FCU Plenums — Made to Fit Your Fan Coil Units Exactly
Every fan coil unit needs plenums — the boxes connecting the unit's inlet and discharge to the ductwork and grilles around it. Spigot positions, sizes and handing vary between manufacturers and even floors, so stock plenums rarely fit without compromise. We fabricate FCU plenum boxes to order in galvanised steel: your dimensions, your spigot layout, your connection type. Design supply and return plenums in our 3D plenum builder — with starting presets for Daikin, Mitsubishi Electric, Samsung and more — and send the design straight to us for a quote.
The plenums that make an FCU installation work
- Discharge plenums with single or multiple spigots for flexible or rigid duct
- Return air / inlet plenums with grille connections
- Grille and diffuser boxes for supply and extract terminals
- Transition pieces between FCU spigots and distribution ductwork
Why made-to-order beats adapting stock boxes
Adapting a stock plenum on site — blanking spigots, cutting new holes, packing gaps — takes time and leaves leaks. A box made to the unit's actual dimensions drops straight in and seals properly. For the ductwork either side of the plenum, see our FCU ductwork page — we supply the whole package from one workshop.
From single boxes to full fit-out schedules
Design your plenum in the 3D builder, configure a standard grille box online, or send us your FCU schedule and we'll price the full set — matched, labelled and delivered to suit your installation sequence.
Frequently asked questions
Can you make plenums for any fan coil unit manufacturer?
Yes — we work from your unit's dimensions and spigot layout, not from a fixed catalogue, so any manufacturer and model can be accommodated. Send the unit datasheet or a simple sketch with sizes and we'll fabricate to suit.
What information do you need to price an FCU plenum?
Box dimensions, spigot sizes, positions and quantities, and the connection type (spigot for flexible duct, Mez flange, or raw edge). For full schedules, the FCU model list with quantities per type is ideal.
Are your FCU plenums sealed and ready to install?
Yes — fabricated in galvanised steel with sealed seams and protected edges, ready to fix to the unit and connect. Insulation and acoustic lining requirements can be discussed per project.
How quickly can you deliver plenum boxes?
Because we fabricate in-house, made-to-order boxes typically despatch within days rather than weeks — useful when a fit-out programme discovers it needs boxes the stockists don't hold. Contact us with your dates and we'll confirm.