The flow of water, e.g. in the water heating system, cold and hot water in the house, monitoring of leaking water at a recreational facility, and such like, the speed flowmeters can be used; they are fitted with an output for scanning the instantaneous flow.
In velocity flowmeters, the flowing fluid acts on a set of blades on a rotor that spins. The revolutions of the rotor are transmitted to the counter, or they are scanned and electronically evaluated. Impurities in the liquid may cause damage to the flowmeter, so this type requires the installation of a fine filter to reduce the risk of a fault. A disadvantage of velocity flowmeters is their permanent operating pressure loss caused by the hydraulic resistance of the revolving part.
If you want to meter the fluid flow in the primary circuit of the solar system, you should use a flowmeter with a higher temperature resistance. The temperature sensors and flowmeters for metering in solar system circuits must be resistant to operating temperatures of at least 120 °C (the temperature sensor on the collector up to 180 °C).
A suitable flowmeter is the AV23 connected to the C-AM-0600I module, which can simultaneously measure the temperature of the medium.
Metering the water-supplied heat (the heat produced by the heat pump, the hot water for domestic appliances, etc.) can be done in combination of the flow measurement with two added temperature sensors (for the hot water outlet and the return flow) and the heat supplied is calculated (by the function block) in the application software. The temperature sensors can also be utilized for the control and monitoring of the system.
Metering the heat generated by the solar system can be done by the AV23 flowmeter, where a second temperature can be added, and the supplied or consumed heat is calculated (by the function block) in the application software. An advantage of this flowmeter is a greater range of temperatures and viscosity of the medium, which makes it suitable for the primary circuit of the solar system. Pressure losses in primary circuits of solar systems can fluctuate during the operation due to a considerable dependence of antifreeze mixtures viscosity on temperature; if the power of circulation pumps is fixed, the flow in the circuit can fluctuate up to 30 %.
When selecting a flowmeter, you should also take into account the parameters of the distribution system, especially the required maximum flow of water. For more information about the guidelines for the distribution and control of water, see the Chapter Water - control.