View our full range of Kamstrup 403 Heat meters
The Kamstrup MULTICAL® 403 is an ultrasonic heat meter designed to measure the energy used in heating systems. It combines flow measurement with supply and return temperature measurement to calculate the amount of thermal energy being consumed.
The MULTICAL 403 is suitable for a wide range of applications, from apartments and smaller heating circuits through to commercial buildings, HVAC systems and larger plant installations.
A complete MULTICAL 403 heat meter measures three key values:
1. Water flow
The ultrasonic flow sensor measures the volume of water circulating through the heating system.
2. Flow temperature
A temperature sensor measures the temperature of the water entering the heating circuit.
3. Return temperature
A second matched temperature sensor measures the water returning from the circuit.
The meter then calculates the difference between the two temperatures and combines this with the measured flow rate to determine the amount of heat energy being transferred.
The result is normally displayed as kWh or MWh.
One of the most important parts of selecting a heat meter is choosing the correct qp flow rating.
The MULTICAL 403 range is available with nominal flow rates from approximately:
qp 0.6 m³/h through to qp 15 m³/h.
The meter should be sized according to the design flow rate of the system, rather than simply matching the pipe diameter.
For example, if the heating circuit has a calculated design flow of approximately 1.2 m³/h, a meter with a qp rating appropriate to that flow should be selected.
Oversizing a heat meter unnecessarily can reduce the quality of low-flow measurement, while undersizing it can create excessive pressure loss or exceed the permitted operating range.
Before ordering, establish:
Design flow rate in m³/h
Pipe size
Maximum operating temperature
Maximum system pressure
Heating or cooling application
Required installation position
Required communication output
Power supply requirements
Required connection type
Whether BMS integration is required
If you are unsure which meter is required, Western Automation can help select the appropriate Kamstrup meter from the system design information.
The MULTICAL 403 can be configured for installation in either the inlet/flow pipe or the outlet/return pipe.
This is important.
The meter configuration must correspond with the actual position of the ultrasonic flow sensor.
Do not simply install the meter into whichever pipe is most convenient without checking its configuration.
On the MULTICAL 403, a number of configuration parameters can be adjusted at the installation using the buttons on the front of the meter.
The arrow on the flow sensor body must point in the same direction as the water flow.
Before installing the meter:
Flush the heating system where required.
Ensure the pipework is free from debris.
Confirm the flow direction.
Confirm the meter is suitable for the system pressure and temperature.
Check the meter's configured flow/return position.
Install the flow sensor in accordance with Kamstrup's installation instructions.
Avoid creating unnecessary mechanical stress on the meter body or pipe connections.
The installation should also allow the display and calculator to remain accessible for commissioning, meter reading and future maintenance.
The MULTICAL 403 uses a matched pair of temperature sensors.
One measures the flow temperature and the other measures the return temperature.
Correct sensor positioning is essential because the meter calculates heat energy from the temperature difference between these two points.
The sensors should therefore be fitted into the correct flow and return positions and installed so they accurately measure the water temperature.
Do not interchange, extend or alter matched temperature sensors unless specifically permitted by the manufacturer's instructions.
Depending on the version ordered, MULTICAL 403 meters can be supplied with different power arrangements.
Once installed, verify that the display is operating correctly.
Check:
Flow direction
Flow/return configuration
Temperature readings
Instantaneous flow rate
Calculated energy
Any information or error codes
Communication module operation, where fitted
The MULTICAL 403 incorporates data logging and stores measurement information in permanent memory.
The front buttons can be used to cycle through the meter's available readings.
Depending on its configuration, information available can include:
The accumulated thermal energy consumed by the system.
Typically displayed in:
kWh or MWh
The total volume of water that has passed through the meter.
Usually displayed in:
m³
The current heating-water supply temperature.
The temperature of the water returning from the heating circuit.
The difference between the flow and return temperatures.
For example:
Flow temperature = 70°C
Return temperature = 50°C
ΔT = 20 K
The MULTICAL 403 can measure the current water flow rate through the ultrasonic flow sensor.
This can be particularly useful during commissioning and when diagnosing HVAC system performance.
Depending on configuration, the meter can also provide information relating to the instantaneous thermal power being transferred.
A common question is:
Can a Kamstrup MULTICAL 403 be connected to a Building Management System?
Yes.
MULTICAL 403 can be equipped with different communication modules depending on the BMS or metering system being used.
Communication options can include:
M-Bus
Wireless M-Bus
Modbus
BACnet
Analogue outputs
Other Kamstrup communication solutions
The exact module should be selected when ordering the meter.
A separate flow sensor is not necessarily required simply because the BMS needs a flow reading.
The MULTICAL 403 already measures water flow using its ultrasonic flow sensor.
With the appropriate communication module, values from the meter can be transferred to the BMS.
Depending on the selected interface and configuration, this can include information such as:
Energy
Volume
Flow rate
Flow temperature
Return temperature
Temperature difference
Power
Meter status
This can avoid installing an additional flow sensor solely for BMS monitoring.
For installations requiring an analogue signal rather than a digital building-services protocol, Kamstrup offers an analogue output module for MULTICAL 403.
The Kamstrup HC-003-40 module provides two galvanically isolated current outputs.
The outputs can be configured for:
0–20 mA
or
4–20 mA
This can be particularly useful where an existing BMS requires conventional analogue inputs rather than M-Bus, Modbus or BACnet communications.
M-Bus is commonly used for energy metering installations where multiple heat, water or electricity meters are connected to a central data collection system.
A MULTICAL 403 equipped with the appropriate M-Bus module can provide remote meter readings without requiring someone to physically access the meter.
For building-management applications, MULTICAL 403 can also be specified with communication suitable for integration into systems using protocols such as:
Modbus
and
BACnet
This makes the meter particularly useful for commercial buildings where heat consumption and HVAC performance are monitored centrally.
Always check the flow-direction arrow on the flow sensor.
Incorrect temperature-sensor positioning can cause incorrect energy calculations.
Ensure the meter configuration agrees with the actual installation position.
Select the meter according to the system design flow rather than pipe size alone.
Determine the BMS protocol before ordering the meter.
The temperature sensors must accurately measure the heating-water temperatures.
The MULTICAL 403 contains diagnostic monitoring. If the meter displays an INFO condition, the associated information code should be checked to identify the cause.
Unlike traditional mechanical meters, the MULTICAL 403 uses ultrasonic technology to measure water flow.
This provides several advantages for heating applications, including:
No traditional mechanical measuring impeller
Accurate flow measurement
Wide measuring range
Low-flow measurement capability
Long-term measurement stability
Integrated diagnostics
Remote reading capability
Data logging
BMS integration options
Typical applications include:
Commercial heating systems
Apartment heat metering
Landlord energy billing
District heating
Schools and universities
Hospitals
Office buildings
Hotels
Plant rooms
HVAC systems
Energy-management systems
Building Management Systems
Western Automation supplies Kamstrup MULTICAL 403 ultrasonic heat meters for commercial and industrial heating applications.
Choosing the correct meter depends on the system flow rate, pipe size, installation arrangement and required communication method.
Our technical sales team can help identify the correct meter and communication option for your application.
When enquiring, provide:
Pipe size + design flow rate + flow/return temperatures + required BMS protocol.
This allows us to identify the most suitable Kamstrup MULTICAL 403 configuration for your installation.
Sep 25 2026 | Guides and How-to