Colorado HVAC Pros
Snow-covered gabled roof of a dark house during a heavy snowstorm.

Furnace Installation in Boulder, CO

A new furnace here will run from September through June every year. Tell us about the house, and a licensed contractor who covers Boulder County will get in touch.

Tell us about the job

It takes about a minute.

Step 1 of 3: Equipment
An unfinished basement featuring exposed ceiling joists, a metal HVAC unit with round ductwork, a hanging light bulb, and scattered boxes and debris along the left wall.

Boulder asks a new furnace to work most of the year

Homes here need heat ten months a year, September through June. Winter nights average 17°F, and that is the kind of cold a furnace has to recover from night after night, not once in a while. When a furnace runs that much of the year, what it is rated to do matters. Any non-weatherized gas furnace built since November 2015 has to reach at least 80 percent AFUE, and the unit going into your house should meet that bar or beat it.

Boulder County has logged 161 winter storms and 120 damaging wind events over the past ten years, and power does not always stay on through them. Across Colorado, 13 percent of households lost power for 24 hours or more in 2024. Most furnaces come back on by themselves once power returns, and that is worth confirming when a new one goes in.

10 months
September through June, your furnace is on duty
17°F
the average winter night it heats against
69%
of homes here heat with gas, so most furnaces here burn gas
80% AFUE
the federal minimum any new unit must meet
Isometric cutaway illustration of a single-story house with a dark shingled roof, showing interior rooms with beds and furniture, overhead ductwork, and a gray furnace with a tall flue pipe at the exterior wall.
Your furnace works hardest from October through April.

NOAA nClimDiv, 1991–2020 normals

An unfinished basement featuring concrete block walls, exposed floor joists, and a metal forced-air furnace with ductwork near a central pillar.

A high-efficiency gas furnace would save about $100 a year to run in Boulder County compared with a gas furnace.

  • A high-efficiency gas furnace$470 a year
  • A gas furnace$570 a year

Estimates for a typical Boulder County home, from EIA household energy data, Colorado fuel prices and NOAA climate normals. Your home will differ.

What size furnace does my house need?
The right size depends on your home's square footage, insulation, ceiling height, window count, and layout, so there's no single number that fits every house. A furnace that's too big cycles on and off fast and wears out sooner, and one that's too small runs constantly and never quite keeps up on the coldest nights. With winter lows here averaging 17°F, undersizing shows up fast. A contractor will do a load calculation on your specific house to get the size right.
How do I know it's time to replace my furnace?
The clearest signs are a furnace that struggles to keep the house warm, repairs that keep coming back, or a cracked heat exchanger. Homes here need heat from September through June, so a furnace on its way out gets worked hard for most of the year with little time to rest between seasons. Rising gas bills without any other explanation are another sign the unit is losing efficiency. If a technician has flagged a cracked heat exchanger or a carbon monoxide reading, that's not something to wait out.
Is a high-efficiency furnace worth it?
It depends on how much you use your furnace and what you're replacing. Any non-weatherized gas furnace built new today has to hit at least 80 percent AFUE by law, and high-efficiency models go higher than that, using less gas for the same heat. Homes here need heat from September through June, so that gas savings gets used most months of the year. A contractor can walk through the options for your house and what each one means for your gas use.
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