Filter Replacements in Southampton Gym: Case Study

When a gas-fired heater hasn't had its intake filters changed in years (decades?), the problem isn't just dust — it's air quality, system efficiency, and potentially fire compartmentation too.

Here's how ARM Environments' filter replacement service helped a Southampton gym get its heating system back on track, and what the works uncovered along the way.

The brief

Following an initial enquiry to check the fire dampers on site, we spotted a much more important problem: an old, neglected, and misunderstood heating system with dust-blocked intake filters connected to the main hall. ARM Environments proposed supplying and fitting new filters suitable for the space, timed to coincide with the facility's summer shutdown when flooring in the hall was already being lifted for other works.

The scope was tightly defined: attend the site, remove the intake grille, remove the old filters, vacuum the intake plenum and dampers as far as accessible, fit seven new replacement filters, and refit the grille. Cleaning of the wider ductwork and supply grilles sat outside this scope.

What we found at the Southampton Gym

When our engineer opened up the intake in August, the existing filters were very heavily contaminated, with no record of when they had last been changed. The volume control damper behind them showed moderate to heavy contamination too — consistent with the system having run unfiltered, or with collapsed filters, for a considerable period. One vertical support within the filter housing was also found loose.

This is a common find in older gas-fired heater and air handling unit (AHU) intakes: filters degrade in the background, and unless someone is physically checking them, contamination builds year after year with no visible warning.

The remediations: filters and a clean

Our team removed the old filters, vacuumed the intake plenum and damper as far as accessible, and fitted seven new filters before refitting the grille. Photographic evidence taken before, during, and after the works showed a clear before-and-after: heavily soiled dampers and plenum surfaces were left visibly clean, and the new filters showed no sign of the contamination present on the originals. 

Practical recommendations for the gym

ARM also advised on the future maintenance of the system:

• Improve access. The filters had been difficult to reach because flooring covered the intake grille. ARM suggested cutting a permanent, removable section of flooring — roughly 70mm — directly in front of the grille, so future filter changes don't require lifting large sections of floor each time.
• Filter check frequency. Given the heater only runs during occupied winter months, ARM suggested filters be assessed visually at the time of the annual gas heater service, rather than committing to a fixed replacement schedule regardless of actual condition.
• System operation. The plantroom's summer/winter switch appears to run the fan only (not the heater) in summer mode. Notably, because the intake draws air from within the Main Hall itself, the system recirculates internal air only and does not introduce outdoor air — a detail worth factoring into any wider indoor air quality planning for the space.

Why this filter service matters

Neglected filters on a gas-fired heater intake don't just mean dustier air, they restrict airflow, can strain the heater's fan and burner, and, over years of neglect, allow debris to build up in ductwork and plenums downstream. For sports facilities, where occupants are engaged in physical activity and air exchange rates matter, keeping filtration on a proper maintenance cycle is a straightforward, cost-effective way to protect both system performance and occupant health.

Regular filter checks and replacements, backed by a Smart Filtration approach, help catch this kind of degradation before it reaches the point of "very heavily contaminated" — and before it starts affecting the wider system, as the deteriorated fire blocks and dirty dampers found here demonstrate.

Get in Touch

If your building's heating or ventilation intake hasn't had its filters checked recently, ARM Environments can help — from straightforward filter replacements through to full AHU condition reporting. Get in touch with the team, or find out more about our filter replacement service.