ENERGY SAVING EQUIPMENT
What do we monitor and why?
Hevasure’s intelligent monitoring technology measures a range of parameters; all important indicators of closed circuit system condition:
Q Dissolved oxygen: Dissolved oxygen is the main driver of corrosion. By measuring DO we can identify whether the system is air-tight and check how quickly base-levels are returned to following the introduction of fresh aerated water.
Q Pressure: A closed system must maintain a positive relative pressure at all times to avoid air being sucked into the system. We monitor pressure continuously to check if pressurisation units and expansion vessels are correctly set-up and maintained.
water treatment of closed-circuit systems (BG 50) citing it as best-practice. BG 50:2021, Water Treatment for Closed Heating and Cooling Systems, was published in November last year, including new recommendations in relation to remote water system monitoring.
In section 2.10 Real-time monitoring of system parameters, BG 50 says: “Analysis of system water quality provides useful information about the concentration and performance of corrosion inhibitors and biocides but only gives a partial picture of the overall condition of the system and the extent to which corrosion is taking place. Furthermore, corrosion coupons without electric monitoring do not show sudden changes in corrosion conditions that can be linked to specific events and actions.”
The guide then goes on to recommend monitoring and interpreting selected system parameters in real-time to provide advance warning and diagnosis of problems, with information sent electronically to the maintenance team, thereby facilitating remedial investigation and action.
Sampling shift
While periodic water sampling is still required, BG 50:2021 states that where real-time monitoring is employed, the frequency of this process may be reduced. The guide also suggests that monitoring can be used to plot trends, providing an early alert to changes in the system.
This is a big shift since the last version of the guide in 2013, showing how far the water treatment industry and the technology available to it has come. In the past, sampling and
corrosion coupons were the mainstay of water treatment processes, often leading to system flushing, which as mentioned, wastes water and energy.
Furthermore, sampling is not an instantaneous approach – the water is sent to a laboratory, analysed and then sent back, potentially taking weeks, by which point conditions might have changed.
Not only does this miss things, inappropriate intervention can exacerbate issues and make problems even worse. Unlike sampling, real-time monitoring of multiple parameters helps identify the root cause of water quality changes, directing teams to apply an appropriate and timely solution
Overall, the collation and interpretation of data throughout a HVAC system’s life will lead to more efficient maintenance practices, which save time, money and energy. This approach also means that whole life costings can be more accurately predicted and achieved, helping specifiers confidently create long-lasting, energy efficient, HVAC schemes with more precise budgetary control.
By monitoring our buildings, we can adjust and improve how they operate, enhancing commercial spaces while gaining knowledge that can lead to future developments. There is no need for a ‘finger in the air’ approach anymore. A real- time, continuous picture of system condition will prevent breakdown, enhance the life of critical (and expensive) plant, and save energy across the board.
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Q pH: For systems containing aluminium the pH must not exceed 8.5; the point at which passive films could break down and aluminium com- ponents, such as heat exchangers, can start to corrode. Changes in pH also indicate potential problems with the water chemistry and biology.
Q Galvanic currents: Our patented galvanic current sensor allows us to determine the rate of corrosion of steel (expressed in mm per year). In uninhibited systems galvanic currents increase in proportion to DO and temperature. However, inhibitors, when at the correct dosing level, passivate metal surfaces, suppressing corrosion and galvanic currents. This provides us with an easy way to determine if inhibi- tors are behaving effectively under operating conditions.
Q Crevice corrosion: Crevice corrosion is a par- ticularly insidious form of corrosion leading to rapid pitting attack and pin-holing. It occurs in localised regions such as weld seams and under debris where a micro-environment can be formed. Our unique and patented sensor provides early indication of crevice corrosion
Q Leaks (water make-up volume): By measuring water make-up volume, leaks in the system can be identified and planned flushing activities can be monitored.
Q Temperature: We measure temperature to en- sure that the system is operating as intended.
Q Inhibitor/glycol concentration: Under-dosing with chemicals can adversely affect corrosion and performance. Conversely, over-dosing wastes money and is bad for the environment. By measuring conductivity, we can advise whether the concentration of water treatment products is within recommended levels.
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