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In a modern HVAC system flow meters are critical.

We have all heard the saying, “If you can’t measure it, you can’t do anything about it!” To paraphrase that, we can also say, “If you can’t measure it, you can’t charge for it”, and so it is with HVAC.

Without some form of quantification coupled with a payment mechanism, end users have no incentive to monitor their energy consumption. Even if costs are split evenly, end-users may end up paying for more or less than their usage, leading to hard feelings and animosity.

This is where flow meters are invaluable. In a smart building HVAC system, they contribute to energy savings, maintenance and repair planning and energy costing calculations and billing. 

HVAC system flow meters

What do Flow Meters do

Flow meters are devices that measure the amount of liquid, gas or vapour passing through a pipe system. Some flow meters require the substance to pass through them; others use sensors that sense the fluid motion and convert it into a usable signal.

Whatever flow meter is used, the ultimate goal is to measure either the flow rate, total amount, or both. 

Why do we need flow measurement?

In today’s world, there is ever-increasing pressure to use resources wisely. Additionally, with increasing energy costs, economies need to be implemented; and this is particularly true in modern smart buildings.

Building management systems (BMS) require significant numbers of metering points for the complex control of plant optimisation for tenant comfort. Furthermore, there is a need to monitor equipment, building and system performance. There is more and more a demand for user-pay systems where individual tenants are charged for their energy usage.

Monitoring and controlling equipment

The high demands made of modern building management systems mean that data is required almost instantaneously for feedback loops to achieve extremely high levels of performance.

HVAC system flow meters, with the associated data transfer systems, play a vital role in these loops allowing automation systems to receive real-time data. The data can then be used to optimise the system and report on equipment, energy consumption and temperatures.

In a chilled water system, this would mean instantly adjusting water distribution, controlling return temperatures to maintain delta T values, and controlling cooling units.

With these controls in place, energy waste is limited, system efficiency is improved and costs are controlled. 

HVAC system flow meters

Operational efficiencies

Apart from system monitoring and control, the data received from flow meters can be used to calculate efficiencies in various units. For example, boiler efficiency and chiller Coefficient of Performance (COP) or Energy Efficiency Ratio (EER) can be calculated to monitor and validate performance. 

Additionally, readings can provide information on poor performance areas indicating damage, leaks and other issues which result in poor performance and increased costs.

HVAC system flow meters

Objective allocation of costs 

Traditionally, flow meters have been used to meter overall consumption and the data used for consumption and costing. However, in modern buildings, flow meters can provide real-time consumption and cost data to individual tenants, helping them control their own consumption and costs and conserve energy where they can.

This submetering identifies excess use and wastage which can then be rectified.

Effectively utilising flow meter data is critical to equipment monitoring and control, calculating efficiencies and accurately allocating costs on an equitable basis. The successful implementation of flow measurement is essential to maintain the reliability and accuracy of your HVAC system for now and into the future.

If you need further information or assistance with a project, call ACS.