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Natural gas vs LPG instantaneous water heater

Updated: 21 October 2026

You have either a natural-gas meter or LPG cylinders, and a natural gas vs LPG instantaneous water heater is not one appliance with a switch. In this amazon.co.uk set the GASLAND GS318NG is specified as methane at 20 mbar, and the CAMPLUX GX318LP is specified as LPG at 28–50 mbar. Buy the family you already have. The [24kW instantaneous water heater comparison](/hub/hot-water/24kw-instantaneous-water-heater) shows both listings with their shelf prices. Peter F. wrote this on 20 October 2026 from those listings and public UK sources. No lab test was run. A purchase through our links can earn a commission at no extra cost to you.

You have either a natural-gas meter or LPG cylinders, and a natural gas vs LPG instantaneous water heater is not one appliance with a switch.

Our top picks

GASLAND GASLAND GS318NG

Best overall

GASLAND GASLAND GS318NG
8.4/10about £151.99
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CAMPLUX CAMPLUX GX318LP

Best value

CAMPLUX CAMPLUX GX318LP
8.4/10about £239.99
View offer
GEESEN GEESEN RV05

Rank 3

GEESEN GEESEN RV05
7.6/10about £219.00
View offer
On this page
  1. 1.Two gases, two pressures
  2. 2.When the GS318NG is the match
  3. 3.When the GX318LP is the match
  4. 4.Conversion is not a DIY afternoon

Two gases, two pressures

Natural gas in a UK house is mostly methane, at a pressure the appliance is built to see at about 20 mbar. Propane from a cylinder or a bulk tank is a different gas, and the appliance inlet in the GOV.UK propane column is about 37 mbar. The CAMPLUX range of 28–50 mbar must not be collapsed to 37 mbar only, and it must not be read as any bottle will do. A Flexiheat SF14 in the same class is sold as natural gas or as propane: two models, not a driveway conversion unless that manufacturer states a kit. The GEESEN RV05 is propane as well, with no pressure printed, and it is an RV heater rather than a third house option. If the inlet pressure and the injector set do not match, the burner can overfire, underfire, or refuse to light.

When the GS318NG is the match

Choose the GASLAND GS318NG, B0DHBYSJ8C, at about £151.99, when the house has a natural-gas meter and the listing’s 20 mbar methane line is what your engineer expects to see. It does not state an LPG conversion kit, a jet set, or a second gas family. A UK review says the exhaust flue was not in the box, so the fuel match does not include the flue. Skip this heater if your only gas is a cylinder or a bulk LPG tank. Connecting it to Calor-type propane feeds a 20 mbar injector set from the wrong supply. Worcester’s historic combi literature treats about 20 mbar natural gas and about 37 mbar propane as different duties, which is a pattern, not a part number for GASLAND.
GASLAND GASLAND GS318NG

Testsieger

GASLAND GASLAND GS318NG
8.4/10about £151.99
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When the GX318LP is the match

Choose the CAMPLUX GX318LP, B0F7KN3J8H, at about £239.99, when you already have LPG and the installation pressure sits inside the stated 28–50 mbar band. The bullets name that range, a balanced flue at 60/100 mm, up to 24 kW and 12 L/min, and a 60°C ceiling. They do not name natural gas. Two UK reviews used a gas engineer. Most of the stored file is North American cabin use, so it is a weak guide to a UK cylinder install. The specification table says Floor while the sales copy describes a compact indoor unit, which the engineer has to reconcile before the flue is cut. Skip this heater if you have a natural-gas meter. The listing does not tell you to swap butane and propane inside that band yourself. If your regulator is outside 28–50 mbar, neither amazon listing’s claim covers you.

Conversion is not a DIY afternoon

No conversion kit appears in the file for the GS318NG or the GX318LP. Do not re-jet either heater. If a manufacturer later supplies a kit for a stated model, fitting it is still Gas Safe work, and the card has to show that competence. A hose sold for natural gas is not an LPG hose. After any lawful conversion the data plate has to match the gas now in use. The RV05 does not close the gap. It is liquid propane at 12 V, pressure not stated, and its output fields disagree. It is not a donor of jets for the GS318NG. Read the meter or the cylinder label before you order, and let the Gas Safe engineer confirm the inlet pressure.

Common questions

I have a gas meter. Which listing?
The GS318NG, at about £151.99, states methane at 20 mbar. That is the natural-gas match in this set. GOV.UK describes the appliance inlet for group H natural gas as nominally about 20 mbar. The listing still needs a flue the box does not name, and a Gas Safe engineer.
I have cylinders. Which listing?
The GX318LP, at about £239.99, states LPG at 28–50 mbar. Use it when your regulator sits in that band. Do not assume every Calor cylinder is inside the band without reading the regulator. The GS318NG is specified only as 20 mbar methane, and the file has no conversion kit.
Can the installer just change a jet?
Only if the manufacturer provides a conversion for that exact model, and only as Gas Safe work. These two files do not list a kit. Hob manuals that mention jets are not a kit for this water heater. If no kit exists, buy the other model rather than altering this one.
What pressure is UK natural gas, and what is propane?
About 20 mbar for natural gas at the appliance, and about 37 mbar for propane, in the GOV.UK supply-pressure publication. The table has more than one duty, including leisure vehicles, so the live inlet is measured on site. The GX318LP prints 28–50 mbar, which is wider than 37 mbar alone.
Is butane the same as propane?
No. Both are LPG, and they are not interchangeable. Butane and propane use different regulator pressures. The GX318LP’s 28–50 mbar span is the seller’s range, not a statement that you may swap them. If the cylinder label and the data plate disagree, do not connect them.
Will the RV propane heater run a house on mains gas?
No. The GEESEN RV05 is a 12 V camper heater on liquid propane. It does not state a natural-gas pressure, and its kilowatt and BTU lines contradict each other. It is not a way to avoid choosing between the GS318NG and the GX318LP.

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Sources

Public UK sources named below. amazon.co.uk prices, stars and review counts on these three listings were read on 19 October 2026. Page updated 21 October 2026.

  1. Approved Document G, with 2024 amendments (retrieved 19 October 2026)
  2. Gas Safety (Installation and Use) Regulations 1998, regulation 30 (retrieved 19 October 2026)
  3. HSE: gas safety in rented homes (retrieved 19 October 2026)
  4. Approved Document J (2022) (retrieved 19 October 2026)
  5. BS EN 26:2023, gas-fired instantaneous water heaters (retrieved 19 October 2026)
  6. GOV.UK: energy labelling of products (retrieved 19 October 2026)
  7. Water Supply (Water Fittings) Regulations 1999, regulation 5 (retrieved 19 October 2026)
  8. Instant water heaters: electric and gas flow notes (retrieved 19 October 2026)
  9. HSE: who may carry out a landlord gas check (retrieved 19 October 2026)
  10. BS EN 26:2023 CEN summary (retrieved 19 October 2026)
  11. Flexiheat instant gas water heaters (retrieved 19 October 2026)