Specialist terminology explained
Glossary
The acoustic power level quantifies all the energy emitted by an object as noise. This value is dependent on location, space, and distance. It can be used for comparisons with other ventilation units, whereas the sound pressure level cannot
A building can be cooled with the active cooling function. The heat pump needs to be reversible for the active cooling, which means the cooling circuit runs in reverse. Here, the heat is emitted into the outside air from the building using the heat pump. During this process, the compressor of the heat pump runs (is active).
An actuator is an electric controller / control unit or small motor that automatically regulates the flow of heating water. It is usually fitted to the valve of a heating circuit manifold and opens or closes the relevant heating circuit in accordance with the settings on the room thermostat.
Actuators are primarily used in panel heating systems such as underfloor heating. They enable the room temperature to be regulated according to demand and contribute to the energy-efficient and comfortable operation of the heating system.
Designer radiators with additional electric operation are connected to the central heating network but can be operated independently of it from an electrical perspective. This is particularly suitable in transitional periods and for short-term heat demand. More information on electric operation of designer and bathroom radiators.
The air filter is a component of a ventilation system or the indoor unit of an air-conditioning system. It filters dust, dirt particles and other contaminants from the room air, thereby helping to improve air quality.
It is important to clean or perform the replacement of the air filter regularly to ensure that the system operates hygienically, efficiently and reliably. This maintains air circulation and supports the system’s performance.
The air vent plug seals the heating system in relation to the outside world. It can easily be removed to bleed the radiator.
The air volume flow rate describes the quantity of air that a unit moves per unit of time. It is usually expressed in cubic metres per hour (m³/h) and is an important parameter for the performance of ventilation and air-conditioning systems.
A correctly sized air volume flow rate ensures an adequate air supply, efficient distribution of heat or cold, and a comfortable indoor climate. In ventilation systems, it also helps to reliably extract stale air and supply fresh air.
Radiators with all-electric operation are independent of the central heating network; in this case, a socket is the only energy connection required for the installation. Especially in old buildings, they are a time and cost-saving solution for modernisation projects. But even in energy-autonomous new builds with solar panel systems, an electric radiator can provide a way of utilising the self-produced electricity. More information on our electric radiators.
If the funding for replacing the heating system is approved by BAFA, it triggers the start of the approval period. During these 12 months, the funded measures are implemented. If the measures are delayed, there is the possibility of extending the deadline.
The automatic defrost function is a feature of heat pumps and air conditioning units that automatically detects and removes ice build-up on the outdoor unit. To do this, the refrigeration cycle is briefly reversed so that the heat exchanger is heated and the ice is reliably defrosted.
Automatic defrosting ensures that the system operates efficiently even at low outdoor temperatures and reliably maintains its heating capacity. This reduces energy losses and supports safe, durable operation.
Firstly, the German Federal Office of Economics and Export Control (BAFA) plays an administrative role in the areas of foreign trade, energy business promotion, and auditor supervision. Secondly, it also promotes energy-efficient technologies and energy-saving measures.
A blanking plug seals the heating system in relation to the outside world and hides the opening behind it. It can easily be removed for maintenance work. Blanking plugs are included in the delivery of our radiators.
The BTU (British Thermal Unit) is a unit commonly used internationally to specify the cooling and heating capacity of air-conditioning systems. Particularly in an international context, split-type air-conditioners are often specified in BTU/h (BTU per hour) rather than in kilowatts (kW).
To facilitate comparison, capacity is predominantly stated in kilowatts (kW) in Europe. The BTU specification therefore serves primarily as a guide when comparing international products and technical data.
The buffer charging pump moves the heat generated by the heat pump to the buffer or domestic water tank.
The capillary tube is a simple expansion device in a refrigeration circuit. It reduces the pressure of the refrigerant before it enters the evaporator, thereby enabling the phase change required for the cooling or heating process.
A distinction is made between the following:
- A centrally arranged central system where one ventilation unit is responsible for supplying several housing units.
- A decentrally (semi-centrally) arranged central system where one ventilation unit is responsible for supplying a housing unit with air and the air is then delivered to the respective rooms by means of ducts.
With a centre connection, the flow and return pipelines are located centrally on the underside of the radiator. This allows the pipelines to be routed centrally, regardless of the radiator’s width.
This type of connection simplifies planning and installation in both new builds and refurbishment projects. At the same time, it ensures a clean, neat appearance and offers a high degree of flexibility when selecting and performing the replacement of radiators.
Dust formation inside radiators is a natural process that is linked to the circulation of the warmed air and cannot be prevented by technical means. Accessible locations should be cleaned periodically with special brushes to ensure optimal heat output. Radiators can be easily cleaned with our special brushes.
You can buy these products from your qualified specialist installer, from specialist wholesalers, or can order them online from our KERMI spare parts shop from the convenience of your own home. To find a specialist partner near you, please refer to our Specialist partner overview.
You can also clean your radiator with household cleaning agents. Cleaning agents used on paint surfaces should not be abrasive. Nor should they be strongly alkaline or acidic (chemically aggressive).
To be able to clean the radiator properly, you first have to remove the top cover. To do this, you need to lift the plastic clip (KERMI clip, can also be ordered from online shop) on the side panel and unscrew anticlockwise. With Plan radiator lengths of 1000 or more or with a radiator length of 1400, the Profil radiator retaining bar also needs to be removed from the top cover. After that, pull the side cover off the radiator at a slight angle, lift the top cover, and detach the side cover from the fixing hooks. Then separate the top cover from the second side cover by lifting it at one side and sliding it. After cleaning, reinstall the top cover by following the steps in reverse order!
Within the framework of the Climate Protection Act, the federal government in Germany has adopted measures that aim to achieve greenhouse gas neutrality by 2050. The programme includes a package of CO2 saving measures for the energy sector, industry, buildings, transport, agriculture and forestry, land use, and waste management. By 2030, Germany intends to reduce its CO2 emissions by at least 55 percent.
CO2 emissions means the greenhouse gases produced by the combustion of substances such as coal, diesel, petrol, natural or liquid gas, and wood. The CO2 generated during the combustion process accumulates in the atmosphere and is largely responsible for the greenhouse effect and global warming.
A compact radiator is a classic panel radiator with side connections. Inside, integrated convection fins ensure that heat is efficiently transferred to the room. Heat is transferred via both radiant heat and convection.
Compact radiators are popular due to their high heating capacity, simple installation and versatility. They are available in various heights, lengths and versions and can be adapted to a wide range of room layouts.
The compressor is a key component in the refrigeration cycle of heat pumps and air-conditioning systems. It compresses the gaseous refrigerant, thereby increasing its pressure and temperature.
As the ‘driving force’ of the refrigeration cycle, the compressor ensures that the refrigerant circulates continuously between the individual components, allowing heat to be absorbed or released. Modern technologies such as inverter technology enable the compressor’s output to be adjusted to meet demand, thereby supporting efficient and comfortable operation.
Condensation is water that forms when moist air cools on a cold surface – for example, on the evaporator of an air-conditioning unit. During this process, the moisture contained in the air is released as water.
In air-conditioning units, the resulting condensation is deliberately drained away to ensure safe and hygienic operation. Proper condensate drainage helps to prevent moisture damage and ensure the reliable functioning of the system.
The condenser is a heat exchanger in the refrigeration circuit of heat pumps and air-conditioning systems. Here, the refrigerant releases the heat it has absorbed into the environment or the heating system, changing in the process from a gaseous to a liquid state.
In a heat pump’s heating mode, for example, the heat is transferred to the heating water, which is then distributed throughout the building via radiators or panel heating systems. The condenser is therefore a key component for efficient heat transfer within the system.
The current series of numerous KERMI radiators have a uniform 50 mm centre connection standard, which allows complete freedom of planning and decision-making with regard to the radiator model, type, length and height right up to the final stage. In many radiators with a centre connection, the connection is completely concealed within the radiator or under a cover for the connection screw. The classic variants, with the connection on the left or right at the bottom or on the side, are also available for many models. Further information on KERMI connection types can be found in the technical documentation for the respective product.
Convection refers to the heat transfer through the movement of air. When a radiator heats the surrounding air, it rises, whilst cooler air flows in to replace it and is also heated. This creates a continuous circulation of air that distributes the heat throughout the room.
Many traditional radiators release most of their heat via convection. Surface heating systems, such as underfloor or wall heating, on the other hand, rely predominantly on radiant heat and only to a small extent on convection. This results in less air movement, which contributes to a more even heat distribution.
Cooling output describes the amount of heat that an air-conditioning system can remove from a room per unit of time. It is usually expressed in kilowatts (kW) and indicates how much cooling power a unit can provide under specific conditions.
Selecting the correct cooling output is crucial for efficient operation and a comfortable indoor climate. If the output is optimally matched to the room and its intended use, the air-conditioning system can operate energy-efficiently and ensure comfortable temperatures.
The coefficient of performance (COP) is a relevant key figure for the efficiency of a heat pump. The value indicates the ratio between the heat generated (heating capacity) and the electrical energy consumed (electricity). The higher the COP value, the more efficiently the heat pump works
The COP is determined under standardised conditions. In addition to the COP itself, the temperature of the energy source and the flow temperature used to determine the COP are also stated. The first-mentioned value is indicated with the letters A, B and W. These stand for the English terms for air (Air), brine (Brine) and water (Water). The second value indicates the flow temperature (W) of the heating system.
For example, a COP value of 4.96 (A2/W35) for an air/water heat pump means that at an air temperature of 2° Celsius (=A2) and a flow temperature of 35° Celsius (=W35), one kilowatt (kW) of electrical energy produces 4.96 kW of heating capacity.
In many buildings, radiators are exposed to special conditions which can attack the coating. The KERMI anti-corrosion coating is a special layer which is applied directly to the radiator and is then finished with a high-quality powder coating. It protects the radiator from damage caused by moisture and can also be applied under coloured paint finishes.
Radiator covers serve two purposes. Firstly, they protect the inside of the radiator from dirt and, secondly, they are responsible for directing the air flow from the radiator. If the cover is missing, warm air can escape in undesired directions and optimum distribution in the room is no longer ensured.
Cover rosettes are used to conceal unwanted connections or fixings and thus also protect against dirt.
You will find top and side covers for radiators as well as cover rosettes for radiator connections and fixings in our KERMI spare parts shop.
Are you looking for a nearby specialist partner so you can see our products in the flesh, get some advice, or place an order? To find a specialist partner near you, please refer to our Specialist partner overview.
As a general rule, decentralised ventilation units with heat recovery only work in individual rooms and are usually operated without a duct system. However, in some cases, a second room is connected to the unit via a pipe system.
Dehumidification mode (Dry Mode) is an operating mode for split air-conditioning systems in which excess moisture is removed from the room air. Unlike normal cooling operation, the primary aim here is not to lower the room temperature, but to reduce the humidity.
A lower humidity level ensures a more pleasant indoor climate and increases comfort – particularly on warm, humid days. At the same time, the air conditioner operates particularly energy-efficiently in dehumidification mode, as only a low cooling output is required.
The control deviation describes the difference between the setpoint (desired temperature) and the actual value (temperature actually measured) in a control system. It serves as the basis for thermostats or control systems to automatically adjust the flow of heating water.
The smaller the control difference, the more precisely the heating control system operates. This ensures a constant room temperature, increases living comfort and supports energy-efficient operation of the heating system.
A direct evaporation system is a refrigeration or air-conditioning system in which the refrigerant evaporates directly in the evaporator of the indoor unit. In doing so, it extracts heat from the room air, thereby cooling the room efficiently.
Direct evaporation systems are primarily used in split-type air-conditioning systems. They are characterised by rapid cooling output, high efficiency and a compact construction method.
An EC motor (electronically commutated motor) is a brushless DC motor which takes the form of a three-phase synchronous motor and is excited by permanent magnets. The rotary field is achieved through integrated commutation electronics (reversal of current). A magnetic rotary field is generated in the stator coil by the three-phase supply, which induces a magnetic field in the rotor that then leads to rotation. The advantages are the extremely high efficiency and the infinitely adjustable speed control via the commutation electronics.
The European Union’s Ecodesign Directive sets out requirements for the environmentally sound design of energy-related products. The aim is to improve their energy efficiency and sustainability right from the development stage. Manufacturers must design their products in such a way that, throughout their entire life cycle, they are as resource-efficient, durable and energy-efficient as possible.
Electric radiators are also subject to the provisions of the Ecodesign Directive. The requirements, which come into force on 1 July 2025, ensure that appliances consume less energy, thereby helping to reduce operating costs and CO₂ emissions. For consumers, this means modern, efficient heating solutions that combine comfort with sustainability.
The EER (Energy Efficiency Ratio) is a measure of an air-conditioning system’s energy efficiency in the cooling operation. It describes the ratio between the cooling output and the electrical power consumption required to achieve it.
The higher the EER value, the more efficiently the unit operates under the specified test conditions. With modern split-system air-conditioning units, the SEER (Seasonal Energy Efficiency Ratio) is now frequently used to compare energy efficiency, as it takes into account the unit’s performance over an entire cooling season.
The efficiency describes the ratio of useful energy to supplied energy. The higher the efficiency, the more efficiently the unit is working.
The electronic expansion valve (EEV) regulates the amount of refrigerant flowing into the evaporator of an air-conditioning system or heat pump. Thanks to its precise control, it continuously adjusts the refrigerant flow to match the current demand for cooling or heating.
As a result, the system operates particularly efficiently, responds quickly to changes in load and ensures energy-optimised operation as well as a high level of comfort.
The height difference names the difference in height between two components of a system. In split air-conditioning systems, it names the maximum permissible height difference between the indoor and outdoor units.
The height difference specified by the manufacturer must be taken into account during planning and installation, as it affects the system’s proper functioning, efficiency and operational safety.
The energy efficiency class indicates how energy-efficient an appliance is (e.g. A+++ to D). The classification is awarded in accordance with EU guidelines and makes it easier to compare different products in terms of their energy consumption.
Depending on the product group, the classification is based on different test procedures and efficiency metrics. A high energy efficiency class indicates economical operation and can help to reduce energy consumption and operating costs in the long term.
On the basis of the Energy Saving Act, the Energy Saving Ordinance (EnEV) sets standard requirements for privately and commercially used new builds, such as apartment buildings, office blocks, etc. This is to ensure that construction projects are built in an energy-efficient way. It is part of German commercial administrative law.
In contrast to normal heat exchangers, enthalpy heat exchangers can also recover moisture. In the winter, this has the advantage of slowing down the natural drying-out process that occurs in living spaces. This can help to increase the moisture within the living space to a more comfortable level. Particularly at cold times of the year, it is – of course – important to adjust the air flow in line with the actual demand, to reduce the air flow and to prevent the rooms from overheating (temperatures of 23 °C and above) with a view to keeping the humidity at >35 %.
An EPD (Environmental Product Declaration) documents the environmental impact of a product throughout its entire life cycle. It is based on international standards and provides a transparent, comparable basis for sustainable construction and building certification.
Various products from the KERMI range have been EPD-verified – for example, in the areas of steel radiators and underfloor heating. This enables specialist partners to demonstrate the environmental performance of the products used in tenders and grant-funded projects.
You can find further information on the EPD verification of our products here.
The evaporator is a heat exchanger in the refrigeration circuit of heat pumps and air-conditioning systems. Here, the refrigerant absorbs heat from the surroundings and evaporates in the process.
In the cooling operation of an air-conditioning system, the evaporator extracts heat from the room air, thereby cooling the room. In heat pumps, for example, it absorbs heat from the outside air, thereby providing the basis for efficient heat generation.
From 2026 onwards, no pure oil heating systems are allowed to be installed in new builds. From that point, it will only be permissible to install regenerative systems or to use hybrid systems that rely on renewable energies in addition to oil to generate heat. The German government’s new climate package has comprehensively updated and expanded the market incentive programme. This subsidy is also known as the exchange bonus.
The extract air is the name given to the used and contaminated air (odours, humidity, CO2 or other volatile organic gases) which are to be removed from the living space.
The F-Gas Regulation is an EU regulation aimed at the gradual reduction of fluorinated greenhouse gases (F-gases). The aim is to reduce the use of climate-damaging refrigerants and to promote the switch to more environmentally friendly alternatives.
The Regulation applies, amongst other things, to heat pumps, air-conditioning systems and refrigeration systems. It regulates, for example, the use of certain refrigerants as well as requirements for installation, maintenance and leak tests, thereby contributing to the more climate-friendly operation of modern indoor climate control systems.
Filters can be divided into outside air filters and extract air filters.
The outside air filter ensures that the supply air coming into the house is clean and fresh. It prevents fine dust and pollen – as well as spores, viruses, and bacteria – from getting into the building from outside. In addition to that, outside air filters protect installed components against soiling.
The used air is returned to the outside via the extract air filter. Dust and dirt particles are also filtered out of the extract air to prevent soiling of the unit. This ensures clean operation of the heat exchanger and the efficiency of heat recovery is maintained.
You can order original KERMI filters for your controlled residential ventilation system easily and conveniently from the KERMI spare parts shop.
The filter drier is a component in the refrigeration circuit of air-conditioning and heat pump systems. It removes moisture, dirt particles and other contaminants from the refrigerant before they can reach sensitive components.
In doing so, the filter drier protects the refrigeration circuit from damage, increases operational reliability and helps to ensure that the system continues to function efficiently and reliably over the long term.
The flow temperature refers to the temperature to which the heating water has to be heated before it flows through the heating system by travelling through radiators and underfloor heating.
There are special fastenings for flower boxes for flat radiators and convectors. You can find the fastenings in the technical documentation for the respective product. We do not stock flower boxes or similar covers ourselves.
You can also find fastenings for window sill supports online in our KERMI spare parts shop.
With brine/water heat pumps, the thermal energy is collected from the environment using a ground collector or ground probes and is converted into thermal heat. Geothermal collectors are generally laid horizontally at a depth of up to 2 m.
A geothermal probe collects thermal energy from the environment via one or more geothermal wells with a depth of up to 100 m. For that reason, they require a permit. The advantages compared to geothermal collectors are the significantly lower space requirements and higher source temperature over the year, which allows greater efficiency of the heat pump.
The Global Warming Potential (GWP) is a metric that describes the greenhouse potential of a refrigerant in comparison to carbon dioxide (CO₂). CO₂ serves as the reference value and has a GWP of 1.
The lower a refrigerant’s GWP value, the smaller its potential impact on the climate. For this reason, low-GWP refrigerants are increasingly being used in modern heat pumps and air-conditioning systems to reduce environmental impact and meet current legal requirements.
Most KERMI designer radiators are suitable for heating cost recording using a heating costs allocator. Evaporation counters can also be installed on steel panel radiators. As the positioning of the recording devices differs from one manufacturer to another, please contact the relevant manufacturer for details. You will find further information in our technical documentation for the respective product.
What should you do if only half of the radiator or only the top gets warm?
If only half of the radiator gets warm but the desired room temperature is reached, then there is no reason to worry. The thermostat controls the flow of water in such a way that this may happen to the radiator in case of partial quantities of water. However, if the radiator remains cold in the lower area and the room temperature drops or no longer rises, you should take action. There are many possible causes for a heating system not heating evenly and they range from trapped air to faulty pressure conditions in the heating system.
Air in the heating system: This can easily be solved by bleeding the radiator. All you need is a common bleed key, a bowl, and rag to catch any leaking heating water. If the radiator still does not heat up properly or the room temperature does not rise, check point 2.
Thermostatic valve: If the thermostatic valve has not been operated for a long time, the pin of the valve may jam. As a result, the right quantity of water no longer flows through the radiator and it only gets warm at the top. In this case, we recommend calling a specialist installer. They can remove the thermostatic valve and change the thermostat if necessary.
Hydraulic balancing: If the hydraulic balancing has not been carried out properly or if the heat supply in the building has changed due to structural measures, this can lead to the radiator only heating up at the top. If this is the case, we once again advise you to contact a specialist installer.
The problem can be resolved by using a KERMI radiator with x2 technology, which causes water to flow through the front panel first. The front panel becomes uniformly warm and the rear panel serves as a shield against the cold outer wall during partial load mode (90 % of the heating period).
Further information on our therm-x2 radiators. To find a specialist partner near you, please refer to our overview.
A heat exchanger transfers heat from one medium to another without the two media mixing. In heating, cooling and ventilation systems, it ensures that heat is used efficiently and transported to where it is needed.
In heat pumps, the heat exchanger plays a central role: it extracts heat from the environment – for example, from the air, the ground or groundwater – and transfers it to the building’s heating system. This enables energy-efficient heating and hot water production. Depending on the range of applications, different types of heat exchangers are used, each tailored to the specific requirements in terms of performance, efficiency and space requirements.
The heat output of a radiator depends on various factors, such as the flow temperature, the size, and the design. If, for example, the flow temperature is very low, a larger radiator should be selected but there are also radiator versions that deliver considerably more output for the same size. The different versions are divided into the following types: 10, 11, 12, 20, 21, 22, and 33. The larger the number, the deeper the radiator. The first digit always indicates the number of heating plates and the second the number of convectors.
You can find the exact heat output of our radiators in the technical information for the relevant product in our download area. When determining the heat output, make sure you select the temperature pairing correctly. Determination of the standard heat output according to EN 442 is based on temperature pairing 75/65/20 °C. In practice, lower temperatures are commonly used nowadays.
Please contact your specialist installer for a precise calculation.
Heat recovery describes the process of making energy reusable. Let’s take the ventilation system as an example. Here, the thermal energy of the extract air is emitted to the outside air via a heat exchanger. The proportion of heat recovered is expressed based on the degree of heat recovery or the amount of heat made available (efficiency).
The heating load of a building specifies how much thermal energy needs to be introduced into the building to achieve the ideal indoor climate despite the losses that are bound to occur – e.g. through doors and windows.
Hot-dip galvanising is a process used to provide long-lasting anti-corrosion protection for steel. The component is immersed in molten zinc, creating a durable protective layer that reliably protects the steel from rust.
Hot-dip galvanised radiators are particularly suitable for areas with high levels of moisture load or demanding environmental conditions. The additional protective layer increases durability and contributes to long-term, safe operation.
A hybrid system is one that combines different heat generation technologies. Classic energy sources such as oil or gas are frequently linked to renewable energy sources, thereby allowing the strengths of two different heating systems to be combined.
To ensure that the heating system works without any problems, the volume flow of the heating water needs to be adjusted to the heat demand of every individual radiator. KERMI valve radiators are preset at the factory according to the standard heat output of the radiator. This saves energy costs and ensures optimal thermal comfort. Further information on valve technology & hydraulic balancing.
The jury of the International Forum Design in Hanover is a panel of experts from all over the world. Every year, they honour everyday products that stand out from the crowd because of their form and function with the iF DESIGN AWARD – one of the most important and prestigious design competitions worldwide. The iF DESIGN AWARD has been around for more than 60 years now. Companies from across the world register their innovative products to participate in this competition. Over three days, an expert jury of more than 50 people undertakes the mammoth task of assessing the 5000 to 6000 products that are competing against each other for the highly sought after award in the category “Product/Packaging”.
Many of our designer and bathroom radiators have already won the prestigious iF Design Award. They include:
The indoor unit of a split-system air-conditioning unit in a room, which draws in air, cools or heats it, and blows it back out.
An infrared radiator is an electrically operated radiator. It provides a high proportion of cosy and efficient radiant heat. that feels like warm sunshine, quickly and directly affecting the human body as well as any other surfaces it irradiates. The high proportion of radiant heat minimises air movement and dust dispersion. This makes infrared radiators particularly attractive to allergy sufferers.
Inverter technology is regulation technology in which the compressor’s speed is continuously adjusted to match the actual power requirement. Instead of repeatedly switching on and off, the compressor operates continuously at the power level required at any given time.
This reduces energy consumption and noise levels, maintains the desired room temperature constantly and minimises wear and tear on components. Inverter technology is now used in many modern heat pumps and split-system air conditioners, contributing to particularly efficient and comfortable operation.
KERMI Clips are used to fix the side covers of the radiator in place. These are included as standard with each radiator that comes with attachable side covers. However, if you need a replacement, you can conveniently order the KERMI Clip online from our KERMI spare parts shop .
The German Reconstruction Loan Corporation (Kreditanstalt für Wiederaufbau (KfW)) is one of the leading business development banks worldwide. With their range of funding programmes, they support developers in various ways, e.g. by assisting them with the purchase of residential property and with energy and resource-efficient construction. Many KERMI products are eligible for KfW funding.
The kv value is also referred to as the flow factor or flow coefficient and is a measure of the flow of a liquid or gas that can be achieved through a valve. It is used for selecting and dimensioning valves, and corresponds to the water flow through a valve (in m³/h) with a pressure difference of 1 bar and a water temperature of 5–30 °C.
A leak test is carried out to check refrigerant pipes and components for leaks. It ensures that no refrigerant escapes and that the air-conditioning unit operates reliably and efficiently.
A leak test carried out professionally contributes to the operational safety, energy efficiency and durability of the system. Depending on the refrigerant and charge quantity, regular tests may also be required by law.
A low temperature radiator is specifically designed for heating systems with low flow temperatures, such as those provided by heat pumps. Thanks to optimised heat transfer, it achieves a high heating capacity even at lower flow temperatures, thereby contributing to the energy-efficient operation of the entire heating system.
With the x-flair heat pump radiator, we offer a solution developed specifically for use with heat pumps. Thanks to an integrated fan system, it ensures a high level of thermal comfort even at low flow temperatures and is ideal for both new builds and refurbishments.
In order to focus on CO2 savings in the construction industry, a market incentive programme has been in place for almost 20 years. The market incentive programme has been updated and widely extended as part of the Climate Protection Package 2030. This subsidy programme creates incentives to generate heat from technology based on renewable energies. This includes, for example, installing heat pumps, replacing old oil heating systems, or using hybrid systems.
In the case of a standard wireless local area network, the reception is distributed throughout the home by an individual device: the router. By contrast, a mesh network is established by placing various access points all around the living area.
A modulating (power controlled) heat pump can adapt its heat output to the heat demand of a building. This allows the heat pump to work more quietly and more efficiently, and optimally adapt to different outside temperatures.
Humidity recovery is a feature of modern ventilation systems whereby some of the humidity from the warm extract air is transferred to the fresh supply air. This ensures that more humidity is retained indoors, particularly during the heating period, without the supply and exhaust air mixing.
This ensures a more pleasant indoor climate, prevents the room air from becoming too dry and enhances living comfort. At the same time, occupants continue to benefit from a controlled supply of fresh air and energy-efficient ventilation.
Find out more about our residential ventilation systems here.
An air-conditioning system with several indoor units connected to a single outdoor unit.
Sleep mode is an operating mode for air conditioning systems in which the noise level is reduced and the temperature control is adjusted to suit the needs during sleep.
By reducing fan speed and optimising control, night mode ensures particularly quiet yet energy-efficient operation.
An on/off air conditioner is an air conditioning unit in which the compressor operates exclusively in either the ‘on’ or ‘off’ state. Unlike units with inverter technology, the output cannot be continuously adjusted to actual demand.
Once the room temperature reaches the desired level, the compressor switches off and starts up again when cooling is required once more.
With the one-pipe system, the flow and return are connected to the same line. This means that the water first flows through the first radiator and heats it, then it continues to flow into the second radiator. The return temperature of the first radiator in the line is therefore the flow temperature of the second radiator, etc.
Adjustable operating mode of an air-conditioning system, e.g. cooling, heating, dehumidification or ventilation.
As an end customer, you can purchase our products from your qualified specialist installer. They will be glad to draw up a quotation for you.
To find a specialist partner near you, please refer to our overview.
In addition, you will also find spare parts and accessories for your radiator or your residential ventilation in our KERMI spare parts shop , which you can order online from the comfort of your own home.
A component of a split-system air-conditioning unit that is installed outside the building and contains the compressor, condenser and fan.
The air that flows in from outside.
You can use our touch-up pen or our spray can to repair minor paint damage to radiators. Both are available in the colour RAL 9016 (White). You can buy these products from your qualified specialist installer, from specialist wholesalers, or can order them online from our KERMI spare parts shop from the convenience of your own home.
A building can be cooled with the passive cooling function. During passive cooling, the compressor of the heat pump does not run. Circulation pumps merely ensure that the thermal energy is transferred from the building to the ground via heat exchangers. Passive cooling is not possible with an air/water heat pump.
The Passivhaus Institut is an independent research institution founded in 1996. They test and certify buildings and components which are intended for converting a house into a passive house.
PID control is a control method that regulates temperature with a high degree of precision. It takes into account both the current deviation from the desired setpoint and the temperature trend in order to optimally adjust the system’s output.
Through continuous adjustment, PID control ensures a stable room temperature, enhances comfort and supports the energy-efficient operation of heating, air-conditioning and ventilation systems.
The Plug & Heat principle describes a really straightforward installation process that is particularly associated with air-water heat pumps: Simply put them in place, connect them, and get heating straight away.
The PLUS X AWARD is the largest innovation prize in the world for technology, sports, and lifestyle. It recognises brands for the quality and innovative edge of their products. That is why we are very proud of the fact that our product series of KERMI therm-x2 steel panel radiators won the PLUS X AWARD for its excellent properties. These include:
- therm-x2 Profil
- therm-x2 Plan
- therm-x2 Line
- Verteo
The Power-to-Heat function of heat pumps allows the use of excess photovoltaic electricity, for example. Power-to-Heat means the conversion of electricity into heat.
Pressure loss describes the resistance that the heating water must overcome as it flows through pipelines, fittings and radiators. The higher the pressure loss, the more energy the circulation pump must generate to circulate the heating water through the system.
An optimally balanced pressure loss contributes to the efficient and consistent operation of the heating system. Modern radiators and suitable valve technology help to support hydraulic balancing and reduce the system’s energy consumption.
Define the protection zones that specify the conditions under which radiators may be installed in rooms with high humidity – for example, in bathrooms or spa areas. Both the applicable electrical safety regulations and anti-corrosion protection play an important role in this regard.
Depending on the installation location, different requirements apply to materials, surface protection and, in the case of electric radiators, the protection type and the permitted installation area. Compliance with these protection zones ensures safety, durability and standard-compliant operation of the radiator, even in demanding environments.
A modern refrigerant with a lower GWP (Global Warming Potential) than older versions.
Radiators can emit convection or radiant heat. Convection heat rises in the room, heating the air and moving around within it. In contrast to that, radiant heat does not heat the air directly but heats the objects in the room and the walls. As a result, almost no dust is stirred up and the emitted heat creates a really cosy feeling.
The purpose of a radiation shield is to reduce heat radiation to the facade. The material plays only a minor role here. The important thing is to create an additional air shaft between the radiator and facade, and to allow the heat from the radiator to enter the room unimpeded. You will also find fixings for the radiation shield online in our KERMI spare parts shop.
You can find this information in the technical documentation for the relevant product in the downloads section of this website.
Steel panel radiators can be divided onto different types. The various types are: 10, 11, 12, 20, 22, 30, and 33. The designation depends on the number of heating plates and convectors installed and thus also on the depth. The first digit indicates the number of heating plates and the second the number of convectors. This means, the larger the number, the deeper the radiator.
RAL is a German institute for quality marks and labelling. It awards what are known as “RAL quality marks” to products and services of particularly high quality in various categories. However, RAL is best known for its RAL colour system, a colour identification system developed by the RAL Institute. KERMI also has a wide range of radiator colours available, which includes almost all RAL Classic colours. You will find more information on this in our KERMI colour concept.
The “Red Dot“ award is globally recognised as a seal of quality for good design. As the field of design is so diverse, the award is divided into three disciplines to enable a proper assessment: the Red Dot Award: Product Design, Red Dot Award: Brands & Communication Design, and Red Dot Award: Design Concept. Each of this competitions is held once a year. The Red Dot jury evaluates the submitted products, brands, and communication projects, as well as design concepts and prototypes.
The Red Dot Award: Product Design, whose origins date back to 1955, identifies the best products of each year. Manufacturers and designers from all over the world can enter their designs for the competition in around 50 categories. In keeping with its motto of “In search of good design and innovation“, the Red Dot Jury evaluates all the entries and only awards the Red Dot to products which truly demonstrate good design quality. (Source: www.red-dot.org)
The refrigerant is the working medium in the refrigeration cycle of a heat pump or air-conditioning system. It absorbs heat, transports it within the system and releases it elsewhere. It is this process that enables efficient heating or cooling.
Different refrigerants are used depending on the application. Modern refrigerants such as R290 (propane) are characterised by high energy efficiency and – depending on the type – a low global warming potential (GWP).
The refrigeration certificate is a certificate of competence that authorises qualified personnel to carry out work on refrigeration, air-conditioning and heat pump systems using fluorinated refrigerants.
It confirms the necessary knowledge for the safe handling of refrigerants, for example during installation, maintenance, repair or leak tests.
The refrigeration cycle is at the heart of a heat pump or air-conditioning system. It consists of four key components: the evaporator, the compressor, the condenser and an expansion valve, which reduces the pressure of the refrigerant before it enters the evaporator.
In the closed circuit, the refrigerant absorbs heat, transports it and releases it elsewhere. Depending on the operating mode, this allows heat to be used for heating or cooling, enabling the system to operate energy-efficiently.
Conversion, renovation, and modernisation projects are another area where KERMI offers a whole host of different options. Our replacement radiators are available in designer and steel panel versions and in a range of different heights, lengths, and depths. Suitable hub distances of 500 and 900 mm mean that old DIN radiators can be replaced quickly, easily, and cleanly with new radiators that fit perfectly.
Our replacement radiators are currently available for the following models:
Requirement classes specify the loads that a radiator fixing must be able to safely withstand in a particular area. They serve to ensure the structural and operational safety & security of radiators in accordance with the range of applications for which they are intended.
In areas with higher requirements – for example, in schools, nurseries, hospitals or public buildings – radiator fixings must withstand particularly high mechanical loads. The relevant requirement class defines the load-bearing capacity that the fixing must meet in order to ensure safe and consistently reliable operation. The selection of the appropriate fixing should therefore always be tailored to the intended range of applications.
Restoring forces are the forces which act on a pipe in the underfloor heating to return it to its original shape. Low restoring forces and high flexibility are advantageous for underfloor heating systems.
The return temperature specifies the temperature of the water after it has passed through the heating circuit.
A room temperature sensor is a device that measures the current room temperature and transmits this information to the control system of a heating, air-conditioning or ventilation system.
Based on the measured temperature, the system can adjust its output to meet demand, thereby ensuring a constant room temperature, a high level of comfort and efficient operation.
The SEER (Seasonal Energy Efficiency Ratio) is a measure of the seasonal energy efficiency of air-conditioning systems during cooling operation. It describes the ratio of the cooling output delivered over an entire cooling season to the electrical energy required to achieve this.
A high SEER value indicates that the air-conditioning system operates particularly efficiently and helps to reduce both energy consumption and operating costs. Compared with the EER value alone, the SEER takes into account varying operating conditions throughout the entire cooling season, thereby enabling a more realistic assessment of energy efficiency.
“Safety Extra Low Voltage” (= SELV): a low electrical voltage which ensures a high level of connection safety, as it offers special protection against electric shocks.
KERMI revolutionised heating with serial flow and its x2 technology. First of all, the front panel of the radiator heats up to deliver heat quickly and provide maximum comfort. In partial load mode, this is usually sufficient to meet the heat demand. The rear panel acts as a radiation shield. As the heat demand increases, the downstream panel is also heated up and then ensures max. heat output from the radiator.
Silent Mode is an operating mode for air conditioning systems in which the fan and compressor output are reduced in order to minimise the system’s noise level.
Thanks to its particularly quiet operation, this mode is particularly suitable for sensitive areas such as bedrooms and living rooms. At the same time, it helps to maintain a pleasant indoor climate with a high level of comfort whilst keeping noise levels low.
Adjustable air deflectors in the indoor unit of an air-conditioning system for controlling the airflow.
The Smart Grid Ready label is awarded to heat pump series that have control technology which allows the heat pump to be connected to an intelligent power grid via defined interfaces. All KERMI heat pumps have been awarded the SG Ready certificate.
The sound pressure level specifies the strength of a sound event which is received. This value is always tied to the distance or range, as well as the spatial environment.
The sound pressure level describes the perceived volume of a device and is expressed in decibels (dB(A)). It indicates how loud a sound is perceived at a specific measurement point, taking into account the sensitivity of the human ear.
In air-conditioning, ventilation and heating systems, a low sound pressure level is a key factor in ensuring comfortable operation – particularly in living and sleeping areas. Modern appliances are designed to combine efficient performance with the quietest possible operation.
Should you need any spare parts or accessories for your radiator or residential ventilation system, our products can be purchased from your nearest qualified specialist installer. To find a specialist partner near you, please refer to our Specialist partner overview.
In addition, you will also find a selection of spare parts and accessories in our KERMI spare parts shop , which you can order online from the comfort of your own home.
Air conditioning with separate indoor and outdoor units.
Start-up current has the name brief spike in power demand that occurs when the compressor of a split air-conditioning system or heat pump starts up. Once the compressor has reached its operating speed, power consumption returns to normal operating levels.
Modern units with inverter technology limit the start-up current by ramping up the compressor continuously. This reduces the load on the mains supply, increases energy efficiency and protects the system’s components.
The summer bypass function cuts out the heat exchanger phase. This means, for example, that the cool night air can be conveyed into the house at the height of summer without it being heated up by the extract air.
The supply air is the temperature-controlled (treated) and filtered air that flows into the living space.
Thermal resistance is an important factor for assessing the insulating properties of a building component. The higher this value, the better the insulating properties of the building component concerned.
A control unit for setting the desired room temperature.
To make it easy to lay the x-net underfloor heating, there is a special unrolling unit (centre-pull feeding). This ensures that the pipes can be unrolled quickly without twisting and can then be laid. This allows work on the construction site to be carried out quickly and without any complications.
The two-pipe system comprises separate flow and return pipes. This means that all radiators can be heated evenly – also with the help of hydraulic balancing.
A valve radiator is a steel panel radiator with an integrated thermostatic valve. This allows a thermostatic sensor head to be installed directly, thereby enabling precise control of the room temperature. The connection is usually made from below, allowing pipelines to be discreetly integrated.
Valve radiators are ideal for new builds and refurbishments. They combine a clean, unobtrusive appearance with high energy efficiency and can be used with a wide variety of heat sources.
Valves can be used to control the flow rate of the radiator in accordance with the measured temperature in order to control the set temperature or keep it constant. The further the valve tappet is pressed into the valve, the lower the flow rate of heating water, and vice versa.
What should you do if the valve stops working?
When radiators are not used for a long time, the valve tappet can get stuck due to deposits. It often helps to remove the thermostatic sensor head and to move the tappet several times. In many cases, the problems can be avoided by turning the radiator thermostats to position 3 in empty homes. The valve is then kept continuously in motion and no deposits can form. In some cases (heavy incrustation), the only alternative is to replace the valve insert. Once again, care should be taken to avoid periods of valve inactivity. Note: Valves should only be replaced by a specialist partner!
What should you do if the valve is tapping?
If the valve is making a “tapping” noise, it suggests that the feed and return on the radiator have been mixed up. You can check this by allowing the radiator to cool down. If everything has been connected correctly, the pipe pointing to the middle should get warm afterwards when the valve is left open. If this is not the case, then a reverse manifold needs to be installed. So if your radiator is not heating up properly and you can hear a tapping noise, please contact your local specialist installer.
Where can I find information on valve inserts?
You can find out everything you need to know about KERMI preset valves in the pocket-sized practical valve guide (insert link here).
How do I replace valve inserts?
Valve inserts should always be replaced by a specialist partner to ensure that your radiator continues to work properly. Please contact your qualified specialist installer about this. Relevant spare valves are also available from them.
The volume flow describes the volume of air that flows through a ventilation unit per unit of time. It is usually expressed in cubic metres per hour (m³/h) and is an important indicator of the performance of a residential ventilation system.
A correctly regulated volume flow ensures that sufficient fresh air enters the rooms and that stale air is reliably extracted. In this way, it contributes to high air quality, a comfortable indoor climate and energy-efficient operation of the ventilation system.
A Wi-Fi module allows you to conveniently control an air-conditioning unit or other room climate control system via a smartphone, tablet or network.
Using a suitable app, functions such as temperature settings, operating mode or timers can be conveniently adjusted remotely. The Wi-Fi module thus offers added convenience and supports the efficient, needs-based use of the system.
The German Sanitation, Heating and Air Conditioning Association (Zentralverband Sanitär Heizung Klima, ZVSHK) is a professional organisation, trade association, and body representing the interests of the plumbing, heating, and air conditioning (SHK) industry in Germany. (Source: ZVSHK)