Technical glossary
AirX, AirModule E 9/15, Airbox E/S – 6 720 810 266 (2014/10)
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Technical glossary
Heat pump
The central heat source. Placed outdoors, also referred to as an outside 
unit. Contains the cooling circuit. Waterborne heating or cooling is 
transferred from the heat pump to the heat pump module.
Heat pump module
Placed indoors and distributes the heat from the heat pump to the 
heating system or the water heater. Contains the user interface and the 
circulation pump for the water to the heat pump.
Heating installation
Includes the entire installation, with heat pump, heat pump module, 
water heater, heating system and accessories.
Heating system
Comprises the heat source, cylinders, radiators, underfloor heating 
system or fan convector or a combination of these if the heating system 
has several heating circuits. 
Heating circuit
The part of the heating system that distributes heat to different rooms. 
Consists of pipework, circulation pump and either radiators, underfloor 
heating system loops or fan convectors. Only one of these alternatives is 
possible in one circuit, but if there are e.g. two circuits in the heating 
system, then one may comprise radiators and the other underfloor 
heating system loops. A heating circuit can be installed with or without a 
mixing valve.
Heating circuit without mixing valve
A heating circuit without mixing valve does not contain a mixer; the 
temperature on the circuit is maintained completely b y th e he at f rom th e 
heat source.
Heating circuit with mixing valve
A heating circuit with mixing valve contains a mixer, which mixes in the 
closed circuit water with the water from the heat pump. This means that 
the heating circuit with mixing valve can maintain a lower temperature 
than the rest of the heating system, which may be used to separate 
underfloor heating system loops that use a lower temperature from 
radiators that operate at a higher temperature.
Mixing valve
The mixing valve is a valve that seamlessly mixes cooler closed circuit 
water with water from the heat source to reach the desired temperature. 
The mixing valve may be placed in a heating circuit or in a heat pump 
module as an external booster mixer.
3-way valve
The 3-way valve distributes heat either to the heating circuits or to the 
water heater. The valve has two fixed modes, hence the heating and 
DHW production cannot occur simultaneously. This provides for the 
most effective operation, since DHW is always heated to a specific 
temperature, while the heating water temperature is adjusted 
continuously according to current outdoor temperature.
External booster heater
The external booster is a separate heat source, which is connected to the 
heat pump module with pipework. The heating from the booster is 
regulated via a mixing valve, and is therefore also called a mixing valve 
booster. The user interface manages the booster on/off based on the 
current heating requirements. The heat source is either an electric, oil or 
gas boiler.
Heat transfer circuit
The part of the heating system that transfers heat from the heat pump to 
the heat pump module.
Cooling circuit
Cooling is disabled in the UK model to comply with 
the regulations for RHI.
The main part of the heat pump, which retrieve energy from outside air 
and transfers it as heat to the heat transfer circuit. Consists of 
evaporator, compressor, condenser and expansion valve. The 
refrigerant circulates in the cooling circuit.
Evaporator
A heat exchanger between air and refrigerant. The energy in the air, 
which is sucked up through the evaporator makes the refrigerant boil 
and turn into gas. 
Compressor
Makes the refrigerant circulate in the coolant circuit, from the 
evaporator to the condenser and back. Increases the gaseous 
refrigerant pressure. When the pressure increases, the temperature 
increases too.
Condenser
Is a heat exchanger between the refrigerant in the cooling circuit and the 
water in the heat transfer circuit. When heat is transferred, the 
refrigerant temperature decreases as it is condensed into a liquid.
Expansion valve
Decreases the refrigerant pressure when it comes from the condenser. 
The refrigerant is then transferred back to the evaporator, where the 
process starts over.
Inverter
Is found in the heat pump and enables RPM control of the compressor 
according to current heating requirements.
Setback phase
A time slot during automatic mode, with Setback operating mode.
Automatic mode
The heating system is heating in accordance with the time program and 
an automatic changeover takes place between operating modes.
Operating mode
The operating modes for heating are: Heating and Setback. These are 
indicated by the symbols and .
The operating modes for water heating are: DHW, DHW reduced and 
Off.
It is possible to set a temperature for each operating mode (except Off).
Frost protection
Depending on the selected frost protection, the heat pump will turn on 
when the outside and/or room temperature reaches below a certain set 
threshold. Frost protection prevents the heating system from freezing 
up.
Required room temperature (also desired or set temperature/set 
room temp.)
The room temperature to be achieved by the heating system. It can be 
set individually.
Default setting
Values permanently saved in the programming unit (e.g. complete time 
programs) that are available at any time and that can be reinstated 
according to demand.
Heating phase
A time slot during automatic mode, with Heating operating mode.