This page sets out the technical specification of Flat Duct for Underfloor Air Distribution / Underfloor Supply Flat Duct as supplied by GUANDE, together with the selection rules that determine which variant suits a given project. It is written for specifiers, estimators and contractors who need to confirm a size, a material build-up and a connection method without waiting on a quotation.
| Item | Specification |
|---|---|
| Material / Construction | 130×30 mm |
A flat duct for underfloor air distribution. Its shallow 130 x 30 mm section is deliberately chosen so the duct can sit inside the floor build-up without raising the finished floor level. Air is delivered to low-level supply terminals, which suits underfloor air distribution (UFAD) strategies in residential and light commercial spaces.
A distribution box is a pressure-loss component and its contribution should be counted in the system calculation. Loss increases with the number of active ports and with any reduction in internal cross-section, and it is affected by how the incoming air is presented to the box. Units that accept a larger inlet spigot and split the flow internally perform noticeably better than units that simply have a common chamber. When a system is marginally short of air, the box is frequently the component that was left out of the calculation.
Distribution boxes are usually the largest single component in a residential ventilation system, which makes their mounting position a design decision rather than an installation detail. The box must be accessible enough to inspect and to re-connect a branch if required, but it should be located where its size does not compete with other services. Mounting it directly above a habitable room without acoustic consideration is a common cause of transmitted noise. A box located in a riser or corridor void is almost always the better choice.
Because the box is a high-surface-area component located in a cold void, it is a natural condensation risk in the same way a duct run is. Extract-side boxes handle warm moist air and are the higher risk of the two. An insulated box, or an insulated jacket applied on site, is the correct specification wherever the assembly sits outside the thermal envelope. Omitting this detail to save cost is a decision that typically reveals itself as staining on a ceiling within the first heating season.
Quality inspection at GUANDE is not a final gate — it runs through the whole process. Incoming raw material is checked against specification before it enters production. In-process checks monitor dimensions and surface finish at defined intervals during the run. Finished Flat Duct for Underfloor Air Distribution / Underfloor Supply Flat Duct are inspected against the approved sample, and a batch record is kept against every shipment so that any issue can be traced back to its production parameters.
Our plant runs scheduled production for Flat Duct for Underfloor Air Distribution / Underfloor Supply Flat Duct with typical lead times of 15 to 25 days for standard items and 25 to 40 days for custom tooling projects. We load mixed containers directly at the factory, which lets us combine several product lines from your ventilation schedule into one shipment and reduce freight cost per unit. Confirmed lead times are stated on the order acknowledgement, not estimated at enquiry.
Use the following rules when converting a project drawing into an order. They reflect how the product performs in ceiling voids, plant rooms and riser cupboards, where the practical limits are usually set by branch count, port configuration and pressure loss rather than by the headline dimension.
Size the run from the design air flow and the acceptable pressure drop, not from the fan spigot. Undersizing a distribution boxes run is the most common specification error and it cannot be corrected later without re-opening the ceiling.
Where the run passes through an unconditioned space, condensation risk — not mechanical strength — normally decides the specification. In those locations the insulated variant is the correct default and a bare equivalent is a false economy.
Keep one connector family for the whole run. Every change of system introduces an adapter, and every adapter is an additional leak path and pressure loss point.
Complete the layout with our floor supply air outlet assembly, ABS distribution box, linear floor supply grille and TT flat duct.
GUANDE manufactures Flat Duct for Underfloor Air Distribution / Underfloor Supply Flat Duct at our factory in Dezhou, Shandong, China, and ships direct to HVAC contractors, distributors and project specifiers worldwide. Wholesale, OEM and ODM programmes are welcome. Items are supplied in export cartons with the size and quantity marked on the outer label. For OEM programmes we can apply your own artwork and labelling subject to a minimum order quantity.
The products below are routinely specified alongside the item discussed in this guide. GUANDE manufactures the full range in our own plant for consolidated shipping:
Q: What height does the duct require?
A: The section is 130 x 30 mm, so a shallow floor build-up is enough.
Q: Can it be used with a raised floor?
A: Yes, it suits raised-floor and screed-embedded supply layouts.
Q: Which terminals match it?
A: See our floor supply outlet assembly and linear floor supply grille.
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