Every built-in gas grill worth buying is sold in two versions, and they are not the same appliance with a different sticker. Natural gas and liquid propane run at different supply pressures through different-sized orifices. Pick the wrong one and the grill either starves or overfires — and the fix is a licensed professional with a conversion kit, not a knob.
Most people stall on this decision at exactly the wrong moment: the checkout page, with the island already designed. This guide covers the actual mechanical difference, what regulator each configuration needs, what conversion really involves, and the four questions that settle it.
If you only read one section
Choose natural gas if…
- There is already a gas line at or near the patio
- You are trenching for other utilities anyway
- You grill often enough that swapping tanks would annoy you
- You want no fuel storage inside the island
- You are staying in the house long term
Choose liquid propane if…
- There is no gas service to the property, or none reaching the yard
- Running a line would cost more than the grill
- You want the grill working without waiting on a gas fitter’s schedule
- You have cabinet space in the island for a tank
- You may relocate the grill or move house
Why the two are not interchangeable
Propane carries substantially more energy per cubic foot than natural gas. To deliver the same burner output, a natural gas grill has to flow considerably more volume — which is why the orifices, the small metered openings that feed each burner, are drilled larger on natural gas configurations and smaller on propane.
The two also arrive at the appliance at different pressures, and the regulator is what sets that. On KoKoMo built-ins, for example, the natural gas regulator supplied with the unit is set to 4.0 inches of water column. Liquid propane installations call for an 11-inch water column regulator, which is not supplied with the grill and is sourced by your installer.
What is not different: cooking performance. A properly configured grill produces its rated output on either fuel. Anyone who tells you steaks sear better on one than the other is describing a setup problem, not a fuel property.
Conversion is real work, not a setting
Here is something buyers routinely misread. KoKoMo ships its Classic built-in gas grills configured for liquid propane, with a natural gas conversion kit included in the crate. That sounds like natural gas is handled. It is not — the kit is parts, not a completed conversion.
If you ordered the natural gas variant, the orifice change-out still has to be performed before the grill is connected to a natural gas line, and the manufacturer specifies that a licensed gas professional does that work. Factor it into your installation quote rather than discovering it on hookup day with the fitter already onsite.
What the gas professional is actually doing
- Swapping the burner orifices to the correct size for the fuel
- Installing the correct regulator for the supply pressure
- Verifying delivered pressure at the appliance
- Leak-testing every connection in the completed system
- Confirming the installation meets local code, or National Fuel Gas Code ANSI Z223.1 where none exists
Improper installation can affect warranty coverage. This is not the line item to economize on.
Both fuel configurations take the same island cutout — the difference is in the orifices and the regulator, not the footprint.
Where a plumbed line pays off
You never run out
This is the argument that wins most converts. There is no tank to monitor, no gauge to misread, and no moment at 7pm on a Saturday where dinner stops because the flame died. For anyone who cooks frequently, the removal of that failure mode is worth more than the arithmetic suggests.
Nothing stored in the island
A propane built-in needs somewhere for the tank to live, which usually means dedicating a cabinet bay and providing ventilation. Natural gas frees that space for drawers, storage, or a second appliance.
Operating cost is generally lower
In most parts of the country, utility natural gas costs less per unit of delivered energy than tank propane. How much less depends heavily on your local utility rate, your propane supplier, and whether you buy tank exchanges or refills — so the honest answer is to compare your own utility rate against your own propane cost rather than trusting a national average.
It suits a permanent installation
If you are building a masonry island you intend to keep, running the line once and never thinking about fuel again fits the same logic that made you choose built-in over freestanding in the first place.
Where a tank is the smarter answer
No line, no trench, no permit for the line
If gas service does not reach the yard, bringing it there is a separate project with its own excavation, its own inspection, and its own bill. For yards where the grill sits far from the house, that cost can rival the grill itself. Propane sidesteps all of it.
Faster to a working grill
A propane built-in still needs a proper regulator and a professional connection, but it does not need you to wait on a utility, a trenching crew, and a plan review before you can cook.
It moves if your plans do
Grills on propane can be relocated. If there is any chance the island is phase one of a larger project and the grill ends up somewhere else, propane preserves that flexibility.
Some properties have no natural gas at all
Plenty of rural and semi-rural properties run entirely on propane or electricity. If the house has a propane tank already, tying the grill into that system may be simpler than anything involving a utility.
Four questions that settle it
1. Does a gas line reach the grill location today?
If yes, natural gas is almost always the answer. The expensive part is already done.
2. If not, what does a fitter quote to bring one there?
Get the number before deciding. Sometimes it is modest and obviously worth it. Sometimes it exceeds the grill and the decision makes itself.
3. Is the island design final, and does it include a tank bay?
If the cabinetry is already drawn without ventilated tank space, that constrains you toward natural gas unless you revise the plan.
4. How long are you staying?
A gas line is an improvement to the property. If you are staying, it amortizes. If not, propane keeps the money in the appliance rather than the ground.
One more consideration that is easy to miss: if you are also planning a side burner, a power burner, or a second appliance in the same island, they all draw from the same supply. Size that supply for the whole run rather than for the grill alone — your gas professional will calculate the load, but only if you tell them everything that is going in.
Fuel questions we get on the phone
Can I convert my grill from propane to natural gas later?
Often yes, but treat it as a professional service rather than a project. It requires the correct conversion components for your specific model, an orifice change-out, the right regulator, a pressure check, and a leak test. Use manufacturer-approved parts and a licensed gas professional — improvised conversions are both a safety issue and a warranty issue.
Does the cutout change between fuel types?
No. The island cutout, overall dimensions, and clearance requirements are identical between configurations of the same model. What changes is the plumbing behind the grill and the regulator on it. Our cutout dimension reference applies to both.
Does propane produce less heat?
Not in a properly configured grill. The appliance is set up to deliver its rated output on the fuel it was configured for. If a grill underperforms on either fuel, the usual culprits are supply pressure, an incorrect regulator, or a conversion done with the wrong orifices — not the fuel itself.
Where does the propane tank go in a built-in island?
In a dedicated, ventilated cabinet bay, typically behind an access door so the tank can be swapped without dismantling anything. Ventilation matters because propane is heavier than air and pools low. Get this into the island design early; it is a cabinet layout decision, not an afterthought.
Is the regulator included?
It depends on configuration. On KoKoMo Classic built-ins the natural gas regulator is supplied with the unit and set to 4.0 inches of water column; the 11-inch water column regulator required for liquid propane is not supplied and is sourced by your installer. Gas flex connectors are sized by the installer in either case. Confirm what ships with your specific model before your fitter arrives.
Which KoKoMo built-ins offer both fuels?
The gas models are offered in liquid propane and natural gas configurations, including the 26-inch Classic three-burner, the 40-inch Classic five-burner, the 32-inch Professional four-burner, the 40-inch Professional five-burner, and the 30-inch Professional griddle. The built-in charcoal grill sidesteps the question entirely — no gas line, no regulator, no conversion.
Can I run a built-in grill off the house propane tank?
Frequently yes, if the property already has a propane system with capacity to spare. Your propane supplier and a licensed gas professional will confirm whether the tank and regulator setup can carry the additional load, particularly if other appliances draw from it.
Get the configuration right the first time
A grill that arrives set up for the wrong fuel is a delay at best and a freight return at worst. Tell us what is at your island — existing line, planned line, or tank — and we will make sure the unit that ships matches it, along with what your installer needs to have on hand.
Prefer email? Reach us at info@smokeforges.com
Related reading: Built-In vs. Freestanding Grill and How to Plan an Outdoor Kitchen. Browse the KoKoMo built-in collection.
