Furnace Installation & Replacement in Longmont

Much of Longmont grew after World War II, and the 41,680 housing units counted in 2020 include large areas of ranches, split-levels and two-stories from the 1960s through the 2000s. Furnaces from 2000s replacements are the main group coming due now. Prospect New Town, begun in the mid-1990s, has tighter homes on smaller lots; original furnaces there are near 25 years old, and side-yard space for vent terminations can be limited.

At about 4,980 feet, Longmont is among the lowest cities we serve, but furnaces still lose about 20% of their sea-level rating. A 60,000 Btu/h input furnace runs at about 48,000 after high-altitude setup. Correct setup means more than a smaller rating on paper: the burner orifices and manifold pressure are changed to the manufacturer's high-altitude settings, and we confirm the temperature rise falls inside the furnace's listed range. We size from a Manual J. The city's record low is -38°F, set in 1930, but furnaces are sized for the design temperature, not the record, with comfort on the rare extreme nights coming from proper sizing and a tight house rather than an oversized furnace.

New gas furnaces sold in Colorado since January 1, 2026 must meet 14 ng/J NOx or current ENERGY STAR certification, which since July 31, 2026 means about 97% AFUE in the North. Your existing furnace can stay and be repaired. When you replace it, we show the compliance path on the quote. See our NOx guide.

A furnace swap counts as gas and mechanical work, so Building Services needs a permit on file before we start. We submit it and book the inspection. Xcel holds the city's gas franchise, and a rebate tracker reports Xcel ended gas furnace rebates on January 1, 2026.

For electric-side incentives, LPC customers go through Efficiency Works, whose HVAC offers center on heat pumps, including add-on units that keep the gas furnace as backup. Its past rules required work by a listed provider and a claim within 45 days, so verify the current terms before buying. Colorado's $1,000 air-source credit and Power Ahead Colorado's $1,500 cold-climate rebate also apply. Our dual-fuel guide explains pairing a heat pump with a furnace.