An ultrasonic meter has no moving parts, so it does not suffer mechanical wear in operation and maintains its accuracy throughout its service life. It achieves lower pressure losses, has a wider dynamic range (qp/qi up to 1:100), and can detect very low flow rates from 1 l/h. At the same time, it is insensitive to dirt and suspended particles in the heating water, to which mechanical meters are prone.

The qp 0.6 m³/h version is designed for lower flow rates – typically for flats with lower heat loss, low-energy and passive buildings, or circuits with a heat pump. The maximum flow rate qs is 1.2 m³/h, and continuous operation above this value is not permitted. If the design flow rate exceeds 1 m³/h or approaches this limit, choose the qp 1.5 m³/h version (standard flat circuits). The qp 2.5 m³/h version is intended for flats with higher heat loss and small commercial premises. If the meter is undersized, it operates at the limit of overload and its service life is reduced; if oversized, it may lack resolution in the lower part of the flow curve.

wM-Bus (Wireless M-Bus) is the wireless version of the M-Bus standard for remote meter reading. The meter transmits a radio telegram at regular intervals, which is received by an M-Bus receiver, concentrator, or mobile device (notebook, tablet with reading application). Communication takes place in the licence-free 868 MHz band according to the Open Metering Standard (OMS) and is one-way – the meter only transmits, it does not receive. The main advantage over wired M-Bus is that you do not need to run a bus cable to each meter, which is particularly suitable in existing apartment buildings.

Standard mode (walk-by) sends data every 64 seconds and is optimised for walk-by reading by a technician with a handheld receiver, who only needs to pass by the flat door or shaft. In this mode, the battery lasts up to 11 years. Rapid mode (drive-by) sends data every 14 seconds and is intended for readout from a passing vehicle, where the time available to capture the telegram is shorter. The higher transmission frequency reduces battery life to approximately 7 years. The mode is set during commissioning according to the planned readout method.

The meter can be installed in any position – horizontally, vertically on a riser or downpipe, or even inverted above the pipe centreline. This orientation independence is due to the ultrasonic measurement principle, which does not require straight pipe lengths upstream and downstream of the meter to the same extent as mechanical water meters.

For the wM-Bus version, the battery lasts up to 11 years in standard mode (walk-by, 64 s interval) and up to 7 years in rapid mode (drive-by, 14 s interval) under standard operating conditions. Higher ambient temperatures shorten battery life – therefore operation below 35 °C is recommended. The battery cannot be replaced by the user during operation; replacement is carried out by the manufacturer's service laboratory.

Yes. The SHARKY 774 compact is approved in accordance with the MID directive (DE-13-MI004-PTB008) in accuracy class 2 and for cooling according to PTB K7.2. It therefore meets the requirements for a legally controlled meter used for billing of heat and cooling. The meter belongs to ambient class E2 (electromagnetic immunity) and M2 (mechanical immunity), making it less susceptible to interference from PWM circulation pumps and similar sources.