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Gas Ventilation Catering Trailer

by Otello
(Inverness)


Hi,

I'm working on a catering trailer at the moment and I'm trying to figure out my ventilation for my two gas appliances that total up to 23kW of output. The trailer is 2mx3mx2.13m in diameter, and it has three open roof vents and one wall one, non-electric and just standard. What kind of additional ventilation might I need? Will I need one considering the serving window will be open when I'm working?

Any kind of help is much appreciated!

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Apr 22, 2025
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starstarstarstarstar 		Gas Ventilation in Catering Trailers: What You Need to Know
by: MobCater

Hiya,

Great to hear you’re setting up your trailer—it sounds like you're nearly there! You're right to be thinking about ventilation now, especially with 23kW worth of gas appliances in play. That’s a decent amount of heat and gas output, and the right airflow is essential for both combustion safety and legal compliance.

First: Know the Rules
In the UK, any catering trailer using LPG gas appliances must comply with the UKLPG Code of Practice 24, Part 3, and Gas Safe regulations. This ensures proper air flow for:

Safe combustion

Removal of combustion gases (like carbon monoxide)

Keeping the working environment cool and breathable

1. Combustion Air Requirements
Your gas appliances need a constant supply of fresh air to burn properly. For gas appliances totaling 23kW, the typical calculation is:

10cm² of fixed ventilation per kW of total appliance input

So:

23kW x 10cm² = 230cm² of permanent low-level ventilation
You’ll also need high-level ventilation to allow hot gases and air to escape.

2. Passive Vents vs. Active Extraction

You’ve mentioned three roof vents and one wall vent, which is a great start—but here’s the thing:

Passive vents (non-electric) can help a bit, especially when the serving hatch is open

But they often aren’t enough alone, especially with gas appliances pushing out heat and fumes

What You’ll Likely Need:

Low-level permanent air vents (grilles, not closable) to feed fresh air in

High-level venting, ideally mechanical extraction (i.e. a fan system or canopy extractor)

An extraction canopy over the cooking appliances is strongly recommended for this setup

Serving hatch open does help, but it won’t be considered reliable or permanent ventilation in the eyes of a gas engineer or during a safety inspection.

3. Ventilation System Design Tips

Install a powered roof or wall extractor with a switch (but NOT on the same circuit as the gas)

Canopy hoods should have grease filters and be ducted outside the trailer

Use stainless steel ducting and splashbacks for easier cleaning and compliance

4. Before You Open: Get Gas Safe Signed Off

To legally operate and insure your trailer, a Gas Safe registered engineer must inspect and certify the installation. They’ll look at:

Your ventilation setup

Appliance installation

Gas pipework and isolation valves

Leak testing and flame failure devices

Don’t skip this part—no engineer’s sign-off, no trading license.

Summary (Quick Checklist)

Requirement Details
Total kW 23kW
Low-level ventilation Min. 230cm² permanent
High-level ventilation Passive is OK, mechanical extraction preferred
Canopy Strongly advised over cooking appliances
Serving window open Helps, but not enough on its own
Gas Safe engineer Must inspect and certify

Hope this gives you a starting points, please note. The information provided here is based on practical experience and industry guidance, but always consult a qualified Gas Safe-registered Commercial Mobile Catering (CMC) engineer for up-to-date, site-specific advice and certification—this advice is for general guidance only.

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