Specialist terminology explained in a way that is simple and easy to understand! Are you planning a new-build, modernisation, or refurbishment? When it comes to heat pumps, radiators, underfloor heating, residential ventilation, and smart homes, you will be confronted with many technical terms. Our alphabetically sorted reference book is designed to help you better understand the terms from the fields of intelligent heating and ventilation.
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 as a comparison to other ventilation units in contrast to the sound pressure level
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 from the building using the heat pump. For this purpose, the compressor of the heat pump is operating (active).
Design radiators with additional electric operation are connected to the central heating network, however can be operated electrically independently of it. This is particularly suitable in transitional periods and for short-term heat demand. More information on electric operation of design and bathroom radiators.
The air vent plug seals the heating system to the outside. It can easily be removed to bleed the radiator.
Radiators with all-electric operation are independent of the central heating network, because here a socket is sufficient as an energy connection for the installation. Especially in old buildings, they are a time and cost-saving solution for modernisation. But even in energy-autonomous new-builds with solar panel systems, the self-produced electricity can be used with the help of an electric radiator. More information on our electric radiators.
Like the COP, the annual COP value is an important criterion for the efficiency of heat pumps. In comparison to the COP, this does not represent a particular operating point, but is a ratio between the amount of heat generated for heating and domestic water heating over the whole year and the electrical energy required. The annual COP depends on many factors and apart from many parameters of the heating system, also takes the location of the heat pump into consideration.
If the funding is approved by BAFA for the replacement of the heating system, the approval period starts. During these 12 months, the funded measures are implemented. If the measures should be delayed, there is the possibility of extending the deadline.
On the one hand, the Federal Office of Economics and Export Control exercises an administrative role in the areas of foreign trade, energy business promotion, and auditor supervision. It also promotes energy-efficient technologies and energy-saving measures.
A blanking plug seals the heating system to the outside 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 buffer charging pump moves the heat generated by the heat pump to the buffer or domestic water tank.
A distinction is made between a
Dust formation inside the radiators is a natural process, which is associated with the circulation of the warmed air and cannot be technically prevented. 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 comfortably online from our Kermi spare parts shop. You will find a specialist partner near you in our specialist partner overview.
You can also clean your radiator with household cleaning agents. Suitable cleaning agents for paint surfaces are not abrasive and not strongly alkaline or acidic (chemically aggressive).
To be able to clean the radiator properly, you first of all 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. From length 1000 for Plan radiators or length 1400, the Profil radiator retaining bar also needs to be removed from the upper cover. After that, pull the side panel off the radiator at a slight angle and detach it from the fixing hooks after lifting the top cover. Then separate the top cover from the second side cover by lifting it at one side and sliding it. After cleaning, installation of the top cover is carried out in the 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 would like to reduce its CO2 emissions by at least 55 percent.
CO2 emissions refer to greenhouse gases produced by the combustion of, for example, coal, diesel, petrol, natural or liquid gas, and wood. The CO2 created during the combustion process, accumulates in the atmosphere and is largely responsible for the greenhouse effect and global warming.
With a standardised 50 mm centre connection, Kermi has made a standard possible that provides you with complete planning and decision freedom right until the end. With nearly all valve versions, the connection is completely hidden underneath a panel. The classic version with the left and right side connection is also available for many models. With the centre connection, the connection of the feed and return pipe is not important as there is a block (partition disc) between the two connections. You will find further information on the Kermi connection types in the technical documentation for the respective product.
The coefficient of performance (COP) refers to a defined operating point (e.g. A2/W35 – air temperature 2 °C, flow temperature 35 °C) of the heat pump. The COP represents a snapshot and defines the heat output in relation to the electrical power consumed.
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 power coating. It protects the radiator from damage caused by moisture and can also be applied under coloured paint finishes.
Radiator covers protect the inside of the radiator from dirt on the one hand, and on the other hand, 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.
Panels 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 panels for radiator connections and fixings in our Kermi spare parts shop.
Are you looking for a specialist partner near you to be able to see our products in the flesh, get some advice, or place an order? You will find a specialist partner near you in 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 device through a pipe system.
An EC motor (electronically commutated motor) is a brushless DC motor designed as a three-phase asynchronous motor which is excited by permanent magnets. The rotary field is realised 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 advantage is the extremely high efficiency and the infinitely adjustable speed control using commutation electronics.
The efficiency describes the ratio of useful energy to supplied energy. The higher the efficiency, the more efficiently the unit is working.
On the basis of the Energy Saving Act, the Energy Saving Ordinance (EnEV) sets standard requirements for privately and commercially used new-builds, for example 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.
Leading companies around the world from the building industry have grouped together to form the EnOcean alliance. It stands for energy harvesting wireless switches, sensors, and receivers for building automation, to make buildings more energy-efficient, flexible, and cost-effective.
In contrast to normal heat exchangers, enthalpy heat exchangers can also recover moisture. In the winter, this provides the advantage that the natural drying out process that occurs in living space is slowed down. This can contribute towards raising the moisture level in living space to a value which is more comfortable. Of course, it is important, particularly in the cold times of year, to adjust the air volumes to the actual demand and to prevent overheating the rooms to more than 23 °C to keep the humidity at >35 %.
When installing a new heat pump or replacing old devices as part of the BAFA funding programme, some work needs to be carried out in advance. Consultations, planning or measures to ensure energy efficiency are referred to as environmental measures and are just as eligible for funding as the heat source itself. This includes, among other things, heating and plant rooms, dismantling work, earth drilling, and disposal of old oil and gas tanks and much more.
From 2026 onwards, no pure oil heating systems may be installed in new-builds. Only the installation of regenerative systems or the use of hybrid systems that use renewable energies in addition to oil to generate heat is now permitted. The German government's new climate package comprehensively updated and expanded the market incentive programme. This subsidy is also referred to as an exchange bonus.
Exhaust air is the name given to the used air which has already passed through the ventilation unit and the heat exchanger. This means it is the used air which has already dissipated its heat and is being discharged to the outside.
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.
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. Fine dust and pollen, but also spores, viruses, and bacteria from the outside cannot get into the building. In addition to that, outside air filters protect installed components from getting dirty.
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 and prevent the unit from becoming dirty. This ensures clean operation of the heat exchanger and the efficiency of the heat recovery is maintained.
You can order original Kermi filters for your controlled residential ventilation quite easily and comfortably from the Kermi spart parts shop.
The flow temperature refers to the temperature that the water needs to heated to before it flows into a heating circuit, for example a radiator or underfloor heating.
To make it easy to lay the x-net underfloor heating, there is a special dispensing unit (centre-pull feeding), which ensures that the pipes are unrolled quickly, without twisting and can then be laid. This makes quick, uncomplicated work possible on the construction site.
With brine/water heat pumps, the thermal energy from the environment is collected 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 of up to 100 m. For that reason, they require a permit. The advantage over geothermal collectors is the significantly smaller space requirements and higher source temperature over the year, which allows greater efficiency of the heat pump.
Most Kermi design 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 differ between the manufacturers, please contact the respective manufacturer or the recorder for details. Yo will find further information in our technical documentation for the respective product.
What to 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 so 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 act. There are many possible causes for a heating system not heating evenly and they range from air in the heating system to faulty pressure conditions in the heating system.
A remedy is provided by using a Kermi radiator with x2-technology where the front panel is flowed through first. The front panel becomes uniformly warm and the rear panel serves as a shield against the cold outer wall during the partial load mode (90 % of the heating period).
More information on our therm-x2 radiators. You will find a specialist partner near you in our overview.
The heat output of a radiator depends on various factors, such as the flow temperature, the size, as well as the design. If, for example, the flow temperature is very low, the radiator selected should be larger, but there are also radiator versions that deliver considerably more output for the same size. The different versions can be distinguished as type 10, 11, 12, 20, 21, 22, and 33. The larger the number, the deeper the radiator. The first number respectively indicates the number of heating plates, the second, the number of convectors.
You can find the precise heat output of our radiators in the technical information of the relevant product in ourDownload area. When determining the heat output, please ensure that the temperature pairing is selected 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 common today.
Please contact your specialist installer for a precise calculation.
The heat recovery describes making energy reusable. Using the ventilation system as an example, the heat 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 respectively, based on the amount of heat made available (efficiency).
The heating load of a building specified how much thermal energy needs to be introduced into the building to achieve idea thermal comfort, despite losses – e.g. through doors and windows.
Different heat generation technologies are combined in a hybrid system. Frequently the classic energy sources such as oil or gas are linked to renewable energy sources allowing the strengths of two different heating systems to be combined.
To ensure that the heating system works without any problems, the flow rate of the hot water needs to be adjusted to the heat demand of every individual radiator. Kermi radiators with valve are preset in the factory according to the standard heat output of the radiator. This saves energy costs and ensures optimal heating comfort. More information on the topic Valve technology & hydraulic balancing.
The globally operating jury of the International Forum Design in Hanover honours products in daily use that stand out in 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 around 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 design and bathroom radiators have already been awarded the prestigious iF Design Award. They include:
An infrared radiator is an electrically operated radiator. It provides a high proportion of efficient, cosy, radiant heat. This heat 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.
Kermi Clips are used to fix the side covers of the radiator. These are supplied as standard with each radiator with covers that can be installed on the sides. If you should require a replacement despite this, you can simply 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 a range of funding programmes, they support developers among other things when buying residential property and with energy-efficient construction while saving resources. 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), at a pressure difference of 1 bar and a water temperature of 5–30 °C.
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 funding programme creates incentives to generate heat from technology based on renewable energies. This includes for example heat pumps, replacing old oil heating systems, or hybrid systems.
With a wirelessnetwork, the reception is distributed through the apartment with an individual unit, the router. A Mesh network in contrast is set up in the whole living space using various access points.
A modulating (performance controlling) heat pump can adapt its heat output to the heating requirements of a building. This allows the heat pump to work more quietly and more efficiently and optimally adapt to different outside temperatures.
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.
As an end customer, you can get our products from your qualified specialist installer. They will be glad to make you an offer.
You will find a specialist partner near you in our overview.
In addition to that, you will find spare parts and accessories for your radiator or your residential ventilation in our Kermi spare parts shop and can easily order these online from home.
The air that flows in from outside.
You can use our touch-up pencil or our spray can to repair minor paint damage to the radiator. Both are available in the colour RAL 9016 (white). You can buy these products from your qualified specialist installer, from specialist wholesalers, or comfortably online from our Kermi spare parts shop.
A building can be cooled with the passive cooling function. During passive cooling, the compressor of the heat pump is not operating. Only circulation pumps ensure that the heat 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 to convert a house into a passive house.
The Plug & Heat principle describes the uncomplicated installation – in particular of air-water heat pumps: They simply need to be set up, connected, and then you can already start heating.
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:
The Power-to-Heat function of heat pumps allows the use of e.g. excess photovoltaic electricity. Power-to-Heat means converting electricity into heat.
Radiators can emit convection or radiant heat. Convection heat rises in the room and heats the air and moves around in 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 heat emitted is perceived as being particularly pleasant.
A radiation shield should reduce heat radiation to the facade. Material plays a minor role. It is important that between the radiator and facade an additional air shaft is created and the radiator warmth can get into the room without being impeded. You will also find fixings for radiation shield online in our Kermi spare parts shop.
Steel panel radiators can be divided onto different types. There is type 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 construction 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 so-called “RAL quality marks” to products and services of particularly high quality in various categories. However, the term RAL is best known for its RAL colour system, a colour identification system of 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. In order to be able to professionally evaluate the diversity in the field of design, the award is divided into three disciplines: the Red Dot Award: Product Design, Red Dot Award: Brands & Communication Design, and Red Dot Award: Design Concept. Every competition is organised 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, which has existed in its origins since 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. True to the motto “In search of good design and innovation“, the Red Dot Jury evaluates all the entries and only awards the Red Dot to products which are notable due to their good design quality. (Source: www.red-dot.org)
That is why we are very proud that our Elveo design and bathroom radiator was awarded the Red Dot Design Award 2019.
Conversion, renovation, modernisation – Kermi also offers many different options here. Our replacement radiators and design radiators are available in a range of different heights, lengths, and depths. With suitable hub distances of 500 and 900 mm, 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:
You will find further information under the heading Renovation solutions on our website.
Reset forces are the forces which work on a pipe in the underfloor heating to return it to its original shape. Low reset forces and high flexibility are advantageous for underfloor heating systems.
The return temperature specified the temperature of the water after passing through the heating circuit.
“Safety Extra Low Voltage” (=SELV): a low electrical voltage which ensures high connection security, as it offers special protection from an electric shock.
Kermi revolutionised heating with serial flow and its x2 technology. First of all, the front panel of the radiator heats up and quickly provides heat and 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.
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 specified the strength of a noise event which is received. This value is always tied to the distance or range, as well as the spatial environment.
If you should need a spare part or accessories for your radiator, you can get our products from your qualified specialist installer. You will find a specialist partner near you in our Specialist partner overview.
In addition to that, you will find selected spare parts and accessories in our Kermi spare parts shop and can easily order these online from home.
The summer bypass bypasses the heat exchanger. This means that for example at the height of summer, the cool night air can be conveyed into the house 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 in the efficiency of underfloor heating. It is calculated from the thickness of the floor covering on the underfloor heating and the heat conductivity. The higher the thermal resistance, the less efficiently the underfloor heating can work, as the heat is emitted before the actual location where it is needed.
Thermostatic sensor heads to do not always need to look boring. At Kermi you will find thermostatic sensor heads of different designs, in chrome, stainless steel look, and chrome white – matched to your radiator.
As an end customer, you can get our products from a qualified specialist partner near you. You will also find our design thermostatic sensor heads in our Kermi spare parts shop and can easily order these online from home.
For maximum comfort, we offer matching towel rails, hooks, and hangers for almost all our design, bathroom, and steel panel radiators in white, chrome, painted aluminium, brushed stainless steel, painted stainless steel, or anodised silver.
As an end customer, you can get our products from a qualified specialist partner near you. You will also find our towel rails, hooks, and hangers in our Kermi spare parts shop and can easily order these online from home.
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.
Valves can be used to control the flow rate of the radiator, depending on 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 hot water and vice versa.
What to do if the valve no longer works?
For radiators which have not been used for a long time, the valve tappet may have become 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 apartments. The valve is then kept continuously in motion and no deposits can be formed. In some cases (heavy incrustation) the only alternative that remains is to replace the valve insert. Then as well it is important to ensure that times where the valve is at a standstill are avoided. Note: Valves should only be replaced by a specialist installer!
What to do if the valve is tapping?
The valve “tapping” suggests that the feed and return valve on the radiator have been mixed up. You can check this by allowing the radiator to cool down. If connected correctly, then afterwards when the valve is open, the pipe pointing to the middle should get warm. If this in 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 specialist installer near you.
Where can I find information on valve inserts?
You can find out everything you need to know about Kermi valves preset in the factory in the practical valve guidebook in pocket format (insert link here).
How do I replace valve inserts?
Valve inserts should always be replaced by a specialist installer to ensure that your radiator continues to work properly. Please contact your qualified specialist installer about this. You can also get relevant spare valves there.
There are special attachments for window boxes for on steel panel radiators, convectors, and Kermi DECOR. You will find the attachments in the technical documents on the respective product. We do not supply window boxes or similar covers.
You will also find fixings for window sill supports online in our Kermi spare parts shop.
With the central Kermi x-center base station, you can conveniently control and easily manage all components of the “Kermi system x-optimised” via PC or tablet, e.g. electric heating rod on the bathroom radiator, heat pump, ventilation, underfloor heating, or radiators, at home – or while out and about too. Other products by different suppliers can also be integrated via the universal EnOcean interface, e.g. switch actuator, window contact, blind, detector, sensor, and switch.
Find out quite easily which products are compatible with the x-center base here.
The Central Association for Sanitation, Heating and Air Conditioning (ZVSHK) is a professional association, trade association, and representation of interests of the sanitation, heating, and air conditioning trade in Germany. (Source: ZVSHK)