of about 2 m, where the soil does not freeze through. The larger the coverage area, the greater the pump power.
  • When installed vertically, the collector is placed in wells 70-80 m deep. Here the power increases due to the number of heat exchange probes.
Pump typeAdvantagesDisadvantages
Ground-to-water✓ provides air cooling and heating, as well as water heating,
✓ high and stable energy conversion efficiency
✓ high cost
✓ large area required.
Pump type
  • Ground-to-water
    Ground-to-water
Advantages
  • Ground-to-water
    ✓ provides air cooling and heating, as well as water heating,
    ✓ high and stable energy conversion efficiency
Disadvantages
  • Ground-to-water
    ✓ high cost
    ✓ large area required.

In household use, the difference between an air-to-water pump and a geothermal one is in two factors: the energy conversion efficiency and the area of ​​​​application, since an air pump is used up to 250 m2, and a geothermal pump is 250 m2 and above. However, in any type of pump, the weather dependence factor is always taken into account when the heat pump is optimized for certain climatic conditions in a particular area.

What a water-water heat pump is

It is used in the industrial sector, as access to large bodies of water is needed. These heat pumps convert energy by pumping water (rivers, lakes), where the temperature at the bottom of the reservoir is stable all year round. The heat pump device is laid on the bottom of the reservoir and the longer its length, the more powerful the pump. As an example, such a pump can operate in a system with hydroelectric power plants. When the hydroelectric power plant dumps the generated heat into the water, it can be used by distributing it to nearby cities.

Pump typeAdvantagesDisadvantages
Water-to-water✓ provides air cooling and heating, as well as water heating,
✓ high energy conversion efficiency all year round.
✓ costly installation,,
✓ difficult to maintain.
Pump type
  • Water-to-water
    Water-to-water
Advantages
  • Water-to-water
    ✓ provides air cooling and heating, as well as water heating,
    ✓ high energy conversion efficiency all year round.
Disadvantages
  • Water-to-water
    ✓ costly installation,,
    ✓ difficult to maintain.

Spiral collector

Also receives energy from water, suitable for those who have their own reservoir. The heat exchanger is immersed in water and held on special floats. It is important that the collector do not silt up, and the area of the reservoir is sufficient so that it does not freeze in winter.

Pump typeAdvantages Disadvantages
Spiral collector✓ provides air heating and cooling, as well as water heating
✓ high-energy conversion efficiency.
✓ complexity of installation and maintenance.
Pump type
  • Spiral collector
    Spiral collector
Advantages 
  • Spiral collector
    ✓ provides air heating and cooling, as well as water heating
    ✓ high-energy conversion efficiency.
Disadvantages
  • Spiral collector
    ✓ complexity of installation and maintenance.

Requirements for energy sources

Each alternative energy source has its own characteristics. 

  • Air. The climate of the region is considered, since the energy of the air is vulnerable to temperature changes. The air pump operates at -20-25 °C, but there is a need for backup heat sources.
  • Ground. With a vertical installation, wells are drilled in the ground for laying pipes, and with a horizontal installation, they are laid along the surface of the earth. Special soil preparation is not needed.
  • Water. The private sector requires access to the reservoir through a pipeline, while the industrial sector needs access to large volumes of water and plenty of resources to service it.

Heat pump air conditioning

Air source heat pumps always operate in active mode, while ground source heat pumps can cool the air in passive mode.

What a heat pump with active cooling is

Active cooling of any heat pump means its actual operation – when the compressor starts and consumes electricity to cool the liquid inside the system to a temperature of + 7 °C. Then, depending on the type of pump, the cooled heat carrier is supplied to the premises through fan coil units or floors and walls. 

Passive cooling

Passive cooling can be implemented with the help of a geothermal heat pump. This is due to the cold that enters the ground under the house in winter. In spring, cold water rises and cools the rooms directly through the fan coils. When the ground temperature begins to rise and reaches above +10°C, then active cooling will begin thanks to a compressor.

How the efficiency of a heat pump for heating is calculated

When calculating efficiency, several factors must be taken into account.

  1. Heat pump power
    The power of the air and geothermal pump is selected according to the thermotechnical calculation of the building for the winter period and the refrigeration calculation for the summer. It is important that there is enough power to generate energy and make up for possible heat losses.
  2. Local climate
    The efficiency of an air source heat pump is directly affected by the ambient temperature. The choice of temperature indicators at which the heat pump switches to a backup energy source depends on this. The operation of a geothermal heat pump is not affected by the temperature, since the earth has a stable temperature and always produces the right amount of energy.
  3. Room space
    An air source heat pump can effectively operate in a room up to 190 m2 as long as a building has a high-quality structure, that is, minimal heat loss. However, if the area is larger, auxiliary elements are needed. A geothermal heat pump will work flawlessly both for cooling and heating air, and for hot water supply for large areas – from 190 m2.

Two main coefficients are also calculated:

  • Thermal resistance coefficient of all structures (R) in winter,
  • G-factor in the summer, when the transmission capacity of the double-glazed unit is taken into account.

According to the Construction Norms & Regulations, in Kyiv and the Kyiv region, heating should be calculated for temperatures up to -22 °C. An air source heat pump can operate independently at temperatures down to -7-10 °C, but it is important to consider the square area and the quality of the building insulation. If the temperature is lower, auxiliary devices are used. Geothermal heat pumps can operate independently at a given temperature and do not require additional energy sources.

ORDER THE SELECTION OF THE HEAT PUMP

Pluses and minuses of heat pumps

Heat pumps do not have significant disadvantages. The efficiency of their use depends on the type of pump that is selected for a particular room. 

The main advantages of heat pumps:

  1. Efficiency
    The energy conversion efficiency of a heat pump can be as high as 1:6
  2. Practicality
    The heat pump can operate throughout the year for heating, cooling and DHW.
  3. Eco-friendliness and durability
    The heat pump does not harm the atmosphere with waste emissions and does not require repair for many years.
  4. Safety
    Warm pumps work without open fire, and in the event of a breakdown or its stop, protective automation is activated.
  5. Ergonomics
    The indoor units are compact, and the largest part of it, the outdoor unit, remains outdoors.

Features of operation of air-to-air and air-to-water heat pumps:

  • Low-temperature mode
    The heating mode will work down to -25 °C, but requires auxiliary equipment. Independent work is possible at temperatures up to -7 °C and room area up to 190 m2.
  • Basic functions – heating and cooling air
    DHW is possible when installing an air-to-water heat pump; an air-to-air heat pump does not provide this function.
  • Inconstant energy conversion efficiency
    The efficiency of air heat exchange depends on the external air temperature. The energy conversion efficiency decreases at low temperatures.

Features of operation of ground-to-water heat pumps:

  • Independent equipment
    The geothermal pump works at low temperatures and does not require auxiliary elements for heating, cooling and DHW.
  • For large rooms
    Suitable for rooms with an area of ​​190-250 m2
  • Complicated installation
    Installing a geothermal pump is expensive and complicated, but its efficiency is high and stable.

Features of operation of water-to-water heat pumps:

  • Industrial sector
    Suitable for the industrial sector as it requires large volumes of water for power generation and many resources for maintenance.

When to use a heat pump in ukraine

For the last two years, Ukraine has been catching up with Europe in terms of technology. Europeans have been working for decades to abandon expensive gas and switch to new highly efficient equipment. In addition, Europeans receive a 40% subsidy when they switch from a convection boiler to a heat pump. 

Ukrainians have long used cheap gas from Russia as their main source of heat. At the moment, there is no subsidy system, although until 2020, 3000 kilowatt-hours were allocated to the house with a 50% discount and another 50% discount for the night tariff. Perhaps such a system will appear again in the future.

Therefore, heat pumps are important and should always be used in Ukraine. In 2014, there was a push to promote the transition to alternative energy sources. In terms of energy resources, Ukraine is a self-sufficient country, which is now in the phase of abandoning dependence on natural resources and switching to more efficient ways of generating energy - electric boilers or heat pumps..

FAQ

Why do we use a heat pump?

What is a heat pump? It is a state-of-the-art energy conversion solution that covers basic consumption needs - cooling, heating and DHW.

Thanks to this heat exchange, a minimum amount of energy is consumed, and the efficiency is multiplied several times. This guarantees significant cost-effectiveness, and also provides several additional benefits: comfort in everyday life, safety and environmental friendliness of use, versatility for any type of building, climate and specific energy tasks.

How does a heat pump work for heating?

In the article we talked about what it is. A heat pump is a device that converts electricity into heat energy. Heat pumps differ in energy sources. The general principle of their work is the same, but each has its own functional features.

  • For example, an air source heat pump uses the energy of the air and exchanges heat between outdoor air and indoor air, but requires auxiliary energy sources at low temperatures. An air-to-water heat pump can also provide domestic hot water.
  • If the ground-to-water heat pump system design, the heat source is the ground, which has a stable temperature throughout the year. This is independent equipment, the operation of which does not depend on external temperatures. It generates heat and provides hot water without additional equipment for large rooms.
  • The water-to-water heat pump uses large volumes of water to generate energy and is used in the industrial sector.

How much does a heat pump cost on average?

The average price of an air and geothermal heat pumps is from 6,000 to 10,000 € for houses up to 300 m2. However, for a geothermal pump, you need to calculate additional costs – earthworks, probes, fan coil units. Alter Air engineers provide such a calculation individually.

What is the efficiency of heat pumps?

Efficiency is determined by the amount of thermal energy that is generated from electrical energy. The energy conversion efficiency depends on the temperature difference between the external environment and the internal one. Depending on the type of heat pump, it can be from 1 to 6, which significantly reduces costs and increases comfort levels.

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Testimonials and questions
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  • 5 / 5

    Михаил Петрович

    Спасибо за информацию. Долго сомневались, но вы нас "добили", особенно понравился видео - обзор. Все четко и по существу. Ничего лишнего, все по теме.

  • 5 / 5

    Ольга

    Статья соответствует названию - все описано четко и доступным языком. Понятно будет даже для новичков в этой области.

  • 5 / 5

    Серега

    Недавно я приобрел тепловой насос в компании Alterair, и должен сказать, что весь процесс прошел гладко и без проблем. Сотрудники компании смогли ответить на все мои вопросы и проблемы, учитывая это подобрали тепловой насос воздух-вода Sherpa S2 E 10, Италия. С установкой проблем не возникло, мастера прибыли вовремя и работали профессионально, по ходу они рассказали, как работает нанос и какие его меры предосторожности. Но как я понял, у меня все просто, потому что везде теплый пол и низкотемпературная система. Как только тепловой насос был установлен, я сразу же заметил разницу насколько быстро и эффективно, он справляется со своей задачей. Само оборудование легкое в использовании и имеет простое управление, по крайней мере у меня с этим сложностей не возникло.

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