Cooling Meters (Hybrid Heating and Cooling Meters)

A cooling meter measures the cooling energy used by each dwelling unit in fan-coil and central cooling systems. The models in this category are hybrid meters: the same device records heating and cooling energy in two separate registers. For apartments there are DN20–DN40 threaded models (Minol Zenner C5 IUF, Calmet PM02, CEM CM-HR, İntegral UK-PLUS, Novus Digitermo DTL), and for high-flow lines there are DN50–DN300 flanged Minol Zenner IUF and Calmet PM02 models.

How Does a Cooling Meter Measure?

The measuring principle is the same as for a heat meter: the calculator unit combines the volume of water passing through the flow sensor with the temperature difference measured by the two temperature sensors on the supply and return lines, and totalizes the energy in kWh (MWh or GJ, depending on the model). The difference lies in the direction of the temperatures: in cooling, the supply water is colder than the return water. According to the Minol ZENNER manual, the temperature difference and the instantaneous power are shown on the display with a minus sign during cooling. In hybrid meters, cooling energy accumulates in a register separate from heating energy.

When Do You Need a Hybrid (Heating + Cooling) Meter?

• Two-pipe fan-coil systems: the same line carries hot water in winter and chilled water in summer; a hybrid meter measures both seasons with a single device.
• Central systems that provide both heating and cooling (e.g. heat pump systems).
• Residential complexes, offices and shopping malls where cooling costs are also allocated by consumption.

If the installation is for heating only, the cooling register is not used; in that case you can browse all models in the ultrasonic heat meters category. Meters built for heating only, such as the Danfoss SonoSafe 10, do not record cooling energy.

Cooling Measurement by Model

Approval and Re-verification

The European Measuring Instruments Directive (MID) covers heat meters; cooling energy measurement is outside the scope of this directive. For this reason, some manufacturers obtain a separate national type approval for cooling measurement: for the Minol ZENNER C5 IUF, heat measurement is certified under the MID (DE-12-MI004-PTB010) and cooling measurement under a German national approval (DE-20-M-PTB-0046). Check your local regulations for periodic re-verification requirements; general information on heat meter re-verification is available on our re-verification and calibration page.

How to Read the Cooling Register

In hybrid meters, cooling energy is displayed as a separate value. On the Minol ZENNER C5 and the CEM CM-HR, the cooling value is shown with a snowflake symbol; on the Calmet PM02, it appears in the 1-USER loop after the heating energy. For a step-by-step explanation, see our How to Read a Heat Meter guide; the working principle of heat meters and size selection are explained in the What Is a Heat Meter? guide.

Frequently Asked Questions

What is a cooling meter?

A meter that measures, in kWh, the cooling energy used by a dwelling unit in a cooling system, calculating it from the volume of water passing through the meter and the supply–return temperature difference.

What is a hybrid heat meter?

It is a single device that measures both heating and cooling energy and keeps the two in separate registers. In two-pipe fan-coil systems, one meter measures both seasons.

Does a heating-only heat meter measure cooling?

Meters built for heating only do not record cooling energy. If cooling is to be measured as well, choose a hybrid or cooling version.

Is cooling measurement MID-approved?

The MID (European Measuring Instruments Directive) covers heat meters, not cooling measurement. That is why some manufacturers obtain a separate national type approval for cooling measurement; for example, cooling measurement on the Minol ZENNER C5 IUF is certified under German approval no. DE-20-M-PTB-0046.

Where is the cooling register shown on the display?

In hybrid meters, cooling energy is shown as a value separate from heating, marked with a snowflake symbol on most models. A model-by-model explanation is available in our How to Read a Heat Meter guide.