Partner login


AIR-COND Klimaanlagen-Handelsgesellschaft m.b.H.

Haushamer Straße 2
8054 Graz-Seiersberg, AUSTRIA

+43 316 80 89

+43 316 82 63 71

How a heat pump works


All ESTIA heat pumps operate on the same principle. Energy is generated from the surrounding air and used to heat water. With air-to-water heat pumps, also known as split systems, the system comprises air source heat pumps, which serve as the outdoor unit and generate and convert energy, and an indoor unit, which forwards the generated heat to the heating circuit. Both are linked by means of a closed circuit. The refrigerant circulating in this circuit has a boiling point way below –20°C and, unlike water, cannot therefore freeze.

Heat exchange using ESTIA

  1. The fan in the outdoor unit draws in the outdoor air, which is fed to the heat exchanger.
  2. Given its low boiling point (R32 =
    – 51.7 °C, R410A = – 48.5 °C), the refrigerant, which until that point was liquid, changes its stage in the heat exchanger and evaporates.
  3. The compressor draws in the gas in the indoor unit and compresses it. The refrigerant temperature rises as the pressure levels increase.
  4. The hot refrigerant now reaches the heat exchanger in the indoor unit (Hydrobox | All in One) and emits its thermal energy to the hot water heating circuit.
  5. The refrigerant cools as a result, becomes liquid again and the process is repeated.



Both in terms of acquisition costs and operations, a heat pump is a cheap form of heating as it uses so little electricity.


p>Thanks to the smart grid, a photovoltaic system can be easily incorporated, allowing you to produce the electricity you need yourself.

Funding available

You can get a grant for a heat pump heating system, such as the Austrian government's “Raus aus dem Öl” funding scheme for heating.


Air source heat pumps work with radiators just as well as underfloor heating systems and can be used for both heating and cooling.


The intelligent compressor technology makes heating operation possible at temperatures down to –25°C and cooling at temperatures up to +43°C.

Environmentally-friendly and conserves natural resources

Air-based heating is CO2-neutral. There is an infinite supply of air and it doesn't have to be stored.

"Since we started using ESTIA, our heating costs have fallen and we are finally not dependent on the price of fuel."

Nora and Markus FRIEDRICH, homebuyers 2014


A heating, air conditioning and ventilation expert planner will plan your heating system for you. This expert planner will determine the heating capacity of the building on the basis of your energy performance certificate. If you don't have a certificate, a heat load calculation can be produced instead. These values serve as the basis for designing the heating system. All our TOSHIBA partners would be happy to undertake this work for you.


Even though it is not prescribed by law, here at TOSHIBA we would recommend having your air source heat pump maintained annually by an expert. Detecting faults early on means that they can be quickly remedied and helps you to avoid costly and more serious repairs. All heat pump components in the indoor and outdoor unit are checked during maintenance.


How does a heat pump work?

The heat pump uses refrigerant to extract energy from the outdoor air and transfer it to a higher temperature that can be used for your heating.

Why is an air-to-water heat pump the ideal investment for the future?

An air-to-water heat pump combines the advantage of low acquisition costs with extremely low operating costs and therefore makes efficient use of renewable energies.

What can you use an air-to-water heat pump for?

A heat pump can be used to heat as well as cool in many different ways, for example to prepare hot water in new builds or refurbishments with radiators, underfloor heating, panel heating as well as to help heat swimming pools.

Is a TOSHIBA heat pump eligible for funding?

TOSHIBA heat pumps have all the necessary certificates and requirements to make them eligible for funding. However, grants depend on the country, city, and on the local electricity supplier. You will find a list of potential funding opportunities in Austria at

What does it cost to run a heat pump?

This depends on various factors, such as local circumstances, the insulation in the building, and personal thermal requirements. However, generally speaking the heating costs of new buildings fitted with air-to-water heat pumps are way below €50 a month.

How noisy can a heat pump be?

To maintain good relations with neighbors and the rest of the local community, you should keep noise levels to 30 db(A) at the boundary to your property. This means that your TOSHIBA heat pump can be installed 6 meters away from your neighbor's property.

What does SPF stand for?

Seasonal Performance Factor is a measure of the efficiency of heating systems operated with heat pumps. It represents the ratio between the energy supplied (electricity) and the heat actually generated over the duration of one year and serves as a benchmark for cost-effectiveness calculations.

What is the life expectancy of a heat pump?

An air-to-water heat pump has the same service life as other conventional heating systems, which is ensured by regular maintenance and guaranteed 15-year spare parts availability.

How much space do you need for a heat pump?

The transfer station takes up 93x53x36 cm (HxWxD) of space, so the heat pump can be used even in small rooms.

Why is an electric backup heater required?

The certified heat pump partner will design the TOSHIBA heat pump in line with your building's requirements, so that the electric backup heater is only required for backup heating at the lowest outdoor temperatures.

Is the combination of heat pump/solar system or photovoltaics possible?

You can integrate solar energy into your heat pump setup and this may help improve efficiency levels.

Can I use a heat pump for cooling?

In winter you can generate heat using your panel heating system and in summer you can use this to temper your room. Active cooling is possible via fancoils.

Does the heat pump work even at sub-zero temperatures?

Although the efficiency of the system decreases at a very low outdoor temperature, heat pumps are able to generate heat even from an outdoor temperature of -25°C.

How efficient is the heat pump in summer when I only need hot water?

As heat pumps work even more efficiently at higher outdoor temperatures, you can produce hot water temperatures of up to 55°C flawlessly and cost-effectively at outdoor temperatures of up to 35°C.

Up to what supply water temperature is it practical to operate a heat pump?

The lower the supply water temperature, the more energy-efficient the heat pump is. Supply water temperatures of max. 60°C are possible, but for radiators, 50°C is usually sufficient if they are in continuous operation.

How do you determine the correct power capacity of a heat pump?

The correct design determines the efficiency of the heat pump. For our systems, this is carried out using the performance table in order to ensure the required heating capacity of your building up to the standard outdoor temperature, without the use of the backup heater.

What can I control using the heat pump?

The heat pump has an intelligent control logic that independently regulates the heating temperature of the radiators, the underfloor heating, and the hot water depending on the outdoor temperature.

How easy is commissioning?

Due to ready-made installation diagrams and associated commissioning parameters, commissioning is a stress-free and quick task for the specialist. Using the step-by-step guide in the APPENDIX/manual or APP, each parameter can be adjusted to suit individual requirements.

What do I need to connect the heat pump to a building control system?

External control or integration into a building control system via KNX or MODBus is possible with additional PCBs.

Who do I contact if I have any questions?

Should a malfunction or problem occur in your system, the certified heat pump installer will be on hand to provide you with advice and assistance.

What does nominal capacity mean?

Nominal capacity is the unit capacity at a specified operating point.

What does heating limit temperature mean?

Daily mean temperature from which a building must be heated. Days on which the daily mean temperature is below the heating limit temperature are classed as heating days.

What does standard outdoor temperature mean?

The average lowest expected outdoor temperature for which your heating system is designed.

What is COP?

COP stands for Coefficient Of Performance and specifies the ratio of electrical energy used to thermal energy received at a given operating point.

Do you still have questions about our air-to-water heat pumps? Don't worry, you're not the only one. You may well find the answers in our FAQ. You can of course contact us in person or leave your contact details, including

your zip code, and one of our reliable and local sales partners will get back to you as soon as possible.

+43 316 80 89

Copyright 2024 AIR-COND International GmbH  All rights reserved.