Converting Furnaces to Propane: Kits, Orifices, and WNC's Gas Map
4 min read · from the Cold Mountain Supply counter
Natural gas in Western North Carolina follows the main roads and stops. Past the last main — which happens fast in the coves and up the mountainsides — everything runs on propane tanks. That geography means a furnace leaving the counter has about even odds of needing an LP conversion before it fires.
Gas furnaces ship set up for natural gas. Propane burns at different pressure with a different air-fuel ratio, so the conversion kit swaps burner orifices and re-springs or replaces the gas valve regulator. Running natural-gas orifices on LP over-fires the heat exchanger — it's a safety problem, not a tuning problem.
Kits are appliance-specific: match the kit part number to the furnace model, not just the brand. The instructions specify manifold pressure for the new fuel — set it with a manometer, not by eye, and clock the meter or check with combustion analysis where equipment allows.
The habit that saves return trips: confirm the fuel before the quote. Tank in the yard means LP. If the answer is ambiguous — new construction, recently converted homes — put the kit on the truck anyway. It's a small line item against a forty-minute drive back to the counter.
Everything this guide mentions is on the shelf — same-day will-call pickup, wholesale pricing with a contractor account.