When an HVAC coil begins to leak or fails outright, replacement is usually the only practical solution. HVAC coil replacement in a commercial building involves a site survey to assess the failed unit, bespoke manufacture of a new coil matched to the existing air handling unit (AHU), and careful installation to restore system performance with minimum disruption.
SPC has been manufacturing and supplying replacement coils from Leicester for over 50 years, supporting building owners, facilities managers, and mechanical contractors through the process from first inspection to delivery.
Why Do HVAC Coils Fail?
Freeze damage is one cause of coil failure, but it is far from the only one. In commercial buildings, coils fail for a range of reasons, and understanding the cause matters — both for specifying the right replacement and for avoiding a repeat failure.
Common causes include:
- Corrosion over time, particularly in coastal or industrial environments where airborne contaminants attack copper tubes and aluminium fins
- Mechanical wear at joints and connections, which leads to gradual leaks that worsen under system pressure
- Age and material fatigue — coils have a finite service life, and units installed 15 or more years ago can simply reach the end of theirs
- Poor water quality, where untreated or poorly balanced system water accelerates internal corrosion
- Physical damage during maintenance or from debris in the airstream
A leaking coil will reduce heat transfer efficiency, risk water damage to surrounding plant and structure, and ultimately cause system downtime. The earlier a failing coil is identified and assessed, the simpler and less disruptive the replacement process tends to be.
What Does HVAC Coil Replacement Involve?
Replacing a coil in an active commercial building is not a straightforward swap from a catalogue. AHU casings vary significantly by manufacturer, age, and specification, which means a replacement coil must be engineered to fit the existing housing precisely. Getting this wrong creates air bypass around the coil, reduces efficiency, and can impose additional strain on pipework.
The replacement process typically follows four stages.
Site survey. An area sales manager or the technical team visits to inspect the failed coil, assess the condition of the surrounding system, identify any contributing factors to the failure, and take the precise measurements needed for manufacture. This is particularly important when the coil cannot be removed easily, or when the original manufacturer’s records are no longer available.
Specification and design. Using the survey data, a replacement coil is designed to match the original dimensions, row configuration, fin pitch, and pipework connections. Material selection is confirmed at this stage, including whether standard copper-and-aluminium construction is appropriate or whether enhanced corrosion protection is needed for the application.
Manufacture. The replacement coil is built to order. SPC manufactures coils at its Leicester facility, and each unit is pressure tested to 22 bar before despatch, in line with ISO 9001:2015 quality procedures.
Installation. Because the replacement coil has been manufactured to match the existing AHU housing precisely, on-site modifications are minimised, reducing installation time and disruption to the building.
Why Bespoke Manufacture Matters
An HVAC coil that fits incorrectly will never perform correctly. Even small dimensional variations can create air bypass channels that reduce effective heat transfer, meaning the new coil underperforms from day one. A bespoke approach eliminates this risk.
SPC manufactures replacement coils for AHUs from any manufacturer, not only those originally supplied by SPC. All that is required are the survey measurements and the application data, water temperatures, airflow rates, and required thermal output, to produce a coil that integrates correctly with the existing plant and meets the system’s performance requirements.
SPC's Replacement Coil Service
SPC’s Area Sales Managers carry out site surveys across the UK, working alongside facilities teams and mechanical contractors to scope replacement coil projects. Recent surveys have included commercial retail environments, where failed coils have affected heating and cooling across large public-facing buildings.
The full range of coil types SPC manufactures for replacement projects includes water coils (heating and cooling), steam coils, DX refrigerant coils, runaround coils, and electric heater batteries.
For building services professionals seeking to understand coil selection and heat transfer principles in more depth, SPC offers a CIBSE-approved CPD session, An Introduction to Coil Heat Exchangers, available free of charge to architects, mechanical consultants, and contractors.
For guidance on planned preventive maintenance schedules for air handling units and associated heat exchangers, CIBSE Guide B provides a recognised industry reference for building services engineers.
Frequently Asked Questions
Service life depends on the application, water quality, and maintenance regime, but many coils in commercial AHUs last between 15 and 25 years. Coils in coastal, industrial, or high-humidity environments may degrade faster due to increased corrosion exposure.
Yes. SPC manufactures replacement coils for AHUs from any manufacturer. The site survey process captures all the information needed to produce a correctly specified replacement, regardless of who made the original.
For most commercial replacements, a site survey is strongly recommended. It ensures the replacement coil is manufactured to the correct dimensions and specification, reducing the risk of installation problems and the cost of re-work.
Lead times depend on the coil type and complexity. Where a failure has caused urgent downtime, SPC’s team can advise on the fastest available route. Contact the team to discuss your timeline.
Contact SPC for Coil Replacement Support
If an HVAC coil is leaking or has failed, SPC’s team can help with a site survey and bespoke replacement.