An island-wide hospital renovation in Sri Lanka specified 80 fan coil units (FCU) fitted with H13 HEPA filtration for operating theatres and critical wards, the order confirmed in early February 2026.
Healthcare ventilation is governed by air-cleanliness classes rather than comfort alone, and the operating theatre is the strictest case: a space that drifts below its required air changes per hour quietly raises infection risk without anyone noticing until a cluster appears. Placing HEPA filtration at the terminal fan coil, rather than relying only on central plant, gives localised and auditable protection exactly where surgery happens. The engineering subtlety is that the filter is also a resistance, so the fan must be re-selected to hold design airflow as the media loads, not just on a clean filter on day one.
Why HEPA at the FCU Level
In healthcare spaces, the cleanliness class of the air decides infection risk. Operating theatres typically demand ISO Class 5-equivalent air, achieved by passing supply air through H13 or H14 filters that capture 99.95% of particles at the MPPS (most penetrating particle size) of 0.3 µm. Placing HEPA at the terminal FCU gives localised, auditable filtration exactly where it matters, rather than relying only on central plant.
The challenge is integration: an FCU is a cooling and air-movement device, while HEPA is a resistance element. Adding the filter changes the pressure drop, so the fan must be selected to deliver design airflow against the higher total resistance without sacrificing cooling capacity. If the fan is not re-selected, the unit will deliver fewer air changes than the theatre requires.
There is also a commissioning dimension. A clean-filter pressure drop differs from a loaded one, so the system must be verified at both states to confirm the air-change rate holds through the filter's service life, not just on day one.
FCU and Filter Configuration
The specified units pair a standard fan coil chassis with a terminal HEPA stage sized for the theatre air-change rate. Typical parameters are listed below.
| Parameter | Typical value | Note |
|---|---|---|
| Filter class | H13 HEPA | 99.95% at 0.3 µm |
| Air changes | 20–25 ACH | Theatre requirement |
| Coil capacity | 3–8 kW cooling | Per room load |
| Fan pressure | +80 Pa with filter | Re-selected for HEPA |
Filter loading is a lifecycle issue: as the HEPA clogs, pressure drop rises and airflow falls unless the fan has headroom. Specifying with that margin protects the air-change rate over the filter's service life and avoids a slow drift into non-compliance between scheduled changes.
The cooling coil must also handle the room's latent and sensible load at the delivered airflow, so the FCU selection balances filtration resistance against thermal duty rather than treating them separately.
Checklist for Healthcare FCU Selection
Engineering teams can apply these points when specifying clinical fan coil units:
- Confirm the class: Match H13/H14 to the space's required cleanliness, not a generic "HEPA" tag that may not meet the standard.
- Re-select the fan: Add filter pressure drop to the duty point before choosing the unit, so airflow holds as the filter loads.
- Plan access: Filters must be changed without contaminating the clean side, so specify a proper housing and change procedure.
- Validate airflow: Commission to measured air changes, not nameplate assumption, and re-test after filter replacement.
- Spares plan: Stock replacement H13 cassettes for uninterrupted operation and to avoid emergency substitutions.
- Document compliance: Keep filter certificates and commissioning reports for the healthcare authority's review.
Significance for the Project
Keruite manufactures fan coil units alongside its broader HVAC lines at the 80,000 m² Dezhou facility, and the H13 specification shows how standard products adapt to clinical duty. With 30+ years of manufacturing and ISO 9001:2015 certification, the supply supports a healthcare programme where filtration performance is non-negotiable.
For hospital engineers, the lesson is to select the FCU for the loaded condition, not the clean-filter condition, and to verify air changes on site. the company supports the selection with in-house testing so the quoted performance is defensible during inspection.
For clinical engineering teams, commissioning to measured air changes, not nameplate assumption, is the step that separates a compliant theatre from a marginal one, and the filter certificate plus commissioning report should be filed for the healthcare authority's review. Stocking replacement H13 cassettes avoids emergency substitutions that could break the filtration chain during a change-out. With 30+ years of manufacturing and ISO 9001:2015 certification at the 80,000 m² Dezhou facility, the company can support a healthcare programme where filtration performance is non-negotiable and must be defensible during inspection.
Terminal HEPA filtration also simplifies the infection-control argument during design review, because the cleanliness class can be demonstrated at the point of delivery rather than inferred from central plant alone, and the commissioning report becomes a defensible record for the healthcare authority. For wards and isolation rooms beyond the theatre, the same logic applies: matching H13 or H14 to the space's required class, and re-selecting the fan for the loaded filter, prevents the slow drift into non-compliance that occurs when pressure drop rises between scheduled changes. Stocking the correct cassettes then keeps that protection uninterrupted through the filter's service life.
Engineers in Dezhou respond to selection enquiries within 24 hours, and the factory ships most standard fans from its 80,000 m² site within agreed lead times.