Luxair Thermobox® Heat Retention Cartridge — 125mm and 150mm
The Thermobox® is a multi-award-winning heat retention cartridge that fits within a 125mm (5") or 150mm (6") ducting vent or round ducting tube. It is a purely mechanical back-pressure shutter solution — no power required, no wiring, and it can be retrofitted to any existing ducting installation.
The Problem It Solves
Every ducted cooker hood extraction system has one weak point: the wall vent or duct outlet through the external wall. When the hood is not in use, this opening allows cold air to enter the building, warm air to escape, and on windy days produces the characteristic noisy flapping sound of standard vent flaps. In draughty or exposed properties this heat loss is continuous and significant — a permanent gap in the building's thermal envelope directly behind the kitchen.
How the Thermobox® Works
The Thermobox® ShutterTec retention system uses three flaps arranged in sequence, sealed by magnets. When closed, the three flaps create two sealed air chambers within the cartridge body. Air is a poor heat conductor — trapping it in sealed chambers creates an insulating barrier that performs up to 20 times better than a standard wall vent. When the extractor is running, air pressure from the motor opens the flaps automatically. When the hood is switched off, the magnets pull the flaps closed, sealing the chambers and restoring the insulating barrier. No power, no sensors, no maintenance.
Key Benefits
For properties in exposed or windy locations, the Thermobox® also eliminates the noise of flapping vent covers and prevents cold air being pushed back into the kitchen by wind pressure — a common problem with single-flap wall vents that standard back-draught shutters cannot fully address.
Ducting Size Guide
Selecting the correct ducting diameter for your motor output ensures maximum extraction performance:
- Below 450m³/hr → 100mm (4") ducting
- 450–750m³/hr → 125mm (5") or 150mm (6") ducting
- 750–2,000m³/hr → 150mm (6") or 200mm (8") ducting
