HVP Magazine – Guardian looks at some of the problems that cause poor commercial HVAC performance
Toby Hunt, Managing Director at Guardian Water Treatment, looks at some of the issues that lead to poor performance in commercial HVAC systems and explains how to mitigate these risks.
Commercial HVAC systems are complex structures compared to their domestic counterparts. They have to work on a much larger scale to meet demand in, for example, multi-tenant office buildings or industrial warehouses. In critical infrastructure, such as hospitals or data centers, heating and cooling systems must remain operational at all times – downtime is simply not an option.
Closed circuit water systems play a vital role in commercial heating and cooling. If corrosion can occur within these systems, it can be very difficult and expensive to correct. Operational inefficiencies or failures can cause serious damage to expensive assets, with repair costs and downtime running into the millions.
What can go wrong?
As the name suggests, closed circuit systems are closed units containing a fixed volume of recirculating water. Theoretically, this water should not be exposed to anything outside of the pipework. However, poor maintenance or heavy-handed water treatment can lead to oxygen ingress, which creates the ideal conditions for bacteria to grow.
Oxygen ingress is the precursor to all corrosion in closed circuit water systems, but the industry’s traditional method of monitoring the condition does not detect oxygen levels. Instead, water samples and corrosion coupons target bacteria and dissolved metals, but by the time these are detectable, the damage is already done. Bacteria are most destructive during the sessile phase, as a localized biofilm accumulates on the tube wall or colonizes around pockets created by corrosion debris.
This bacterial slime can restrict water flow, contribute to reduced thermal efficiency and facilitate the growth of dangerous waterborne pathogens, such as legionella and pseudomonas. Once bacteria can flow freely and are therefore picked up by lab samples, their presence is simply an indicator of existing problems.
Prevention is better than cure
Without accurate data to hand, standard treatment usually consists of flushing and dosing chemicals. While this can be effective against bacteria, in many cases it fails to identify and correct the cause, leading to repeated problems and further corrosion of pipes and components.
A much more effective approach is to go back a step further and address the root cause of corrosion. If oxygen can be detected before bacteria have had a chance to thrive, interventions can be preventive rather than reactive, environmental impact can be minimized and, most importantly, systems will perform better with less risk of failure.
Unlike other areas of construction, the water treatment industry has stuck to its traditional maintenance and monitoring methods for too long. Technological innovations in recent years have brought water monitoring in line with other areas of building management, eliminating the need to wait days or weeks for sample results to return from the lab.
The latest remote monitoring technology protects critical HVAC systems by continuously monitoring a range of parameters that cause corrosion in closed circuit water systems, including oxygen, pH and inhibitor levels, as well as pressure and corrosion rates.
Measurements are taken every 15 minutes, 24 hours a day and live data is delivered directly to facility managers or maintenance teams, with immediate alerts if critical levels are exceeded. With this vital information at hand, water hygiene is improved, pipes protected and maintenance regimes can be better informed.
Chemical requirements are not eliminated, but use can be adapted and reduced, rather than unknowingly as a precaution.
It’s never too late
Remote monitoring technology has revolutionized the industry to the extent that its approach is now recommended in BSRIA’s BG50 best practice guidelines for pre-deployment cleaning. The benefits do not end with delivery.
Real-time monitoring can be used throughout the lifetime of a commercial water system, or as a one-time ‘health check’ over a period of time to identify the root cause of a problem. In which phase remote monitoring is applied, the result is always a targeted, effective and above all preventive water treatment.
From consulting, construction and cleaning before commissioning to completion and beyond, accurate monitoring and preventive maintenance play a key role throughout the life of a commercial HVAC system, mitigating risk and ensuring that buildings (and the people who use them) stay healthy, efficient and operational