Last updated: August 8, 2021

Welcome to our large heat meter test 2021. Here we present all the heat meters we have tested in detail. We have compiled detailed background information and added a summary of customer reviews on the internet.

We would like to make your purchase decision easier and help you find the best heat meter for you.

You will also find answers to frequently asked questions in our guide. If available, we also offer interesting test videos. Furthermore, you will also find some important information on this page that you should definitely consider if you want to buy a heat meter.


  • Heat meters measure the consumption of heat within a specified period of time (usually 1 year).
  • In order for the heat meter to provide the most accurate data possible, professional installation is necessary. For this purpose, a specialist should definitely be commissioned, especially for initial installation.
  • The calibration period for each heat meter is 5 years. After this ridge has expired, an accurate calculation of the heat can no longer be guaranteed.

The Best Heat Meter: Our Choices

Guide: Questions you should ask yourself before buying a heat meter

How do heat meters work?

As the name suggests, the heat meter measures heat. To be more precise, the heat meter measures the consumption of heat or the transport of energy over a certain period of time.

Heat meters calculate the heat consumption within a certain period of time (Image source: / ri).

This is heat that is needed for heating rooms and/or heating water.

Consumption is calculated by multiplying the volume flow of the heating water and the heat capacity by the temperature difference between the flow and return temperatures. The result is given in kilowatt hours (kWh).

The formula on which the calculation is based is: Q = m x c x dt.

(heat quantity in kWh = volume flow of the heating water x heat capacity x temperature difference between flow and return)

Every heat meter consists of three elements: flow sensor, calculator and temperature probes. These temperature probes measure the temperature difference of the water in the flow and return. This difference can be used to calculate the heat consumption.

Heat meters that use ultrasonic waves for data measurement include the average flow velocity and the pipe cross-section in the calculation instead of the volume flow.

When are heat meters used?

Heat meters are used when precise billing of heat consumption is necessary. This is the case, for example, when:

  • one heat source supplies several units (district heating or rented houses),
  • if a distinction must be made between commercially and privately used units,
  • if the consumption of the supplied heat is to be calculated separately from the consumption of the hot water, and
  • in the case of solar systems, in order to calculate the efficiency of the system.

What does a professional installation of a heat meter look like?

To ensure that the heat meter can also record the heat consumption accurately, special attention must be paid to professional installation and should therefore definitely be carried out by a specialist.

Particular attention must be paid to the installation of the volume flow meter and the temperature sensors. In principle, measurements must not be taken behind bends or T-pieces, as these falsify the measured value. The size of the volume flow meter must be adapted to the flow rate.

To ensure that your heat meter can measure accurately, professional installation is absolutely necessary and hiring a specialist is more than advisable.

When installing the temperature sensors, it is important that they are placed in the same heating circuit and that their cables are installed without kinks. Furthermore, attention must be paid to the flow direction of the heating system, the compatibility between sensors and computer and the installation position.

What does a heat meter cost?

As with all devices, the price of heat meters depends on the size and features of the device.

The cost of a smaller device, for example for detached houses and apartment buildings, is between €100 and €200, with additional costs for installation.

What are the alternatives to heat meters?

Alternatives to heat meters are either evaporation tubes or digital models that are mounted directly on the radiator.

Compared to heat meters, they are a lot cheaper (and therefore more popular with many landlords), but their calculation is less accurate.

Alternative Advantages Disadvantages
Evaporation tubes Cheaper Need to be replaced annually, Inaccurate measurement
Digital models for the radiator Serve several years, Easy reading, Cheaper Inaccurate measurement

Therefore, heat meters are more popular today, as their accurate calculation of heat consumption can contribute to a good tenant-landlord relationship.

Decision: What types of heat meters are there and which is the right one for you?

When you decide to buy a heat meter, there are two alternatives you have to choose between:

  • Compact unit
  • Composite unit

The only difference between the two product types is their design. Both product types have advantages and disadvantages and it depends on the intended use which heat meter suits you better.

In the following paragraphs we would like to help you decide.

What are the characteristics of a compact device and what are the advantages and disadvantages?

Compact heat meters consist of a compact device, i.e. they combine the computer and the volume measuring part in their housing. The associated temperature probes are attached separately on the outside.

Combining these elements into one compact device not only makes it more manageable, but also less expensive. However, this compact heat meter is also calibrated as a whole. This means that the entire device must be replaced during calibration.

  • A compact device
  • inexpensive purchase
  • Must be replaced as a whole
  • Inflexible
  • Not suitable for high buildings

In the long run, this can lead to higher costs, even if the initial purchase of the unit is cheaper. Furthermore, due to its inflexibility, this unit can only be used in low buildings.

What are the characteristics of a composite unit and what are the advantages and disadvantages?

In compound units, the computer and volumetric meter are in separate housings, but they are connected together with the temperature probes to form a compound.

The clear advantage of these composite devices is that the individual elements are calibrated separately from each other and can also be replaced separately from each other.

On the one hand, this increases flexibility and also the areas of application, as they can be individually adapted for each measuring task. Therefore, they are also optimally suited for higher structures.

  • Flexibility
  • Individual adaptation to every measuring task
  • Specialist is needed more often
  • Increased maintenance work

However, the increased flexibility also entails various disadvantages. If the measurement is faulty, the entire device cannot simply be replaced, as is the case with compact heat meters. Rather, the source of the error should be determined and only the faulty element should be replaced.

However, this requires manual skill, or a specialist is always needed.

Purchase criteria: You can use these factors to compare and evaluate heat meters

In the following, we will show you which aspects you should pay attention to when buying your heat meter.

The criteria to consider when buying include:

  • Size
  • Radio module
  • Temperature probes
  • mechanical or ultrasonic measuring component
  • Single-beam vs. multi-beam design

In the following paragraphs, we will explain to you what is important in each of the criteria.


The selection of the size of the heat meter depends on the volume flow that is to be calculated. This is difficult for a layman to understand, as this value should be known.

Therefore, it is advisable to consult an expert, especially when buying for the first time.

Radio module

Radio modules are an additional feature of heat meters. With the help of the radio module, the measured values can also be read outside the flats, which is very advantageous for the annual heating bill.

Temperature sensors

As already mentioned, the temperature sensors are responsible for measuring the temperature difference between the flow and return of the heating water.

Digital output devices make it easier to read the data recorded by the heat meter (image source: / Skitterphoto).

These sensors are designed as platinum resistance thermometers. Therefore, it is always important to use high-quality platinum for an optimal measurement result.

Mechanical or ultrasonic measuring component

A distinction is made between the following measuring components

  • mechanical (rotating)
  • Ultrasonic (static)

A mechanical measuring component can be, for example, an impeller counter or a Woltman counter.

Measuring components that work according to the ultrasonic principle use the entrainment principle and calculate the transit time difference of the flow and return. The clear advantages of the ultrasonic principle are the increased measuring accuracy and the unrestricted installation options.

Single-jet vs. multi-jet design

Single-jet heat meters differ from multi-jet heat meters with regard to the measurability of volume flows.

While single-jet meters are preferably used as compact devices for very low volume flows, multi-jet meters are used in larger heating systems.

Facts worth knowing about heat meters

What is and how long is the calibration period for heat meters?

The calibration period for heat meters indicates when the device must be recalibrated. According to the current Measurement and Calibration Ordinance (MEssEV), this occurs every 5 years.

For consumer-friendly handling, the heat meter is marked with the date of the last calibration.

The calibration period for your heat meter is 5 years. It is essential to observe this period, as accurate calculation can no longer be guaranteed after it has expired.

In the case of compound devices, all parts are calibrated individually before they are calibrated again as a compound. Compact appliances, as already mentioned, are calibrated or replaced as a whole.

How are heating costs calculated correctly?

There are various methods for calculating heating costs. As a tenant, it is therefore always advisable to ask the landlord annually for the breakdown in order to get a better insight and overview of the actual consumption and to be able to initiate possible savings measures.

A common method of measuring heating costs is to calculate them on the basis of the average heating costs per square metre.

Heat meters not only calculate the consumption of heat from heaters, but also the consumption of hot water (Image source: / Imani).

The average cost per square metre in Germany in 2017 for natural gas was €11.30, for heating oil €10.70 and for district heating €12.80.

Since not only the energy source but also other, numerous individual factors play a role when calculating heating costs, it is advisable to also have your own heating costs calculated individually and to compare them.

What is the legal situation regarding heat meters?

The Heating Costs Ordinance stipulates that landlords must accurately calculate at least part of the tenants' energy consumption and are therefore obliged to install appropriate devices.

Either tested and calibrated heat meters or heat cost allocators can be used for this purpose.

Image source: / lemonbeat

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