Ultrasonic water meter
Helvatron H2O
For cold and hot water in residential, commercial and industrial buildings, for billing and for energy management to ISO 50001. Threaded from DN15 to DN40, flanged from DN50, all with ultrasonic measurement and an internal data logger.
Applications
Where is the H2O installed?
Wherever water volumes need to be measured reliably: in the distribution to flats and floors, at the service connection, in hot-water production and for process water.
- Indoors, or outdoors in a pit or meter box; rated IP68
- Any installation position: horizontal, vertical, rising or falling pipework
- No straight inlet or outlet sections needed from DN15 to DN40
- Records forward and reverse volume separately; detects leaks and air in the pipe
- Nominal pressure PN16 or PN25, temperature classes T30 to T90
Typical projects
Water meters for flats: DN15 or DN20 with M-Bus, read by an M-Bus master in the plant room.
Service connection or zone: flanged from DN50, in a pit, read via LoRa with no cable to the metering point.
Industry and energy management: RS-485 and Modbus RTU, connected directly to the controller.
Measuring principle and data path
How does the H2O measure, and how do the values reach the control system?
Two ultrasonic transducers send pulses with and against the flow. Self-cleaning reflectors guide the sound through the measuring tube. The difference in transit time is a measure of the flow velocity. From this, the meter calculates the flow rate and volume and stores hourly, daily and monthly values in its own memory.
- Prepare the pipeThe meter is fitted in the cold-water pipe between two shut-off valves. From DN15 to DN40, the H2O needs no straight inlet or outlet sections.
- Install the meterDN15 to DN40 with threaded connections, from DN50 with flanges. The arrow on the meter shows the flow direction; any installation position is permitted.
- Water flowsWater flows through the measuring tube of the meter to the distribution pipework in the building.
- Measure with ultrasoundTwo transducers alternately send pulses with and against the flow. The pulse travelling with the flow arrives sooner.
- Calculate flow rateThe transit time difference gives the flow velocity and hence the flow rate. The meter totalises the volume and stores hourly, daily and monthly values.
- Transmit dataAn M-Bus master such as the EMU M-Center reads the meter by its secondary address. Other versions transmit via RS-485 (Modbus RTU) or LoRa.
- Analyse in the control systemThe M-Center forwards the values via MQTT, BACnet IP, Modbus TCP or CSV to the building management and energy management systems.
More on the technology: Ultrasonic flow measurement · M-Bus
Connection types
Threaded up to DN40, flanged from DN50
Length and connection type depend on the nominal size. When selecting a meter, the flow rate matters, not just the pipe diameter.
Threaded connection
G 3/4 B to G 2 B, lengths 110 to 300 mm. Q3 from 2.5 to 16 m³/h. Typical for flats, floors and smaller commercial units.
Flanged connection
Lengths 200 to 600 mm, Q3 from 25 to 4000 m³/h, dynamic range up to R800. For service connections, zones, distribution networks and industry.
Choose the nominal size
Which values apply to your nominal size?
Select a nominal size to see the connection, length, flow rates and the interfaces for which a part number is available.
Helvatron H2O DN15 Threaded connection
- Connection
- Thread G 3/4 B
- Length
- 110 mm
- Permanent flow rate Q3
- 2.5 m³/h
- Overload flow rate Q4
- 3.125 m³/h
- Minimum flow rate Q1
- 0.01 m³/h (R250) · 6.25 l/h (R400)
- Ratio Q3/Q1
- R250, R400, R500
- Height
- 81 mm
- Interfaces with part number
- M-Bus
WAAE.20C.ABM
RS-485 (Modbus RTU)WAAE.20C.ABMO
LoRaWAAE.20C.ABL
NB-IoT: in all nominal sizes
Helvatron H2O DN20 Threaded connection
- Connection
- Thread G 1 B
- Length
- 130 mm
- Permanent flow rate Q3
- 4.0 m³/h
- Overload flow rate Q4
- 5 m³/h
- Minimum flow rate Q1
- 0.016 m³/h (R250) · 10 l/h (R400)
- Ratio Q3/Q1
- R250, R400, R500
- Height
- 85 mm
- Interfaces with part number
- M-Bus
WABG.20C.ABM
RS-485 (Modbus RTU)WABG.20C.ABMO
LoRaWABG.20C.ABL
NB-IoT: in all nominal sizes
Helvatron H2O DN25 Threaded connection
- Connection
- Thread G 1 1/4 B
- Length
- 260 mm
- Permanent flow rate Q3
- 6.3 m³/h
- Overload flow rate Q4
- 7.875 m³/h
- Minimum flow rate Q1
- 0.025 m³/h (R250) · 15.75 l/h (R400)
- Ratio Q3/Q1
- R250, R400, R500
- Height
- 129/130 mm
- Interfaces with part number
- M-Bus
WACI.20C.ABM
RS-485 (Modbus RTU)WACI.20C.ABMO
LoRaWACI.20C.ABL
NB-IoT: in all nominal sizes
Helvatron H2O DN32 Threaded connection
- Connection
- Thread G 1 1/2 B
- Length
- 260 mm
- Permanent flow rate Q3
- 10 m³/h
- Overload flow rate Q4
- 12.5 m³/h
- Minimum flow rate Q1
- 0.04 m³/h (R250) · 25 l/h (R400)
- Ratio Q3/Q1
- R250, R400, R500
- Height
- 144 mm
- Interfaces with part number
- M-Bus
WADJ.20C.ABM
RS-485 (Modbus RTU)WADJ.20C.ABMO
LoRaWADJ.20C.ABL
NB-IoT: in all nominal sizes
Helvatron H2O DN40 Threaded connection
- Connection
- Thread G 2 B
- Length
- 300 mm
- Permanent flow rate Q3
- 16 m³/h
- Overload flow rate Q4
- 20 m³/h
- Minimum flow rate Q1
- 0.064 m³/h (R250) · 40 l/h (R400)
- Ratio Q3/Q1
- R250, R400, R500
- Height
- 144/172 mm
- Interfaces with part number
- M-Bus
WAEL.20C.ABM
RS-485 (Modbus RTU)WAEL.20C.ABMO
LoRaWAEL.20C.ABL
NB-IoT: in all nominal sizes
Helvatron H2O DN50 Flanged connection
- Connection
- Flange DN50
- Length
- 200 mm
- Permanent flow rate Q3
- 25 m³/h
- Overload flow rate Q4
- 31.25 m³/h
- Minimum flow rate Q1
- 0.06 m³/h
- Ratio Q3/Q1
- R400, R800
- Height
- 180/183 mm
- Interfaces with part number
- M-Bus
WAFFM.20C.ABM
RS-485 (Modbus RTU)WAFFM.20C.ABMO
LoRaWAFFM.20C.ABL
NB-IoT: in all nominal sizes
Helvatron H2O DN65 Flanged connection
- Connection
- Flange DN65
- Length
- 200 mm
- Permanent flow rate Q3
- 40 m³/h
- Overload flow rate Q4
- 50 m³/h
- Minimum flow rate Q1
- 0.125 m³/h
- Ratio Q3/Q1
- R400, R800
- Height
- 197/200 mm
- Interfaces with part number
- M-Bus
WAGFN.20C.ABM
RS-485 (Modbus RTU)WAGFN.20C.ABMO
LoRaWAGFN.20C.ABL
NB-IoT: in all nominal sizes
Helvatron H2O DN80 Flanged connection
- Connection
- Flange DN80
- Length
- 225 mm
- Permanent flow rate Q3
- 63 m³/h
- Overload flow rate Q4
- 78.25 m³/h
- Minimum flow rate Q1
- 0.1575 m³/h
- Ratio Q3/Q1
- R400, R800
- Height
- 222/235 mm
- Interfaces with part number
- M-Bus
WAHFO.20C.ABM
RS-485 (Modbus RTU)WAHFO.20C.ABMO
LoRaWAHFO.20C.ABL
NB-IoT: in all nominal sizes
Helvatron H2O DN100 Flanged connection
- Connection
- Flange DN100
- Length
- 250 mm
- Permanent flow rate Q3
- 100 m³/h
- Overload flow rate Q4
- 125 m³/h
- Minimum flow rate Q1
- 0.25 m³/h
- Ratio Q3/Q1
- R400, R800
- Interfaces with part number
- M-Bus
WAIFP.20C.ABM
RS-485 (Modbus RTU)WAIFP.20C.ABMO
LoRaWAIFP.20C.ABL
NB-IoT: in all nominal sizes
Helvatron H2O DN125 Flanged connection
- Connection
- Flange DN125
- Length
- 250 mm
- Permanent flow rate Q3
- 160 m³/h
- Overload flow rate Q4
- 200 m³/h
- Minimum flow rate Q1
- 0.4 m³/h
- Ratio Q3/Q1
- R400, R800
- Interfaces with part number
- M-Bus
WAJFQ.20C.ABM
NB-IoT: in all nominal sizes
Helvatron H2O DN150 Flanged connection
- Connection
- Flange DN150
- Length
- 300 mm
- Permanent flow rate Q3
- 250 m³/h
- Overload flow rate Q4
- 312.5 m³/h
- Minimum flow rate Q1
- 0.625 m³/h
- Ratio Q3/Q1
- R400, R800
- Interfaces with part number
- M-Bus
WAKFS.20C.ABM
RS-485 (Modbus RTU)WAKFS.20C.ABMO
NB-IoT: in all nominal sizes
Helvatron H2O DN200 Flanged connection
- Connection
- Flange DN200
- Length
- 350 mm
- Permanent flow rate Q3
- 400 m³/h
- Overload flow rate Q4
- 500 m³/h
- Minimum flow rate Q1
- 1 m³/h
- Ratio Q3/Q1
- R400, R800
- Interfaces with part number
- M-Bus
WALFU.20C.ABM
NB-IoT: in all nominal sizes
Helvatron H2O DN250 Flanged connection
- Connection
- Flange DN250
- Length
- 450 mm
- Permanent flow rate Q3
- 630 m³/h
- Overload flow rate Q4
- 787.5 m³/h
- Minimum flow rate Q1
- 1.575 m³/h
- Ratio Q3/Q1
- R400, R800
- Interfaces with part number
- M-Bus
WAMFV.20C.ABM
NB-IoT: in all nominal sizes
Helvatron H2O DN300 Flanged connection
- Connection
- Flange DN300
- Length
- 500 mm
- Permanent flow rate Q3
- 1000 m³/h
- Overload flow rate Q4
- 1250 m³/h
- Minimum flow rate Q1
- 2.5 m³/h
- Ratio Q3/Q1
- R400, R800
- Interfaces with part number
- M-Bus
WANFZ.20C.ABM
NB-IoT: in all nominal sizes
Helvatron H2O DN350 Flanged connection
- Connection
- Flange DN350
- Length
- 500 mm
- Permanent flow rate Q3
- 1000 m³/h
- Overload flow rate Q4
- 1250 m³/h
- Minimum flow rate Q1
- 2.5 m³/h
- Ratio Q3/Q1
- R400, R800
- Interfaces with part number
- M-Bus
WAOF0.20C.ABM
NB-IoT: in all nominal sizes
Helvatron H2O DN400 Flanged connection
- Connection
- Flange DN400
- Length
- 600 mm
- Permanent flow rate Q3
- 1600 m³/h
- Overload flow rate Q4
- 2000 m³/h
- Minimum flow rate Q1
- 4 m³/h
- Ratio Q3/Q1
- R400, R800
- Interfaces with part number
- M-Bus
WAPF0.20C.ABM
NB-IoT: in all nominal sizes
Helvatron H2O DN500 Flanged connection
- Connection
- Flange DN500
- Length
- 600 mm
- Permanent flow rate Q3
- 2500 m³/h
- Overload flow rate Q4
- 3125 m³/h
- Minimum flow rate Q1
- 6.25 m³/h
- Ratio Q3/Q1
- R400, R800
- Interfaces with part number
- M-Bus
WARF0.20C.ABM
NB-IoT: in all nominal sizes
Helvatron H2O DN600 Flanged connection
- Connection
- Flange DN600
- Length
- 600 mm
- Permanent flow rate Q3
- 4000 m³/h
- Overload flow rate Q4
- 5000 m³/h
- Minimum flow rate Q1
- 10 m³/h
- Ratio Q3/Q1
- R400, R800
- Interfaces with part number
- No part number available; please enquire.
NB-IoT: in all nominal sizes
The current technical documentation is binding.
All nominal sizes as a table
| Nominal size | Connection | Q3 | Q4 | Q1 | L |
|---|---|---|---|---|---|
| DN15 | G 3/4 B | 2.5 | 3.125 | 0.01 | 110 mm |
| DN20 | G 1 B | 4.0 | 5 | 0.016 | 130 mm |
| DN25 | G 1 1/4 B | 6.3 | 7.875 | 0.025 | 260 mm |
| DN32 | G 1 1/2 B | 10 | 12.5 | 0.04 | 260 mm |
| DN40 | G 2 B | 16 | 20 | 0.064 | 300 mm |
| DN50 | DN50 | 25 | 31.25 | 0.06 | 200 mm |
| DN65 | DN65 | 40 | 50 | 0.125 | 200 mm |
| DN80 | DN80 | 63 | 78.25 | 0.1575 | 225 mm |
| DN100 | DN100 | 100 | 125 | 0.25 | 250 mm |
| DN125 | DN125 | 160 | 200 | 0.4 | 250 mm |
| DN150 | DN150 | 250 | 312.5 | 0.625 | 300 mm |
| DN200 | DN200 | 400 | 500 | 1 | 350 mm |
| DN250 | DN250 | 630 | 787.5 | 1.575 | 450 mm |
| DN300 | DN300 | 1000 | 1250 | 2.5 | 500 mm |
| DN350 | DN350 | 1000 | 1250 | 2.5 | 500 mm |
| DN400 | DN400 | 1600 | 2000 | 4 | 600 mm |
| DN500 | DN500 | 2500 | 3125 | 6.25 | 600 mm |
| DN600 | DN600 | 4000 | 5000 | 10 | 600 mm |
Q3, Q4, Q1 in m³/h. The current technical documentation is binding.
Help with sizing: Choosing the right nominal size
Interfaces and data
How is the H2O read?
You specify the interface via the part number. The optical D0 interface is always available for on-site configuration and reading.
- M-Bus (wired)
- Bus and protocol in one. The meter can optionally be powered via the M-Bus. More
- Wireless M-Bus
- Radio telegrams in S1, T1 and OMS mode.
- RS-485 · Modbus RTU
- RS-485 as the physical interface, Modbus RTU as the protocol. More
- LoRa, 868 MHz
- Radio to LoRa gateways. More
- NB-IoT
- Via the mobile network in all nominal sizes, without a radio network of your own. More
Values provided by the H2O
- Total volume
- Forward volume
- Reverse volume
- Volume of pulse inputs 1 and 2
- Maximum and minimum flow rate with date
- Maximum and minimum temperature with date (if used)
- Error-free operating time
- Error code
- Time above 1.2 × Q4 and below Q1
Alarms
- Low battery
- Air in pipe
- Leak detection
The serial number is also printed as a QR code on the meter. This makes it quick to set up the meter in energy management systems such as Joulio-Web.
Technical data
Helvatron H2O at a glance
- Nominal sizes
- DN15–DN600 · Threaded DN15–DN40, flanged from DN50
- Approvals and standards
- MID (class 2) · MID module D, METAS-Cert · CE · WRAS · OIML R 49 · EN 14154 · ISO 4064
- Accuracy
- Class 2 (OIML R 49)
- Dynamic range
- Q3/Q1 R250, R400 or R500 (DN15–DN40); flanged versions R400 or R800
- Temperature classes
- T30, T50, T70, T90
- Medium temperature
- Standard 0.1 °C to 50 °C; on request 1 °C to 70 °C or 90 °C
- Ambient temperature
- +5 °C … +65 °C
- Nominal pressure
- PN16 / PN25
- Ingress protection
- IP68
- Installation location
- indoors, or outdoors in a pit or meter box
- Installation position
- any position: horizontal, vertical, rising or falling pipe
- Straight inlet/outlet sections
- DN15–DN40: no straight inlet or outlet sections required; larger sizes as per the installation instructions
- Wetted parts
- Lead-free brass or stainless steel (wetted parts)
- Display
- 8-digit LCD
- Power supply
- 3.6 V battery, battery life 10 to 16 years. Option: external supply 12…42 V DC or power via M-Bus
- Interfaces
- M-Bus · Wireless M-Bus (S1, T1, OMS) · RS-485 (Modbus RTU) · LoRa 868 MHz · NB-IoT · Optical interface D0
The current technical documentation is binding.
Part numbers
Part numbers by nominal size and interface
Shown for temperature class T50 (code letter C). For T70, replace it with H, for example WABG.20H.ABM. T90 on request.
| Nominal size | M-Bus | RS-485 (Modbus RTU) | LoRa |
|---|---|---|---|
| DN15 | WAAE.20C.ABM | WAAE.20C.ABMO | WAAE.20C.ABL |
| DN20 | WABG.20C.ABM | WABG.20C.ABMO | WABG.20C.ABL |
| DN25 | WACI.20C.ABM | WACI.20C.ABMO | WACI.20C.ABL |
| DN32 | WADJ.20C.ABM | WADJ.20C.ABMO | WADJ.20C.ABL |
| DN40 | WAEL.20C.ABM | WAEL.20C.ABMO | WAEL.20C.ABL |
| DN50 | WAFFM.20C.ABM | WAFFM.20C.ABMO | WAFFM.20C.ABL |
| DN65 | WAGFN.20C.ABM | WAGFN.20C.ABMO | WAGFN.20C.ABL |
| DN80 | WAHFO.20C.ABM | WAHFO.20C.ABMO | WAHFO.20C.ABL |
| DN100 | WAIFP.20C.ABM | WAIFP.20C.ABMO | WAIFP.20C.ABL |
| DN125 | WAJFQ.20C.ABM | No part number with this interface. | No part number with this interface. |
| DN150 | WAKFS.20C.ABM | WAKFS.20C.ABMO | No part number with this interface. |
| DN200 | WALFU.20C.ABM | No part number with this interface. | No part number with this interface. |
| DN250 | WAMFV.20C.ABM | No part number with this interface. | No part number with this interface. |
| DN300 | WANFZ.20C.ABM | No part number with this interface. | No part number with this interface. |
| DN350 | WAOF0.20C.ABM | No part number with this interface. | No part number with this interface. |
| DN400 | WAPF0.20C.ABM | No part number with this interface. | No part number with this interface. |
| DN500 | WARF0.20C.ABM | No part number with this interface. | No part number with this interface. |
NB-IoT is available in all nominal sizes. Wireless M-Bus and sizes not listed in this table are available on request.
Questions
Frequently asked questions about the H2O
Does the H2O need straight inlet and outlet sections?
Not from DN15 to DN40. For larger sizes, the installation instructions apply. The meter can be installed in any position.
Which nominal sizes are threaded and which are flanged?
DN15, DN20, DN25, DN32 and DN40 have threaded connections from G 3/4 B to G 2 B. From DN50 to DN600, the H2O is flanged.
Can the H2O measure hot water?
Yes. The standard medium temperature range is 0.1 to 50 °C (T50). Versions up to 70 °C or 90 °C are available on request.
How long does the battery last?
The 3.6 V battery lasts 10 to 16 years, depending on interface and reading interval. Alternatively, it can be powered by an external 12 to 42 V DC supply or via the M-Bus.
Which approvals does the H2O have?
MID class 2 with CE marking, production certified to MID module D by METAS-Cert, and WRAS approval. It complies with OIML R 49, EN 14154 and ISO 4064.
Is the H2O available with NB-IoT?
Yes, in all nominal sizes. The meter then transmits over the mobile network, with no bus cable and no gateway of your own.
Does the meter detect reverse flow?
Yes. It records forward and reverse volume separately and also reports leaks and air in the pipe.
A project with the H2O?
Tell us the nominal sizes, quantity and interface, and we will send you the data sheet, part numbers and a quotation.