RETROFIT IN HVAC
Retrofit policies for boiler systems: ensuring water quality and efficient heating
Steve Simmonds, Spirotech’s special projects engineer, highlights the importance of keeping heating and air conditioning systems in commercial buildings, office blocks, and apartments functioning reliably
K
eeping buildings in a good state of repair and ensuring all services are working efficiently is the challenge facing all facilities managers.
However, when times are difficult economically, tough decisions need to be taken on how to spend the available budget. As systems age, maintenance demands increase, making reliability harder to achieve. At some point, the cost and frequency of repairs
become unsustainable, signalling the need for a full system replacement. As components wear out and maintenance expenses rise, facilities managers must determine when retrofitting parts is still viable and when a complete overhaul is necessary. While retrofitting components in relatively new
systems is a normal part of ongoing maintenance, persistent reliability issues and frequent emergency repairs suggest that replacement may be the better option. That said, strategic retrofitting can enhance efficiency, reduce fuel consumption, lower operational costs, and minimise downtime. However, prior to undertaking a major refit, it is vital to carry out a review of the original baseline specification information and compare it with the actual set-up and installation in place.
The importance of water quality in boiler systems
Water quality is often overlooked, yet it plays a crucial role in maintaining an optimised heating system. Poor water quality can lead to scaling, corrosion, and sludge buildup, all of which reduce efficiency and shorten the system’s lifespan. Key factors affecting water quality include high
mineral content, which causes scale deposits on heat exchangers and piping, reducing heat transfer efficiency and increasing energy consumption. Implementing a water treatment plan as part of
a retrofit policy can improve system performance, extend equipment life, and lower operational costs. A poorly selected-installed or maintained
pressurisation unit and expansion vessel will result in negative pressures around the systems, causing air to be drawn in through automatic air vents, gaskets and via micro-leaks. If air continually gets into the system, corrosion
will occur resulting in a build-up of magnetite and hematite, leading to component failure. Whilst corrosion inhibitors play a part in maintaining the integrity of LTHW and CHW systems, they do not impact on the content of inert gases such as nitrogen and carbon dioxide that are present in large volumes. These inert gases play a big part in reducing the system’s overall efficiency. Therefore, degassing the system water is fundamental to ensuring good water quality. Under-sizing an expansion vessel will over
pressurise the system, which can lead to a problematic system, in which the system may need
Left: Steve Simmonds, Spirotech’s special projects engineer
www.heatingandventilating.net
refilling regularly - this increases the form of scale. Unfortunately, the newly introduced water will be oxygen-rich and further deplete any corrosion inhibitors in the system.
The growing need for maintenance and retrofitting
An ageing boiler system will inevitably have increasingly complex maintenance requirements and more frequent attention. Certain factors impact on the decision as to when it is time to move from a retrofit policy to a replacement one. These include rising costs due to declining efficiency, frequent breakdowns and emergency repairs and increasing downtime impacting on productivity. Facilities managers eventually must weigh up when it is time to move from a retrofit policy to a replacement one. This will depend on a variety of factors including the age of the boiler. Boilers that have been in place for more than 20 years may not be suitable from an economic viewpoint for retrofitting. A judgement needs to be made on the cost of repairs and retrofits, or whether a replacement is the solution. If a retrofit can bring meaningful operational efficiency gains of between 10 and 20% or more, that may be enough to go-ahead with the work. However, if improvements are minimal, replacing the system is the better option. Additional considerations include regulatory
compliance and the availability of spare parts. As older systems become obsolete, finding replacement components can be difficult and expensive, making retrofitting less practical. Building management involves balancing
multiple operational concerns. Given the critical role of heating systems in occupant comfort, ensuring reliability is paramount. Excessive downtime that disrupts businesses or building operations may necessitate replacing old boilers with modern, efficient alternatives. When installing a new boiler or complete heating system, it is essential to select one that meets the building’s performance requirements. Consulting with technical experts during the design and installation process can aid in making informed choices. Post-installation, maintaining high water quality is crucial for ensuring long- term system efficiency and reliability.
20 June 2025
DOWNLOAD THE HVR APP NOW
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36
