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How Much Extraction Do I Need for a Horsebox Catering Conversion?

Stainless steel extraction canopy mounted inside a catering unit above the fryers and griddle

Stainless steel extraction canopy mounted inside a catering unit above the fryers and griddle

Hello!

I am looking to convert a large RICE horsebox in to a mobile catering unit. I want to be able to have a deep fat fryer, and a gas powered chargrill as the means of cooking. I am a bit lost as to whether or not this will be feasible, mainly because I dont know how much extraction we will need to provide a safe working environment.

Do you have any advcie on extraction? I know I need to have a hood that covers the entirety of the cooking equipment, but how powerful would it need to be? Would this even be acheievable on the structure of the horsebox?

I look forward to your reply, please let me know if I can offer any more informtaion!

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Jul 20, 2026
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by: MobCater

Extraction is the part of a horsebox conversion that catches most people out, and you are right to be thinking about it before anyone starts cutting into the roof.

The first thing to say is that a deep fat fryer and a gas chargrill together are a serious heat and grease load, so this is not a job for a domestic cooker hood. You need a proper stainless steel commercial canopy with removable grease filters, and it wants to overhang the cooking line rather than just sit above it, so the plume of heat and grease is caught before it drifts back into the serving area. A canopy that only covers part of the equipment will leave you working in smoke by the second hour of a busy lunch.

On how powerful the fan needs to be, that gets sized off your actual appliances rather than off a rule of thumb someone posted on a forum. The engineer works out the total heat output of the fryer and the chargrill in kilowatts and sizes the extract volume from that, and a chargrill pushes those numbers up quickly because it is an open flame radiant appliance rather than a sealed one. Give your canopy supplier the exact equipment list and let them quote against it.

The bit people miss entirely is the gas interlock. If you are running gas appliances under a canopy in an enclosed unit, the extraction has to be interlocked with the gas supply so the gas shuts off automatically if the fan fails or was never switched on. Your EHO and your gas engineer will both look for this, and a unit without it will not pass.

You also need air coming in, not just going out. If you pull several hundred cubic metres an hour out of a sealed box with no inlet, the fan fights itself, the appliances starve, and that is exactly how carbon monoxide problems start. A permanent low level air inlet, sized alongside the extract, is part of the design rather than an optional extra. Fit a carbon monoxide alarm as well.

On the structure, a large RICE box will take it, but a canopy and fan assembly is heavy and that roof was never designed to carry a point load, so you will most likely need a frame to spread the weight rather than bolting straight through the panel. Raise it with whoever is doing your fit out early, because it decides where the cooking line can sit.

My honest advice is to get a Gas Safe registered engineer who holds the mobile catering qualification involved before you finalise the layout, not after. Very few engineers hold that specific ticket, and I found it near impossible to get quotes when I needed one, so start ringing round now.

Good luck with it

David

Disclaimer: Gas installation and maintenance must be carried out by a Gas Safe registered engineer. Never attempt gas work yourself. Check gassaferegister.co.uk for qualified engineers in your area.

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