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Gas System & Safety
Gas safe regs, underslung tanks, and why your mate's DIY gas job is terrifying.
Advanced⏱ 15 min read
Contents
1
UK Gas Regulations (The Legal Bit)
**This is not optional.** Gas work in a motorhome/camper must comply with the Gas Safety (Installation and Use) Regulations.
What the law says:
•Gas installations in motor caravans should be carried out by a Gas Safe registered engineer
•Self-builders CAN do their own gas work BUT it must be inspected and certified
•If you sell the van or make an insurance claim, an uncertified gas system is a problem
•Most campsites won't let you pitch with an uncertified system
What needs to be certified:
•Gas pipe runs (copper or flexible stainless steel)
•Gas drop-out vents (mandatory in every gas locker)
•Gas leak testing (pressure test at 20mbar for 15 minutes)
•Appliance connections (hob, heater, water heater)
**Cost to get it done properly:** £200-400 for a certified engineer to inspect and sign off.
**Bottom line:** If you're not confident, pay a Gas Safe engineer. The cost of getting it wrong isn't a fine — it's an explosion.
2
Gas Bottles vs Underslung Tanks
Calor Gas/Propane bottles (most common):
•3.9kg, 6kg, or 13kg bottles
•Available at every petrol station and camping shop
•Easy to swap — no plumbing needed
•Cost: ~£25-35 per 6kg refill
•Takes up interior space in a gas locker
•Need drop-out ventilation in the locker (gas is heavier than air)
Underslung LPG tank:
•Fitted under the van, doesn't take interior space
•Filled at LPG stations (same as autogas)
•Much cheaper per litre than bottle swaps
•Cost: £300-600 for the tank + £200-400 for installation
•Need a certified filler point and level gauge
•**Best for full-timers** — pays for itself in 6-12 months
What we recommend:
•Weekend warrior: 2x 3.9kg Calor bottles in a vented locker. Simple, cheap, safe.
•Full-timer: Underslung tank. The savings add up fast and you never run out at 2am.
Don't do this:
•Run gas pipes through the cab
•Use push-fit plumbing fittings for gas (they leak)
•Forget the drop-out vent (propane sinks — it pools at floor level)
•Use a gas bottle indoors without a proper locker
3
Gas Appliances (What to Fit)
Cooking:
•Thetford or Dometic 2-burner hob (£100-200) — standard choice
•Housed hobs with glass lids save space
•Don't fit a gas oven unless you really need to (they're massive and rarely used)
Heating:
•Diesel heater (Chinese 5kW, £80-150) — uses van's diesel tank, no gas needed
•Gas heater (Truma/Alde) — better heat quality but uses gas fast
•**Most converters use diesel heaters** — cheaper to run and doesn't eat your cooking gas
Hot water:
•Truma Ultrastore (gas + electric): £400-600
•Instant gas water heater (Camplux): £100-200
•Or just boil a kettle (free, no installation needed)
Gas pipe routing:
•Copper pipe or stainless steel flexible pipe (Tracpipe)
•No plastic pipes for gas. Ever.
•Clips every 300mm
•Pass through walls with grommets
•Isolation valve at the bottle AND at each appliance
4
Safety Essentials
Must-haves:
1. **Gas drop-out vents** — one in the gas locker floor, one low in the living space. Gas sinks, so vents go at the bottom.
2. **Gas alarm** — combined CO and propane detector, mounted low (propane is heavier than air). £20-40.
3. **Fire extinguisher** — dry powder, 1kg, mounted near the door. £15.
4. **Fire blanket** — in the kitchen area. £8.
5. **Carbon monoxide detector** — even without gas, if you have a diesel heater. £15.
Maintenance:
•Check hoses annually (replace every 5 years)
•Bubble test connections with soapy water every 3 months
•Never ignore the smell of gas (additive makes it smell like rotten eggs for a reason)
•Turn gas off at the bottle when driving
Emergency:
•Gas smell → open all windows → turn off at bottle → don't use electrical switches → get out
•CO alarm → open windows → get out → call 999
Cost of doing it right: £200-400 for parts + certification
Cost of doing it wrong: everything