The Importance of Closed-System Maintenance to Achieve High Water Quality

The importance of closed-system maintenance and related water quality has become a significant issue in buildings in recent years due to the rise in energy-efficient designs and the use of leaner materials compared to traditional iron and heavier metals.

All buildings benefit from closed-system treatment where present, but thin-walled carbon steel pipes and low-velocity, energy-saving designs mean water quality control is more critical than ever before.

Background

Heating and cooling systems in buildings are not only essential for the comfort of employees but are also often critical to the smooth operation of the business itself.

In closed heating and cooling systems, water treatment comprises a number of techniques, including:

? Pre-treatment of fill water

? Removal of dissolved gases

? Chemical water treatment

? pH management

? Solids removal and filtration

? Galvanic anode cathodic protection/electrochemistry

? Bacteria and biofouling inhibition by biocides

Published standards

Water treatment is essential for the avoidance of biological fouling (biofouling), corrosion and scale. There are published standards for water quality in closed systems at all stages of use.

BG 29/2021 and BG 50/2021 are the BSRIA guides that combine the latest advice on pre-commission cleaning, an essential process that helps water systems perform at their optimum level. They provide an introduction to current theory and practice of water treatment in closed building systems. They are intended for use by design engineers, installing contractors and the maintenance staff responsible for looking after the completed systems. In particular, they help facilities managers and others choose the most appropriate water treatment for their systems.

The treatment of water in modern closed heating and cooling systems is essential for the avoidance of microbiological fouling (biofouling), corrosion and scale. These problems can result in energy wastage, poor system performance, and the need for early replacement of plant and components. Many facilities managers have minimal understanding of how water treatment works and what it is intended to achieve, and the consequences of ineffective water treatment can sometimes be disastrous.

BS 8552:2012 gives recommendations for the design of the sampling programme during each phase of the system lifecycle, including the location and suitability of sampling points and frequency of sampling and recordkeeping, to facilitate the control of closed system water quality throughout the life of the building. It also gives guidance on procedures for the collection, preservation, handling and storage of samples prior to analysis and the selection of the analytical parameters appropriate to the sampled system and life stage.

Why monitor closed-system water quality?

Monitoring closed-system water quality is essential for several compelling reasons, particularly in environments where water systems are integral to the operation and safety of facilities.

Closed systems, such as those found in heating, cooling, and industrial processes, rely on a controlled environment where water does not regularly enter or exit the system except in controlled conditions.

There are several key reasons why monitoring the water quality in these systems is critical:

1. Preventing corrosion, scale formation and oxygen ingress

Corrosion: If water quality is not adequately maintained, corrosion can occur, weakening metal components and leading to leaks, failures, and potentially catastrophic system breakdowns. The build-up of oxygen in water is the most significant concern, as it allows corrosion to form.

Oxygen ingress: Oxygen is introduced into a closed system when filled or topped up. Leaks or incorrect system pressures can influence this. Low pressure draws air in through seals, whereas high pressure draws in fresh water when the system heats up and expands. Oxygen ingress to a closed system is the single most significant contributing factor to corrosion problems.

Scale formation: Poor water quality can lead to the formation of scale (mineral deposits), which can clog pipes, reduce system efficiency, and increase energy consumption due to reduced heat transfer efficiency. Approximately 1mm of scale in a domestic water heater can equate to a 10% loss of heat transfer.

2. Extending equipment lifespan

Regular monitoring and maintenance of water quality help extend the life of system components. The risk of premature system degradation decreases significantly by controlling parameters like pH, conductivity, and dissolved solids. This maintenance is far less costly than replacing equipment due to neglect.

3. Ensuring system efficiency

A well-maintained water system operates at peak efficiency. Scale, biological fouling, and corrosion can cause systems to work harder, consuming more energy and increasing operational costs. Monitoring helps maintain the balance needed to ensure systems are not overworked, thus conserving energy and reducing costs.

4. Maintaining heat transfer efficiency

Heat transfer efficiency is critical to operational effectiveness in systems like cooling towers and boilers. Water quality issues such as scaling and biological fouling can drastically affect the system’s ability to transfer heat, leading to inefficiencies and increased energy usage.

5. Preventing microbial growth

If not correctly maintained, closed systems can become breeding grounds for microorganisms, including harmful bacteria.

The presence of unwanted bacteria in closed heating and chilled systems can cause several potentially serious problems, including:

? Accelerated system corrosion

? System blockages

? Reduced system efficiency

Pseudomonas, sulphate-reducing bacteria (SRBs), nitrite-reducing bacteria (NRBs), and other bacteria can contaminate closed heating and chilled water systems if a correct water treatment regime is not correctly applied.

Regular water quality monitoring helps identify system changes and control the growth of such microbes, thus reducing the risks associated with microbial contamination.

6. Compliance with regulations

All industries are subject to environmental and safety regulations that require regular monitoring of closed water systems. Compliance avoids legal and financial penalties and ensures that the facility adheres to best practices for environmental stewardship and worker safety.

7. Quality assurance

In industries such as pharmaceuticals, food and beverage, and electronics manufacturing, water quality directly impacts the quality of the final product. Impurities in water can compromise product quality, leading to potential safety issues and economic losses due to product recalls or non-compliance with industry standards.

8. Early detection and problem-solving

Monitoring allows for the early detection of potential problems, such as leaks in the system, impaired flows, and heat transfer, not to mention blocked and inoperative control valves, before they become severe. Facilities can avoid unexpected downtime and expensive emergency repairs by identifying and addressing issues early.

What are your obligations?

The current British standard BS 8552: 2012 Sampling and Monitoring of Water from Building Services Closed Systems states that closed-circuit heating and chilled systems should be sampled and tested every quarter. Understanding the guidance is important to ensure the correct application of it to each system.

Closed-system testing and analysis should be under the guidelines outlined in BSRIA Closed Heating and Cooling System BG 50/2015 (2021), as highlighted in Chapter 6.4: Management of the Water Treatment Program.

Risks of not monitoring

Untreated closed systems could be a breeding ground for Pseudomonas, nitrate and sulphate-reducing bacteria. Heating systems can become heavily scaled or corroded, and chilled systems can become full of Pseudomonas slime-forming bacteria.

Even though there is no actual risk of Legionella within these systems, fouling and non-existent or poor treatment regimens can still cause many difficulties and potentially result in unnecessary costs to those maintaining them.

The benefits of monitoring

? To protect from damage – avoidable poor water quality can damage systems beyond repair

? To maintain performance – use up to 10% less energy than poorly maintained systems

? To protect you from exposure to the risk of litigation in the event of failure by avoiding breach of warranty and incorrect commissioning

Questions you should ask yourself

? How much would it cost to replace the heating or cooling system?

? What disruption and associated problems would this cause?

? How much is your energy bill?

? How significant is your organisation’s carbon footprint?

All these are essential considerations for any business with a heating or cooling system.

Litigation costs for closed-system problems against warranty, system commissioning and handover can range from tens to hundreds of millions of pounds annually. Even successfully defending your case is expensive. Working to industry standards with independent expert advice is the best way to avoid litigation surrounding water quality and keep systems in peak condition and in compliance with industry standards.

Conclusion

In conclusion, monitoring closed-system water quality is an indispensable practice that supports operational efficiency, ensures regulatory compliance, protects equipment, and safeguards health. Proactive water quality management is critical to reflecting a commitment to sustainability, safety, and efficiency.

“Minimise risk, deliver compliance, make it simple”

At Rock Compliance, we are passionate about helping our clients achieve compliance in line with our core promise. To achieve this, we offer a wide range of services, suitable across the sectors.

For more information on monitoring closed-system water quality or any of the compliance solutions available from Rock Compliance, please contact Andy Smith on:

T: 07983 179426

E: [email protected]