A custom metal underfloor air distribution box with multiple flat duct outlets. Dimensions are made to order and the round top inlet is compatible with standard circular ducts while the side outlets match underfloor flat ventilation pipes. Casing material can be galvanised steel, aluminised zinc steel or stainless steel.
In ceiling voids, plant rooms and riser cupboards, distribution boxes is rarely the whole system — it is one link in a chain. Getting it wrong shows up later as unbalanced branch flows, pressure drop at junctions and space constraints. The selection criteria that actually drive performance are branch count, port configuration and pressure loss, and those are the three things a buyer should confirm before placing an order.
A radial system runs an individual duct from the distribution box to each terminal, which means every branch can be sized precisely for its own flow and adjusted without affecting the others. A trunk-and-branch system shares a common run and branches off it, which uses less material but makes balancing considerably harder. For residential MVHR the radial approach has become the default because the additional duct cost is small, the pressure loss is lower, and commissioning is dramatically simpler. The distribution box is the component that makes this possible.
The number and arrangement of ports on a distribution box should follow the building layout, not the other way round. A box with eight ports arranged evenly around its circumference suits a central plant position with branches radiating outwards. A box with ports grouped on two faces suits a unit mounted against a wall. Getting this wrong means that half the branches have to double back on themselves, which adds length, pressure loss and cost. Port configuration is the specification decision that most affects the total length of duct in the system.
Every Custom Underfloor Air Distribution Box, Metal HVAC Air Plenum Box with Multiple Duct Interfaces for Fresh Air Ventilation System we ship is produced on our own production line in Dezhou, Shandong, China. Because we control the tooling and the forming equipment directly, we can guarantee that the product you receive in container three is dimensionally identical to the sample you approved in the first order. That consistency is difficult to achieve when production is outsourced, and it is the single most common complaint we hear from buyers who have tried sourcing this category through intermediaries.
Our mould shop supports custom development for Custom Underfloor Air Distribution Box, Metal HVAC Air Plenum Box with Multiple Duct Interfaces for Fresh Air Ventilation System. If your project needs a non-standard size, a specific wall thickness, a particular colour or a branded face plate, we can build the tooling and run a trial batch for approval before committing to a full production run. Typical custom development takes two to four weeks from drawing approval to first article, depending on the complexity of the part.
Confirm the exact size or model you need against the specification table below. Where a project mixes sizes on one run, check that every transition is made with a matching reducer rather than by forcing parts together — the latter is the single most common cause of leakage and pressure loss on site.
The material and layer build-up determine how the product behaves over a 15–25 year service life. Read the construction column carefully: two products that look identical on a photograph can differ entirely in wall thickness, insulation layer and fire performance.
| Item | Specification |
|---|---|
| Available Sizes / Models | Customized size; 4-way / 5-way / 6-way outlets; custom configurations supported |
| Description | Customizable length, width and height; multiple flat duct outlets available; round top inlet compatible with standard circular ducts; side outlets match underfloor flat ventilation pipes; embedded underfloor installation; port quantity, position and size can be customized |
| Material / Construction | Metal casing: galvanized steel / aluminized zinc steel / stainless steel optional; internal insulation material optional |
Combine with our custom insulated distribution box, metal distribution box, PVC rectangular flat duct and long strip floor air outlet.
GUANDE manufactures Custom Underfloor Air Distribution Box, Metal HVAC Air Plenum Box with Multiple Duct Interfaces for Fresh Air Ventilation System 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. Because we manufacture this product in our own plant, we control the tooling, wall thickness, material grade and quality inspection at every stage — not just the final packing. That means we can produce non-standard sizes, custom colours and private-label versions against your drawings, and we can adjust a production run when a project specification changes. Tell us your target market and we will confirm packaging, labelling and documentation to suit it.
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 casing materials can I choose?
A: Galvanised steel, aluminised zinc steel or stainless steel.
Q: Can port positions be customised?
A: Yes, port quantity, position and size can all be made to order.
Q: Is internal insulation available?
A: Internal insulation material is optional; see also our insulated distribution box.
The southeast corner of the private entrepreneurship park in Huadian Town, Qihui County, Dezhou City, Shandong Province