Propane vs. Wood Fire Pits: What the Fuel Actually Changes

Wood and gas produce heat by different processes, and the difference isn’t preference — it’s that a wood fire ends up as a bed of glowing coals and a gas fire never does. Glowing coals radiate far more effectively than flame does, which explains why a wood fire feels hotter than a gas one that looks bigger — and why gas wins on almost every other axis.

How wood actually burns

Solid fuel burns in two stages, and most of what’s confusing about wood fires comes from not separating them.

Stage one: pyrolysis. Heat drives volatile compounds out of the wood as gas and vapour. That gas is what burns as visible flame above the log — the flame is not the wood burning, it’s the gas released by the wood burning. This stage produces most of the light, most of the smoke, and comparatively little useful radiant heat, because flame is a poor radiator relative to a hot solid.

Stage two: char combustion. Once the volatiles are largely driven off, what’s left is charcoal, and it burns at its surface with little or no flame. It glows. A glowing solid at high temperature is an excellent radiator, and this is the stage that actually warms the people sitting around the pit.

Which is why the useful part of a wood fire arrives late, and why a fire constantly fed with fresh logs is held permanently in stage one — lots of flame, lots of smoke, less warmth than the same wood would have given if allowed to burn down. Moisture compounds it: water in the wood has to be boiled off before pyrolysis can proceed, which is the whole reason seasoned wood is specified, and the mechanism is covered in why fire pits smoke.

How gas burns

Propane or natural gas arrives at a burner already a gas, so there’s no pyrolysis stage and no char stage. It mixes with air and burns in one step, essentially completely, and the products leave as hot gas and water vapour. No embers, no ash, no smoke.

That completeness is the source of every gas advantage: nothing unburnt means nothing to smell, nothing to drift into a neighbour’s garden, nothing to blacken a wall.

It’s also the source of the one real disadvantage. There is no glowing solid, so the radiant output comes from the flame plus whatever the flame heats — which is exactly why gas pits are filled with lava rock, ceramic media, or fire glass. The media isn’t decoration, it’s a substitute ember bed: it absorbs heat from the flame, reaches a high temperature, and radiates. Spread evenly across the burner it delivers noticeably more felt warmth than pushed aside, while burying the burner ports is the opposite failure, restricting gas flow and producing yellow, sooty flame.

Why radiant heat is what matters outdoors at all — rather than air temperature — is in how a fire pit actually warms you.

The trade-offs, laid out

Felt heat. Wood, once it’s down to coals, at a given apparent flame size. Gas needs a larger burner and well-arranged media to compete, and many decorative gas pits are sized for looks rather than output.

Time to useful heat. Gas, instantly. Wood needs a fire laid, lit, and burned down.

Control. Gas, without contest. A valve sets the output and the fire goes out when you close it. Wood is controlled by what you put on it and how you arrange it, on a delay of ten minutes or more.

Smoke and smell. Gas produces neither. For a lot of people in terraced houses and small gardens this decides it outright, because a neighbour’s objection is not a technical problem you can solve.

Ember behaviour. Wood throws sparks and embers, especially in wind and especially with softwoods, which pop as pockets of resin and moisture flash to vapour. A spark screen is genuinely worthwhile rather than optional. Gas produces no embers at all, which is what makes it materially more suitable near a house, a deck, or dry planting — the siting consequences are in how to site a fire pit safely.

Cleanup. Gas: none. Wood: ash, which stays hot enough to reignite for far longer than seems reasonable and must go into a metal container, cold, away from the building.

Cooking. Wood, if that’s the point — coals give even radiant heat. Gas pits are generally not designed for it, and the manual will usually say so.

Wind. Different failure modes rather than a winner: wind carries wood embers unpredictably, and it can blow a gas flame out while fuel keeps flowing. Don’t use either in strong or gusty wind.

Fuel logistics. Wood needs dry, ventilated storage and a supply of seasoned hardwood — bulky and seasonal. Gas needs cylinders exchanged and stored upright, outdoors, away from heat: never indoors, never in a cellar, never in a sealed enclosure.

Cost. Both fuels vary too much by region and season for any figure to be useful. The method that does travel: work out your own cost per evening of use — cylinder cost divided by the evenings a cylinder lasts at your usual setting, or the cost of a volume of seasoned wood divided by the evenings it covers. One season of your own supply settles it; comparing headline fuel prices doesn’t.

The safety differences that aren’t optional

Everything about siting, clearance, and never leaving a fire unattended applies to both and is covered in the siting post. These are the fuel-specific ones:

Gas. Never use a propane appliance indoors, in a garage, in a tent, or in any enclosed or partly enclosed space — combustion consumes oxygen and produces carbon monoxide, and an outdoor appliance has no provision for either. Check hoses and connections for damage before each use. Any permanent gas connection, and any conversion between propane and natural gas, is work for a qualified gas professional. If a burner won’t light, turn the gas off and let it disperse fully before trying again — repeated ignition attempts on an open burner is how people get a flashback.

Wood. Burn only dry, untreated, unpainted natural wood. Treated timber, painted wood, plywood, MDF, and pallets carrying unknown chemistry release harmful compounds when burnt. Never use petrol, lighter fluid, or any accelerant to start or revive a fire. Extinguish completely and douse the ash rather than leaving a covered pile.

What to actually do

1. Decide what the pit is for. Real fire, cooking, and the ritual of building it: wood. Warmth on demand with no smoke and no cleanup: gas.
2. If smoke would trouble a neighbour, choose gas and save yourself the argument.
3. If it’s going near a deck, a wall, or dry planting, choose gas.
4. With wood, let it burn down to coals before expecting heat, and stop feeding it an hour before you want to leave.
5. With gas, spread the media evenly across the burner without covering the ports, and expect to need a larger burner than the flame size suggests.
6. Establish your own cost per evening over a season instead of comparing headline fuel prices.
7. Follow the appliance manual and local burning rules, which differ everywhere and change with dry conditions.