Ultrasonic Heat Meters (Threaded, DN20–DN40)

Ultrasonic heat meters are modern heat meters that measure the heat energy consumed in central heating and cooling systems with high accuracy; as they contain no moving mechanical parts, they are long-lasting and reliable. The threaded DN15, DN20, DN25, DN32 and DN40 models in this category are compatible with manifold-based installations. You can filter Novus Digitermo, Minol Zenner, Calmet, CEM, İntegral, Danfoss and Honeywell models by brand and communication module (M-Bus, RF/wM-Bus) and compare prices.

How Does an Ultrasonic Heat Meter Work?

An ultrasonic heat meter calculates the flow velocity of the water, and hence the flow rate, from the difference between the transit times of sound signals sent with and against the flow. Using these values together with those from the temperature sensors in the supply and return lines, the calculator unit records the heat energy consumed in kWh. As there is no moving part such as an impeller in the measuring section, there is no mechanical wear; this makes ultrasonic models longer-lasting than mechanical heat meters and more accurate at low flow rates. For the general working principle of heat meters and how they differ from heat cost allocators, see our Heat Meters page.

Applications of Ultrasonic Heat Meters

• Residential apartments and workplaces
• Residential complexes and apartment buildings
• Commercial buildings
• District heating and energy networks

They are particularly suitable for individual apartments, commercial premises and small to medium-sized installations; their compact design allows easy installation in tight spaces. For lines with higher flow rates, see our large-diameter heat meters (DN50–DN300, flanged).

Features of Ultrasonic Heat Meters

Features highlighted in the product descriptions (vary by model):

• All-metal, durable flow sensor construction
• Brass body for high pressure resistance
• Ultrasonic measuring technology with no moving parts
• High measuring accuracy even at low flow rates
• Long service life thanks to a wear-free design
• Special mirror design that filters out false signals
• Airfoil-shaped reflector design for laminar flow
• Self-cleaning flow channel; resistant to deposits, rust and clogging
• Heating-only or heating/cooling versions

Choosing the Right Size Between DN20 and DN40

The size should be chosen according to the design flow rate of the installation, not the pipe size. When replacing an existing meter, a model with the same body length (L) and connection size makes installation easier. The values below are taken from the Calmet PM02 series product pages; the body length may vary by brand and model.

DN20 is the most common size in apartments; you can compare the models in this size side by side in the DN20 heat meter category.

Communication Options: M-Bus, wM-Bus, LoRa

Ultrasonic heat meters can be read on the display as well as remotely. As stated in the product descriptions, the Novus Digitermo, Minol, Calmet and Cem models come with built-in wired M-Bus; wM-Bus/RF, LoRa or Modbus options can be ordered depending on the model. You can narrow down the list with the communication module filter. For bulk reading and billing, see our Remote Meter Reading and Billing service.

Installation Recommendations for Ultrasonic Heat Meters

• The arrow on the meter must point in the flow direction of the installation.
• Always clean the pipes before installation and fit a strainer upstream of the meter.
• For easy maintenance, valves are recommended before and after the meter and the strainer.
• Unless the manufacturer’s manual states otherwise, leave a straight pipe run of 10×DN upstream and 5×DN downstream of the meter.
• Open the valves slowly during commissioning.
• Check and clean the strainers periodically.
• In areas at risk of frost, drain the water from the meter; take protective measures for outdoor installation.

Ultrasonic Heat Meter Brands

Novus Digitermo stands out with compact, value-for-money models. Calmet ultrasonic heat meters are widely used in individual apartments and central system applications thanks to their economical prices and stable measuring performance; with threaded DN20–DN40 connection options, they are compatible with manifold-based installations.

Minol Zenner offers high-accuracy ultrasonic heat meter solutions of German origin that are compatible with remote reading. Danfoss provides durable and reliable metering solutions. Honeywell is preferred in commercial projects for its long battery life and stable measuring performance. Cem and İntegral are made in Türkiye and offer economical, well-balanced solutions.

Ultrasonic Heat Meter Prices and Choosing the Right Model

Ultrasonic heat meter prices depend on the size, the brand, the communication module (M-Bus, RF/wM-Bus), the sensor type and whether the meter is for heating only or heating/cooling. On our site you can compare models for different budgets in a single list and sort them by price. The choice should be based on the installation layout, the required flow rate and the communication infrastructure; our product specialists help you determine the right heat meter for your needs and avoid choosing the wrong product. For project purchases, you can use the Wholesale Order Form on the product pages.

For the working principle, types and size selection of heat meters, see our guide What Is a Heat Meter?

Frequently Asked Questions

Where are ultrasonic heat meters used?

They are used in central heating and cooling systems, including homes, residential complexes, commercial buildings and district heating. The threaded DN20–DN40 models in this category are intended especially for apartment installations with manifolds.

What are the advantages of ultrasonic heat meters?

As they have no moving parts, they are not subject to mechanical wear, they last longer and they provide high accuracy at low flow rates.

What should be considered when installing an ultrasonic heat meter?

The flow direction, a strainer upstream of the meter, the use of valves, straight pipe runs and regular cleaning of the strainers are important.

In which sizes are ultrasonic heat meters available?

This category includes threaded models in DN15, DN20, DN25, DN32 and DN40. For DN50 and larger, see the large-diameter heat meter category.

Can an ultrasonic heat meter be read remotely?

Yes. Models with M-Bus communication can be read remotely over a cable; wM-Bus/RF, LoRa or Modbus options are available depending on the model.

How often must an ultrasonic heat meter be re-verified?

Re-verification intervals for heat meters are set by national regulations and vary from country to country. Check your local regulations for periodic re-verification requirements; for more information, see our Heat Meter Re-verification and Calibration page.