Who needs a flow meter that reads zero?
Retrofit Service saves up to 65% on energy costs in HVAC applications with Katronic clamp-on flow meters.
Clamp-on Ultrasonic Measurement for Demanding Heating, Ventilation, and Air Conditioning Systems
The heating, ventilation, and air conditioning retrofit specialist "Retrofit Service" relies on Katronic’s non-invasive clamp-on flow meters for demanding sequencing and variable flow applications, where energy costs can be reduced by up to 60–65% in various instantaneous water heater and air conditioning systems.
If a system with constant flow rates of 100% and continuously running pumps is replaced with a variable-flow design, the system’s flow rates can vary between 15% and 100% depending on demand. By adjusting pump speeds to precisely match system demand, significant savings can be achieved, particularly in large, multi-level environments with multiple users.
In standard primary and secondary heating systems, hot water is continuously pumped through the network, with the flow to individual consumers within the network controlled by three-way valves. Regardless of the position of these valves, the system flow rate remains constant at 100%, and the pumps run at full power regardless of demand, resulting in energy waste. Retrofit’s technical approach is to replace fixed-speed pumps with variable-speed pumps and install variable-flow valves to regulate the flow to the various zones of a building. If the system is precisely balanced, the “waste” of hot water that merely circulates in the loop instead of flowing through one of the heating zones should be as close to zero as possible.
Every automated system relies on feedback from sensors in the process to a central control unit. The most important control elements are the feedback on the flow rates of the secondary heating loop and the flow rates of the decoupling system. Retrofit had previously tried various approaches, including several technologies—a turbine flow meter had too much hysteresis, a paddle wheel flow meter could not measure in both directions, and a magnetic-inductive flow meter lacked the required accuracy at low flow rates.
Katronic’s clamp-on ultrasonic flow meter has proven to be the ideal solution. Since the flow meter can measure flow rates as low as 0.01 meters per second (and up to 25 meters per second) and measures in both directions with the same sensitivity and accuracy, it provided exactly what Retrofit needed: a “reliable zero point”. The flow measurements from the decoupling pipe are used to control the speed of the primary pumps and, ultimately, the combustion rate in the boilers so that it always matches the flow rate of the secondary pumps (distribution pumps). The savings achieved through the Retrofit system are, in some cases, substantial: a large Irish installation with 350 users generated savings of €500,000.00 in the first year alone.
Katronic’s product range includes both portable and permanently installed flow measurement systems, all of which feature easy installation, visual and audible commissioning aids, and high measurement accuracy. A system can be tested with a portable device before a permanent monitoring system is installed. The ability to provide potential users with dual-channel meters—essentially two flow meters in a single housing—makes them exceptionally cost-effective.
Steve Chadwick, a director at Retrofit Services, comments: “We’ve been using Katronic devices for some time now (our oldest meter is over 15 years old); we have several flow meters in use, and they’ve never failed. It’s an unusual requirement for a flow meter—to measure zero flow—but this need is driven by customers as the pressure for greater energy savings increases. We’re very satisfied with everything Katronic has delivered to us so far, and their technical support is excellent.”
