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Having radiators replaced: professional measures

Picture: © RossHelen /

There is no denying that damaged, outdated or inefficient radiators must be replaced. But how exactly does the preparation and replacement by a heating system installer work? What is important when selecting suitable new radiators? And what are the costs? Furthermore, the question of whether radiators really need to be replaced cannot always be answered definitively. Radiators getting on in years often still work. However, good reasons to have them replaced – and answers to many other questions – can be found in this guide.

Reasons and causes for having radiators replaced

Initially, there is usually the question: do I have to have my radiators replaced? Apart from leaks, rusted-through spots or other obvious defects, this question can always be answered with yes if your old radiators...

  • remain in operation without having been checked after a heating system modernisation or energy saving refurbishment. They usually no longer match the heating demand of the new boiler (modernised building) and have differently sized heating surfaces as well as a different water demand.
  • no longer match the newly installed heat generator, such as a heat pump or solar thermal system, which operate with lower flow temperatures.
  • create an unnecessarily poor room climate and possibly cause cold floors.
  • are installed in locations that are no longer appropriate after energy saving modernisation/insulation, for example in cold window recesses with thermal bridges where heat is lost to the outside of the building.
  • have deposits of limescale and debris inside the radiators that prevent efficient and cost effective operation of the modernised heating system.

When is it sufficient to repaint old radiators?

If it has been shown that radiators will remain functional for some time to come, there are alternatives to replacement. In individual cases, it may be an option to repaint or recoat the radiators. There are good reasons to keep the old radiators in operation in the following cases:

  • when underfloor, wall or ceiling heating is installed as part of the heating system modernisation. The old radiators then only support the area heating system when required.
  • when the radiators have sufficiently large surfaces to heat the room with the lowest possible temperatures, are in good working order and equipped with a suitable control unit that matches the new heating system.

The most important facts about costs, subsidies and savings opportunities

Replacing a radiator is of course primarily associated with the purchase cost for the replacement radiators. If carried out professionally, there are also costs for the installation as well as the removal and disposal of old radiators. The price depends on a variety of local conditions. These include radiator type, number of heating surfaces required and rooms to be heated, as well as the complexity of the work. Depending on the agreed scope of services, the heating system installer will offer further services, such as hydronic balancing and regular maintenance. All the work described varies from case to case, so that it is impossible to quote a flat price for the replacement of radiators. Request a non-binding expert consultation via the Viessmann trade partner search to be put in contact with a heating system installer who will prepare a suitable quote subject to your personal requirements.

Reducing energy consumption and heating costs by replacing radiators

In order to save costs by replacing radiators, new radiators must be accurately matched to the room requirements in terms of size and performance. This involves calculating your personal energy and heat demand and depends, among other things, on the energy conditions inside the house.

The required calculations should be carried out by an expert who is familiar with the individual parameters. As an intermediate result, they determine the heat load required. The final result is the heating output required of the radiators in kilowatt hours. 

Grants and subsidies for the installation of new radiators

You can have these services subsidised by means of government funding as part of an energy consultation. In Germany, a grant of up to 50 percent of eligible costs is available for specialised energy planning. In addition, trades services may be tax-deductible. In this case, the subsidy amounts to 20 percent of a maximum of 6000 euros per year.

However, the installation of low temperature radiators can also be subsidised as heating system optimisation with a grant of up to 20 percent via the Federal Funding for Energy-Efficient Buildings (BEG). Likewise, such radiators are also considered to be eligible peripheral measures when modernising a heating system.

Picture: © Roman Samborskyi /

Selecting the right radiator for a cosy home

In addition to appearance and type, the way heat is emitted is particularly important for the right radiator. This can take the form of radiation or convection. Cool indoor air is heated by convection. Radiant heat, on the other hand, is felt when it meets solid bodies or surfaces. Humans naturally experience radiant heat as more pleasant. A high proportion of radiation in the emitted heat therefore generally leads to a more comfortable home. But convection heat also has its advantages. For example, air heats up faster than a solid surface, so that the temperature can be regulated up and down more quickly.

Most modern radiators emit both radiant heat and convection heat in varying proportions. Talk to your heating system installer about the pros and cons to find the optimum mix for your needs.

Which and how many radiators for which room?

The actual radiator output required depends not only on the type of radiator but also on whether it will be installed e.g. in the bathroom or the living room. An experienced contractor will take these and other factors into account when making a heat load calculation. This includes the size and orientation of the respective room along with the energy status of the building and the output range of the radiator that is being considered for the room. The result of such a calculation is a determination of the output in watts. It is not possible to assign blanket values to specific rooms or room sizes due to the multitude of influences on site. To get an advance overview, there are rules of thumb. However, to ensure reliable planning of your radiators, this should be done together with a professional.

Types of radiators at a glance

Once you have decided to have your radiators replaced, there is a wide range of radiators to choose from. Use the following links for an overview of the Viessmann Vitoset radiator range, or go directly to the relevant product line:

Frequently asked questions about radiator replacement

The fundamental issues regarding radiator replacement will be clarified by the contractor. In addition, there may be some questions that you would like to have answered before you place your order for a replacement. If you have already decided to replace your radiators, here are a number of specific items that arise frequently.

The time required for professional removal and installation can vary considerably. It depends on a number of things including the position and number of connections, valves and other fittings. Similarly, it matters which type of radiator you switch to and how complex the new technology is compared to the old one. As a rule, it is a comparatively quick measure. If in doubt, ask your heating system installer how long the replacement will take and find out how much time needs to be planned for the work.

If you task a heating system installer with replacing your radiators, they will of course also dispose of the old radiators. This is strongly recommended. Not only do old radiators weigh up to 20  kg, they are also classified as scrap metal and must be disposed of properly. This involves cleaning and draining them completely. The reusable metals can then be separated from each other and recycled. Otherwise, private disposal would incur the cost of transport and possibly fees at the local waste collection point.

If you have decided to install underfloor heating instead of new radiators, you can look forward to many benefits. It should be noted, however, that such an area heating system can only be considered after the building has undergone an energy efficient modernisation. Otherwise, the measure is not profitable due to the poor cost-benefit ratio.

A towel rail radiator naturally has different dimensions from a "conventional" bathroom radiator, which is of course no problem for a contractor. The installation of an additional electric heating cartridge will also prepare you for cooler summer days when you might like your bathroom to be a few degrees warmer but don't want to switch on the entire heating system. There is also the option of having an electric bathroom radiator installed. In this case, factor the electricity costs into your planning.

According to German tenancy law, tenants may expect the technical standard that was relevant at the time of the construction of the building. According to the Federal Supreme Court, this also explicitly applies to the heating system including radiators. If this is in the contractual condition, i.e. as viewed, the landlord does not have to take action. Accordingly, an older heating system does not justify claims for modernisation or even rent reduction. Not even if the system operates inefficiently or if the rest of the building has previously been modernised.

However, the obligation to modernise on the part of the landlord includes the aforementioned obligation to replace after 30  years in accordance with the EnEV. Irrespective of a complete replacement, which is also the landlord's financial responsibility, the landlord is responsible for the maintenance and servicing of the heating system including radiators. One of the criteria here is the heating output. This must allow a minimum temperature of 20  degrees Celsius in the living spaces.


  • make noises?
  • get warm only at the top or unevenly?
  • don't get warm at all?
  • run with high heating costs?

In these cases, there are other measures to take initially that can lead to success. This includes bleeding the heating system and hydronic balancing. If the radiators do not get warm at all, the system pressure may be too low. In this case, it is necessary to have heating water topped up. Furthermore, valves, pipes and other critical locations should be checked regularly for blockages and contamination. In the event of excessively high heating costs, it may be worthwhile to replace the thermostats with programmable or intelligent thermostats.

If radiators and boilers were installed together, the answer depends on the age of the entire system. There are various details circulating on the internet about the age at which you should start thinking about a replacement. Approximately 15  years of operation is considered as a guideline. Many heating systems in Germany are older than this. According to the German Energy Saving Ordinance (EnEV), constant temperature boilers older than 30  years must be replaced. From a technical point of view, it is advisable to replace the radiators by this date at the latest.

As already described, modernising a heating system after such a long time alters the energy conditions considerably and old radiators will no longer be suitable for the new system. While operation may still be technically possible, it is often no longer advisable from an economic and ecological point of view.

It is essentially impossible to make a general statement about the service life of radiators. Values range from 40  years of operation to 20  years. Factors such as the contamination of pipework as a result of the very long operating time also have an influence, which is why the final decision as to whether you can continue to keep your old radiators in operation is up to the contractor.

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