Air Valve Plenum Box, 125mm Valve x 2 Spigot 75mm EPP

Description

The Casavent AVA-125-75-2-V-EPP is an EPP air valve plenum box that connects a single 125mm ceiling or wall air valve to two 75mm radial semi-rigid ducts, forming the room-end termination of a radial MVHR or MEV system. Moulded from Expanded Polypropylene (EPP), the box combines an insulating, lightweight structure with an aerodynamically profiled interior that keeps pressure drop low as air splits between the two duct spigots.

This vertical-spigot plenum sits between the air valve and the radial ductwork, allowing higher airflow rooms to be served by two 75mm ducts from a single valve position rather than one larger, harder-to-route duct.

125mm Air Valve Neck

2 x 75mm Duct Spigots

EPP Material

217.5mm Length (A)

λ 0.0038 Thermal Conductivity

-25 to +80°C Service Temperature

System Component This plenum box is a system component — it connects a 125mm air valve to 75mm radial ductwork and does not include the valve, ducting, or manifold. These are sold separately.

Insulating EPP Construction Moulded from Expanded Polypropylene with a wall thickness of approximately 8–31mm, the box provides useful thermal insulation (λ = 0.0038 W/(m·K)) around the duct connection, reducing condensation risk and heat loss at the room termination point.	Aerodynamic Internal Profile The profiled internal shape of the EPP box reduces pressure drop compared with a plain rectangular box, helping the connected duct run operate at a lower system pressure for the same airflow.
Dual 75mm Duct Spigots Two 75mm duct connection spigots allow a single air valve position to be fed by two duct runs, useful where higher airflow is required at that valve than a single 75mm duct can comfortably deliver.	Double Duct Fixing Each duct spigot uses a male connection with an internal gasket and EPP outer casing, giving a secure, airtight double-fixing method for the semi-rigid duct.
Corrosion-Free As a moulded plastic component, the plenum box is immune to corrosion, unlike galvanised steel alternatives, giving long service life in damp loft or ceiling void conditions.	Flexible Fixing Options The box can be installed using screws and wall plugs, or with 17–25mm-wide perforated mounting tape, giving installers flexibility depending on the fixing surface available.

Product Overview
Brand	Casavent
Product Code	AVA-125-75-2-V-EPP
Description	Air Valve Plenum Box, 125mm Valve x 2 Spigot 75mm, Vertical, EPP
Orientation	Vertical
Dimensions
Air Valve Neck Diameter	125mm
Duct Spigot Diameter	75mm (x2)
Length (A)	217.5mm
Width (B)	219mm
Height (C)	75mm
Spigot Length (L)	80mm
Technical Data
Material	Expanded Polypropylene (EPP)
Thermal Conductivity	λ = 0.0038 W/(m·K)
Service Temperature	-25°C to +80°C
Reaction to Fire	Class E (EN 13501-1)
Microbial Resistance	Rating 1a, Method A (EN ISO 846:2019)
Air-Tightness	Suitable for ATC2 (D) air-tightness class systems (EN 17192:2018)

What does this plenum box connect?

It connects a single 125mm ceiling or wall air valve to two 75mm radial semi-rigid ducts, terminating a radial MVHR/MEV run at the room.

Why does it have two duct spigots instead of one?

Splitting the airflow across two 75mm ducts allows higher air volumes to be delivered to a single valve position than a single 75mm duct comfortably supports.

What is the box made from and why?

It is moulded from Expanded Polypropylene (EPP), which is lightweight, insulating, corrosion-free, and has good acoustic properties compared with metal alternatives.

How is it fixed in place?

Using either screws and wall plugs, or 17–25mm-wide perforated mounting tape.

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