STULZ glossary - The A to Z of air conditioning


A B C D E F G H I J K L M N O P Q R S T U V W X Y Z


A

Humidification
Adiabatic humidification
Technical term for humidifying systems that manage without external, primary heat energy. The water is atomised in a fine mist and absorbed by the air.

back  top

Air Conditioning
Air handling technology
Air-conditioning systems belong to the field of air handling technology. Air handling technology is dedicated to controlling the climate in closed rooms.

back  top


B

Air Conditioning
BMS – Building management system
Building management systems (BMS for short) represent the management level of building automation and as such control and monitor building services. In modern air-conditioning systems, the control software has open interfaces to communication standards for building management systems, such as OLE for Process Control (OPC), Building Automation and Control Networks (BACnet) and Local Operating Networks (LON).

back  top


C

Comfort Air Conditioning
Cassetteria unit
Cassetteria units are a possible type of indoor unit. They have the appearance of a ceiling panel and can be integrated in coffered ceilings.

back  top

Comfort Air Conditioning
Ceiling unit
Ceiling units are one of the possible designs of indoor units for comfort air conditioning. They are fitted visibly beneath the ceiling.

back  top

Precision Air Conditioning
Chiller, Chilled water generator
Chillers (or chilled water generators) produce cold water for CW air-conditioning systems (see 'Cooling systems'). Chillers function on the basis of the DX principle (see 'DX'). Heat is dissipated by means of an air or water-cooled condenser. With a suitable control system and the integration of free cooling, large heat loads, in particular, can be cooled especially effectively using chillers. Another important advantage is that chillers are compact and come ready for connection.

back  top

Air Conditioning
Cooling capacity
The cooling capacity indicates the extent to which your air conditioner can cool the room. In other words, it specifies the maximum amount of heat the unit can take in and convey to the outside. Cooling capacity is measured in kilowatts (kW).

back  top

Precision Air Conditioning
Cooling system
Technical method of generating cold. STULZ precision air-conditioning systems are available with the following cooling systems:
  • A: Cooling system based on the DX principle, in which the heat removed from the room is discharged via an air-cooled condenser.
  • G: Cooling system based on the DX principle, in which the heat removed from the room is discharged via an air-cooled plate-type condenser in the air conditioner.
  • GE: Hybrid cooling system, comprising a DX system with integrated indirect free cooling.
  • CW: Cooling system in which the heat from the room is absorbed by a water-cooled direct cooling unit (CW 2 has two redundant refrigerant circuits).
  • ACW: Two independent cooling systems (CW and A) in one air conditioner. If the main cooling system (CW) fails, the A system ensures that air conditioning continues without interruption.
  • GCW: Two independent cooling systems (G and CW) in one air conditioner. If the main cooling system (CW) fails, the G system ensures that air conditioning continues without interruption.


back  top


D

Precision Air Conditioning
DFC - Dynamic Free Cooling
DFC is a control concept for the GE cooling system developed exclusively for the CyberAir 2, STULZ’s hybrid precision air-conditioning system. The DFC automatic air-conditioning system ensures precise and efficient interior climate control with minimal energy consumption. DFC combines compressor cooling and free cooling in four stages in all, and automatically searches for the most economical operating mode: when the outside temperature is low, DFC cools with thrifty indirect free cooling, whereby the energy-intensive compressors remain switched off. If the outside temperature rises, DFC first selects extended free cooling mode, then switches the compressors on step by step. With the help of standby units, the automatic control balances all the various units in energy-saving partial load mode.

back  top

Precision Air Conditioning
Direct free cooling
Air-conditioning systems with direct free cooling use cold outside air for cooling when outside temperatures are low. The incoming flow of air is regulated by an air flap. When the outside temperature rises, the air-conditioning system gradually switches to compressor cooling (mixed mode) and then to pure closed-circuit cooling (DX mode), in which the air is simply recirculated internally. Energy consumption is considerably higher in closed-circuit mode, which is why it is only employed on especially hot days. Direct free cooling is used in ICT facilities with lower heat loads – in base stations for mobile phone networks, for example (also see 'Indirect free cooling').

back  top

Comfort Air Conditioning
Duosplit
"Duosplit" means that two indoor units are connected to one outdoor unit.

back  top

Precision Air Conditioning
DX – Direct Expansion
Traditional compressor-type air-conditioning system, which generates cold via a closed refrigerant circuit with an evaporator, compressor, condenser and expansion valve. The evaporator evaporates the refrigerant, absorbing heat as it does so. The compressor sucks up the refrigerant gas and compresses it under high pressure. The refrigerant becomes liquefied again in the condenser, emitting heat in the process. The expansion valve allows the refrigerant to expand, and the cycle starts again from the beginning. We distinguish between different cooling systems depending on the type of condenser (also see 'Cooling systems').

back  top


E

Air Conditioning
Efficiency
The efficiency indicates how much cold or heat energy the air-conditioning system is producing from the energy used (electricity or gas). Professionals recognise the level of efficiency from the COP value. Devices with energy efficiency class A, for example, have a COP of at least 3.2; in other words, they produce a cooling capacity of at least 3.2 kW from 1 kW of electrical power. In partial load, the COP even achieves between 4 and 5, as the power input is even lower in relation to the output.

back  top

Air Conditioning
Energy efficiency class
Many consumers are already familiar with energy efficiency classes from washing machines and other household appliances. The energy efficiency class indicates the efficiency with which your air conditioner converts electricity into cooling power. The less electricity is used to generate a given cooling capacity, the more economical and ecological the air conditioner is in terms of energy. The classes range from A to G. Class A means that the air conditioner is especially energy efficient.

back  top


F

Comfort Air Conditioning
Floor standing units
Floor standing units are a possible design of indoor unit, which are also referred to as chest units and are installed like a radiator.

back  top


H

Air Conditioning
Heat pump
A heat pump is an additional option in high-quality air-conditioning systems. These systems can heat as well. The heat pump reverses the principle of cold generation: the "refrigerant" removes heat from the outside and conveys it to the inside. On mild winter days and other in-between times, heat pumps are a valuable, cost-efficient alternative to conventional heating, e.g. for weekend retreats and holiday apartments.

back  top

Humidification
Humidifier
Humidifying systems control the air humidity. They safeguard production processes, preserve materials, prevent static electricity and ensure that people in closed rooms can breathe healthy air. Depending on the system used, humidifiers produce either hot steam (isothermal humidification) or a cold mist from energy-efficient atomisation (adiabatic humidification).

back  top

Comfort Air Conditioning
Hybrid
Term designating a bivalent air-conditioning system, in which air conditioners and a conventional heating system work in combination. ‘Hybrid’ is a term that is also becoming popular in the automotive industry to indicate vehicles powered by a combination of electricity and petrol. In the automotive industry, hybrid vehicles are seen as the environmentally friendly alternative to diesel.

back  top


I

Precision Air Conditioning
Indirect free cooling
In contrast to direct free cooling, in which “direct” use is made of outside air for cooling, indirect free cooling transfers the cold by means of a pipe system containing a water-glycol mixture. A recooling heat exchanger cools the mixture with outside air. Air-conditioning systems with indirect free cooling can be configured with great flexibility, and are especially energy efficient (also see 'Direct free cooling').

back  top

Comfort Air Conditioning
Indoor unit
The indoor unit is the interior part of a split air conditioner. It is installed in the room that is to be air-conditioned, and connected to the outdoor unit via a refrigerant pipe. Indoor units are available in numerous designs: as floor standing types, wall or ceiling-mounted units or models for installation in ducts.

back  top

Comfort Air Conditioning
Inverter technology
Simple air conditioners are controlled solely by thermostat. Once the selected temperature is reached, the unit switches off. If it is exceeded, it switches on again. In units with inverter technology, the speed of the compressor is infinitely adjusted, i.e. the unit slows down gradually before stopping, and restarts slowly, too. This enables a more constant room temperature to be maintained and, in addition, units with inverter technology use less energy.

back  top

Humidification
Isothermal humidification
Technical term for humidifying systems that produce steam by heating water.

back  top


M

Comfort Air Conditioning
Monosplit
Monosplit is a type of split air conditioner. "Monosplit" means that each indoor unit works in conjunction with an outdoor unit.

back  top

Comfort Air Conditioning
Multisplit
Multisplit is a type of split air conditioner. With multisplit systems, several indoor units are connected to one outdoor unit.

back  top


O

Comfort Air Conditioning
Outdoor unit
The outdoor unit is the exterior part of a split air conditioner. It also houses the compressor.

back  top


P

Precision Air Conditioning
Power Usage Effectiveness (PUE)
The international IT consortium "The Green Grid" uses PUE to deliver a cross-border comprehensive approach in determining the total energy efficiency of a data centre. This index has become a globally recognised standard and serves to highlight the success of optimisation processes which reduce the energy consumption of data centres. PUE is calculated by dividing the total power consumption of the data centre (in kW/h) by the IT equipment consumption (servers, storage systems and network hardware). The figure that results from this calculation is generally known as the PUE value and should be somewhere between 1.0 and 2.0. A value of 2 means that the operation of air conditioning and UPS equipment (physical infrastructure) consumes twice as much energy as the IT equipment used (IT load).

back  top

Precision Air Conditioning
Precision air-conditioning systems
Highly specialised air-conditioning systems, adapted to the requirements of information and communication technology. Precision air-conditioning systems keep the room temperature constant to the last degree, precisely regulate the relative air humidity, filter the air and distribute the cooled air around the room thoroughly and evenly. They are designed for failure-free continuous operation – 24/7, 365 days a year. In contrast to conventional comfort air conditioners, precision air-conditioning systems have a considerably better ratio of total cooling capacity to sensible cooling capacity – in other words, up to 100 % of the energy consumed is utilised to cool the room temperature.

back  top


Q

Comfort Air Conditioning
Quattrosplit
"Quattrosplit" means that four indoor units are connected to one outdoor unit.

back  top


R

Air Conditioning
Recooling heat exchanger
Ready-to-connect air/water heat exchanger for cooling water-glycol mixtures. The brazed plate heat exchanger of the air conditioner and the externally fitted recooling heat exchanger are connected via a closed water-glycol circuit. The recooling heat exchanger discharges the heat from the mixture into the ambient air.

back  top

Air Conditioning
Refrigerant
The refrigerant is a standard component of every air-conditioning system. As a heat-transport fluid, it conveys the heat in the room from the indoor to the outdoor unit. Modern air-conditioning systems contain CFC-free refrigerant R 410 A or R 407 C. R 410 A also increases the efficiency of air conditioners and enables them to be especially compact in design. The refrigerant circulates in a closed circuit, and therefore cannot escape. During installation, a qualified cooling system engineer expertly fills your air conditioner with refrigerant and checks the system for leaks. If the unit has to be removed, the cooling system engineer siphons the refrigerant into recycling bottles for environmentally friendly disposal.

back  top

Air Conditioning
Refrigerant pipe
The refrigerant pipe is similar to a heating pipe. It connects the outdoor unit to one or more indoor units. The diameter and length of the refrigerant pipe vary depending on the air-conditioning system and the refrigerant used. Thanks to its high heat absorption, refrigerant R 410 A enables especially long, slim piping to be installed. In addition to the refrigerant pipe itself, the system has separate lines for the electrical control system and the removal of condensed water.

back  top

Air Conditioning
Remote control
High-quality air-conditioning systems can be controlled by remote control - both centrally and as individual units. Depending on the type of unit, remote controls can regulate the room temperature, mode (cooling, heating, ventilating, dehumidifying, automatic), fan stage and direction of air. Time switches are often incorporated for programming the output. Wired, infrared and central remote controllers are available, and can be operated via console, touchscreen, PC software or the Internet.

back  top


S

Air Conditioning
Sensible cooling capacity
The cooling capacity generated by air conditioners is partly latent, partly sensible. The sensible cooling capacity lowers the temperature, while the latent capacity dehumidifies the air. Comfort air-conditioning units use up to 50% of their energy for dehumidification, while precision units convert more than 95% of the energy used exclusively to cooling power. The technology required to achieve this pays off quickly through lower running costs.

back  top

Air Conditioning
Sound pressure level
The sound pressure level is stated in decibels, or dB(A), and is a measure of the running noise. The lower the value, the quieter your air-conditioning system is running. In particularly quiet room air conditioners, the sound pressure level is only slightly higher than the rustling of paper, at approx. 25 dB(A).

back  top

Comfort Air Conditioning
Split air conditioners
With split air conditioners, at least one outdoor and one indoor unit work together (monosplit). The outdoor unit generates the cold (condenser). The refrigerant, which conveys the heat, circulates in a closed piping circuit between the indoor and outdoor units. The indoor unit (evaporator) removes the heat from the room. Several indoor units can be connected to one outdoor unit (multisplit).

back  top


T

Air Conditioning
Thermostat
The thermostat switches the air-conditioning system on or off as the temperature becomes too high or too low. In especially sophisticated air-conditioning systems, the thermostat is replaced by energy-saving inverter technology. In this case, the air-conditioning system is not simply switched on and off, but regulated gradually by the ramped slow-down and acceleration of the compressor.

back  top

Comfort Air Conditioning
Triosplit unit
"Triosplit" means that three indoor units are connected to one outdoor unit.

back  top


V

Comfort Air Conditioning
VRF – Variable Refrigerant Flow
With this technology, the intelligent compressor control continually regulates the flow of refrigerant as a function of the required output.

back  top


W

Comfort Air Conditioning
Wall-mounted units
Wall-mounted units are a possible type of indoor unit. They are mounted suspended on free areas of wall.

back  top