HVAC in Louisville, CO: Heating Service for a Town Rebuilding at 5,300 Feet
Call Us
(720) 764-0399
Same-Day Requests
Speak To Our Team
Serving Louisville from Boulder
Rapid Response
Heating a home in Louisville
Louisville has two kinds of heating system now. As of August 2026, 532 of the 550 homes the Marshall Fire destroyed have been rebuilt or have started rebuilding, each with a new furnace or heat pump installed under the City’s current codes. Around them stands a housing stock with a median build year of 1991, a fifth of it from before 1980. Boulder HVAC Pros serves Louisville from Boulder, one city west. This page is about what heating a home here actually involves, on both sides of that line, and what to do when yours stops.
Louisville is a Boulder County city of about 8,300 housing units at roughly 5,340 feet, where three homes in four heat with utility gas and the median house dates from 1991. Elevation, housing age, fuel, and who serves the address decide most of what goes right or wrong with a heating system here, so each has its own section below, with the rebuild in its place.
Elevation: what 5,340 feet does to a furnace
The U.S. Geological Survey puts the town centre at about 5,336 feet above sea level. Air is thinner here, and so is the natural gas in the line, and a gas furnace only burns cleanly when the two reach the burner in the proportion its maker designed. Manufacturers write that into their instructions. Goodman’s installation manual for its GM9S8 furnaces requires that “when this furnace is installed at high altitude, the appropriate High Altitude orifice kit must be applied,” and notes that a different pressure switch may be needed. It also prohibits derating by turning the manifold pressure down, because thin air and low pressure together “may cause incomplete combustion, flashback, and possible yellow tipping.” That clause applies to a 1990s furnace and to a 2025 rebuild alike. Incomplete combustion is how carbon monoxide is made.
Housing age: a 1991 median, and 550 homes newer than the survey
The Census Bureau’s 2019–2023 American Community Survey puts the median year built for Louisville’s 8,304 housing units at 1991; 20.0 percent were built before 1980 and 23.9 percent in 2000 or later. Read that survey with one Louisville-specific caveat: it pools responses from 2019 to 2023 and records only 92 units built in 2020 or later, so the Marshall Fire rebuilds, 532 of 550 homes rebuilt or under way by August 2026 on the City’s count, are mostly not in it. The real stock is therefore older at the median than the number suggests in the untouched neighbourhoods, and brand new in the rebuild area. The pre-1980 fifth has usually been through several furnaces, and the questions there are about what the last replacement left behind: an undersized return, a flue sized for an older appliance, a control cable short one conductor.
Your next step
If your furnace is struggling, or you are deciding whether to replace it before the Xcel deadline, call Boulder HVAC Pros on (720) 764-0399. Have the furnace’s rating plate, your gas and electric bills, and the house’s build year, or its rebuild permit, to hand; those settle most of the questions on this page before we arrive.
HVAC services in Louisville
For most homes here the work is gas heating in winter, cooling in summer, and a water heater in between. Here is how each service applies to houses here, with the page that covers it in full.
Furnace repair. With three in four homes on gas, this is the January call. On the pre-1980 fifth the fault is often downstream of the furnace itself, in a flue, a return or a control that the last replacement inherited; on a 1990s house it is more often a sensor, an igniter or a pressure switch; on a rebuild the question is commissioning or warranty. The altitude kit is the first thing we check on any of them. Start with furnace repair for Louisville and Boulder County homes.
Furnace replacement. A 1991-median housing stock outside the rebuild area means a large share of furnaces here are at the age where replacement is a decision rather than an emergency. The City requires a permit to replace a furnace, A/C or water heater, and since December 2025 that work is inspected against the 2024 mechanical and fuel gas codes. See furnace installation, including what the City permit involves.
Heat pumps. With a fifth of homes already heating electrically and Xcel rebates running through 2026, a cold-climate heat pump paired with the existing gas furnace as backup is a live option here. Read heat pump installation for Boulder County homes and heat pump repair.
Air conditioning. Louisville’s local amendment to the 2023 electrical code requires GFCI protection on every new outdoor condensing unit, which changes what a compliant install costs and looks like here. See air conditioning installation and AC repair.
Maintenance. An annual inspection is the one service that pays for itself on an older furnace here: combustion check, static pressure, flue condition. It does not need a permit; replacement does. See heating maintenance and tune-ups.
Water heaters. A replacement water heater needs a City permit, the same as a furnace. See water heater services.
When it will not wait. A furnace out on a January night in a house full of people is an emergency call: emergency HVAC repair.
Why homeowners in Louisville call Boulder HVAC Pros
- We are based in Boulder, one city west.
- We know that a furnace here has to be set up for 5,300 feet, and the altitude kit and pressure switch are the first thing we check on every gas appliance here.
- We know the difference between the town's pre-1980 fifth, its 1990s core and its rebuild area, and we ask which one you live in before we quote, because the right answer is different in each.
- And we know the City's process: a furnace, A/C or water heater replacement needs a permit, HVAC inspections are requested through the City's online portal rather than arranged with the homeowner directly, and since December 2025 the work is inspected against the 2024 codes with the GFCI amendment on top.
Why this winter, in Louisville
- the federal 25C credit for efficient heating equipment applied only to property placed in service before December 31, 2025, and any blog still promising a federal heat pump credit for a 2026 install is out of date. What ended and what remains is kept current in our rebates guide.
- Xcel's heat pump rebates have a hard edge: install and invoice by December 31, 2026, with applications accepted through September 30, 2027. A gas-heat Heat Pump Bonus takes effect on October 1, 2026, with amounts that vary by efficiency rating, and since November 16, 2025 the bonus is no longer available to homes with existing electric heating, though the standard rebate still is. For the three in four homes here on gas, this winter is the window the bonus was written for. Xcel does not publish the amounts; they come from the contractor's quote, and Xcel's page adds that rebates are open to its Colorado residential electric and/or natural gas customers and cannot exceed the installation cost.
- this is the first full winter under the 2024 codes the City adopted on December 6, 2025. A replacement permitted now is inspected against them, and a new outdoor unit carries the GFCI requirement.
How Louisville heats: three in four on gas
The same survey’s house-heating-fuel table records 7,963 occupied homes: 77.1 percent heat primarily with utility gas, 21.4 percent with electricity, and almost none with bottled gas or wood. Three caveats travel with those numbers. The survey counts one primary fuel per home, so a heat pump paired with a gas furnace shows up as one or the other; the figures centre on about 2021; and “electricity” covers baseboard and resistance heat as much as heat pumps. The rebuild is the fourth caveat, and it cuts the other way: 550 homes fitted with new equipment in the rebuild years after the fire, under an energy code the survey never saw. What the table does say is that a heating call here is, three times in four, a gas furnace or boiler call, and that an electric minority large enough to make a heat pump conversion unremarkable already exists.
Who serves this address: Boulder County, Xcel, and a 2024 code
Louisville is entirely in Boulder County. The City’s own emergency-preparedness page states that “Xcel Energy is Louisville’s energy provider for residents and businesses,” so an electric bill here is an Xcel bill; the City does not state the gas provider on the pages we found, so check the name on yours before assuming a rebate applies. Xcel’s furnace rebate, for a 95 percent AFUE unit replacing a non-condensing one, is tied to holding Xcel gas service, and its heat pump rebates go through a contractor in Xcel’s Trade Partner Network unless you fit a mini-split yourself. Boulder County’s EnergySmart programme is income-qualified only for 2026. The City adopted the 2024 ICC codes, effective December 6, 2025, and adds a local electrical amendment: GFCI protection is required for every new outdoor air-conditioning unit in Louisville.
Louisville heating FAQ
Do you need a permit to replace a furnace in Louisville?
Yes. The City’s permit-requirements page lists “Replacing your A/C, furnace, or water heater” as work that needs a permit, alongside decks and basement finishes. Inspections are requested through the City’s Citizen Self Service portal, with a 4:00 PM cutoff for next-business-day requests, and the City notes that furnace, A/C and water heater inspections follow their own procedure and are not arranged with homeowners directly. Since December 6, 2025 the work is inspected against the 2024 ICC codes.
Which utility serves Louisville, and does it affect rebates?
The City states that Xcel Energy is Louisville’s energy provider for residents and businesses. It does not name the gas provider on the pages we found, so check your gas bill. Xcel’s furnace rebate requires Xcel gas service and a 95 percent AFUE unit replacing a non-condensing one; its heat pump rebates require an Xcel electric or gas account and, unless you install a mini-split yourself, a Trade Partner Network contractor. Eligibility depends on which utility serves your address. Check before assuming.
How old are Louisville homes, and why does that matter for heating?
The 2019–2023 American Community Survey puts the median year built at 1991, with 20.0 percent of 8,304 units built before 1980 and 23.9 percent in 2000 or later. It records only 92 units built in 2020 or later, so the 550 Marshall Fire rebuilds are mostly outside it. Older homes have usually been through several furnaces; rebuilds have new equipment under new codes; the questions are different in each.
Do most Louisville homes heat with gas or electricity?
Gas. Of 7,963 occupied homes, 77.1 percent heat primarily with utility gas and 21.4 percent with electricity, per the same survey. The survey counts one primary fuel per home and cannot separate heat pumps from baseboard, so the electric figure is not a heat pump adoption rate. It does show that a heat pump conversion is not exotic here.
Will there be heat pump rebates in Colorado in 2026?
The federal 25C credit ended for equipment placed in service after 2025. Xcel’s heat pump rebates run through 2026, with install and invoice by December 31, 2026; the amounts vary by equipment and Xcel does not publish them. Boulder County’s EnergySmart rebate is income-qualified only in 2026, at 50 percent of project cost up to an annual cap, for households at or below 100 percent of area median income. Amounts change; check Xcel’s and EnergySmart’s pages, or our guide to what ended and what remains, before counting on a figure.
Does Louisville require anything special for a new air conditioner?
Yes. The City’s local amendment to the 2023 National Electrical Code, section 210.8(F) exception 2, requires GFCI protection for all new outdoor air-conditioning units within Louisville. A compliant install includes it; ask any installer, including us, to show it on the invoice, and ask for the altitude kit on any gas furnace the same way.