How can I tell if a gas fireplace or log set is set up for natural gas or propane?
Check the rating plate — a metal label inside the firebox, behind the louver, or on the frame. It states the fuel: NAT or NG for natural gas, LP or PROP for propane. Don't judge by the flame or the logs; the plate is the only reliable answer, and running the wrong fuel is dangerous.
The rating plate is the source of truth
Every listed gas appliance carries a rating plate, and by code it names the fuel it's set for. Look on the firebox floor, behind the lower louver or grille, or on the side of the frame — a stamped metal or foil label listing the model, BTU input, and the fuel. Natural gas shows as NAT or NG with a higher BTU input and manifold pressure around 3.5 inches of water column; propane shows as LP or PROP at roughly 10 to 11 inches. If a conversion kit was installed, a good tech leaves a sticker noting the change.
Small parts, big clues
The burner orifice — the tiny brass fitting that meters gas into the burner — is drilled larger for natural gas and smaller for propane, and it's often stamped with a drill number. You generally can't read it without partly disassembling the burner, which we don't recommend you do yourself. The regulator can carry an LP/NG selector or a stamped setting too. These are tech-level checks on a live gas appliance, not counter guesses.
Don't trust the flame
Homeowners often try to eyeball it, and that's the trap. The subtle real differences — propane a touch taller and more yellow, natural gas a bit crisper — are easy to confuse with a flame that's simply misbehaving, and a sooty, weak, or oversized flame is exactly what a wrong-fuel setup produces. So the flame that looks off is the one you most need checked, not the one you can diagnose by eye. If you've moved into a home and don't know its history, or you're bringing an old unit to a new house, have it verified before first use. We confirm fuel on every service call. Call (828) 545-0525.
How we can help
Related questions
- How do I know if my house has natural gas or propane?
- What happens if you run a natural gas fireplace on propane without converting it?
- Do natural gas and propane flames look different in a fireplace?
- What is an orifice in a gas fireplace and why does it matter which fuel I use?
- Are all gas fireplaces convertible between natural gas and propane?
- How do I find out if natural gas is available on my street?
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