How does exhaust air heating work?

Are you wondering how this technology works, maybe even if it works? In this short guide we explain how our systems function and why our air heating pumps are good for both the environment and the wallet.

Exhaus Air Heating
Exhaus Air Heating Kondensor

In this article we describe an exhaust air heat pump, however, the general principle is the same regardless of the type of heat pump.

Hot indoor air is brought to the pump from the kitchen and bathrooms of a house. Fresh air comes in through ordinary window valves or wall valves. Inside the pump, the warm indoor air passes through the evaporator in which a cooled refrigerant flow. The air cools while the refrigerant absorbs its heat energy and evaporates to gas. The cooled indoor air exits through the house wall as a residual product.

The gasified refrigerant goes to a compressor which compresses the air. As the pressure rises the temperature of the gas also rises, from about 10 degrees Celsius (50 °F) to about 80 degrees (176 °F).

In this high pressure range, cold water introduced into the condenser. This cold water is heated by the compressed hot gas which then condenses in back to its liquid state. The heated water is then distributed into the house as heating and hot water.

When the refrigerant has given off its heat to the water, it passes a valve where pressure and temperature drop sharply. The cold and mainly liquid refrigerant then returns to the evaporator.

Under which conditions is it possible to install an air exchange heat pump?

  • The house must have ventilation ducts from sanitary rooms and kitchens
  • The house must be equipped with windows or wall valves suited for fresh air intake. Alternatively, you can take in air through an air duct system
  • The house should have a hot water heating system, e.g. radiators or floor heating.
  • Kitchen fan air in a separate duct

One advantage of an exhaust air heat pump is that it uses the indoor air as an energy source. The energy content in it is considerably higher than cold outdoor air. Another advantage is that the system supplies the house's ventilation, resulting in clean and comfortable indoor air with no need for separate active ventilation.

Exhaust air heating in a detached house

Normal passive vents let in fresh outdoor air into the house. The air circulates through the rooms of the house by exhaust air diffusers. Spent air ventilates out in the duct system (and the kitchen fan has its own exhaust air duct). This warm air fed to the heat pump which in turn supplies the house with both heating and hot water. The air which has passed the heat pump is subsequently vented out of the house. At this point the heat pump has taken advantage of all the energy of the spent indoor air and recycled it into heating.

Exhaust air heating Comfortzone detached house

Cooling in comfort

ComfortZone is the first manufacturer of exhaust air heat pumps to have developed a new type of heat pump that also provides the house with cooling when needed.

The heat pump RX-C provides heating to the house during normal operation, but in addition has a cooling mode where the coolth the unit generates is used to provide what we call “Comfort cooling”. In order to realize the cooling potential of the unit an air handling unit, T15, must be connected to the heat pump.

With Comfort cooling, the inbound air temperature can be adjusted to the desired level. It may also circulate cool water in the house's underfloor heating pipes, all the while the heat pump continues to produce hot water for the shower and tap water. It is simply a two-in-one solution – cooling and heating in one and the same heat pump.

ComfortZone Cooling is available in versions RX-C35 and RX-C50 and is ordered via our dealers.

Cooling in comfort Comfortzone
Why Comfortzone?

An efficient solution with exhaust air as the only heat source

ComfortZone is developing innovative solutions with high requirements on longevity and reliable operation. Our units achieve effects of 3.5 kW, 5 kW or 6.5 kW by using only exhaust air as a heat source.

Exhaust air heating Comfortzone
01. Engineered with passion

Our pumps are known for high efficiency, quiet running, stylish design and low heating costs.

02. Modern all the way through

Our heat pumps are design award-winning and built with the most modern components. ComfortZone innovates – we were the first manufacturer to add an electronic expansion valve to increase performance. Through our updated user interface and remote control app we supply the user-friendliness the market is looking for.

03. Designed for efficiency

The air flow analyzed with respect to turbulence provides optimal energy extraction. Our new tank layout has increased the water holding capacity. We have also opted to use the latest and greatest compressor technology which ensures high energy savings.

04. Designed for quiet

The highly efficient sound proofing also provides effective vibration damping. Additionally, it is easy to configure away any unwanted sound effects (such as beeps) in the display user interface.

05. Designed for simplicity

It is easy to connect pipes to our pumps. Furthermore, we designed them to be easily serviceable; the internals of the unit is roomy and the components are accessible and service-friendly.

06. Based on experience

ComfortZone has been around since 2003, and created the first exhaust air heat pump of the so-called condensing type which cools the exhaust air to -15 degrees Celsius. Our collective experience and do-better attitude has been condensed into this new product line. We are building machines with the goal of meeting tomorrow’s energy saving requirements, today.

07. Built for the whole world

The units are compatible with three-phase and single-phase as well as different mains voltages. Built-in program for heating floor tiles according to government regulations in a number of countries. Power efficient fan that meets the requirements in a number of countries. Meets Swedish requirements for energy efficiency without equal.

08. A safe purchase

All models are extremely robust and reliable due by design and construction. Manufacturers guarantee for six years is included in the price and can be extended (applies to Sweden).

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