12 Best Furnace Replacement Companies in Longmont, CO (2026)
Why Longmont, Colorado homeowners replace furnaces more in shoulder seasons
Longmont's spring and fall temperature swings strain older heating systems, so many homeowners turn to the best furnace replacement companies in Longmont, CO during shoulder seasons to avoid winter delays. Booking with the best furnace replacement companies in longmont co during milder months improves scheduling, permit coordination, and parts availability. Local installers also time swaps to avoid winter rush.
Quick Picks
Awards based on the same publicly available signals as the Vouched Score, including provider-stated certifications and dealer status. Not independently verified.
Which Longmont providers handle emergency furnace swaps and long warranties?
| # | Provider | Score | Years | Best for | |
|---|---|---|---|---|---|
| 1 | WWelzig Heating, Air, Plumbing & Electric | 90 | 4.9 (1,445+) | 32+ | ★ Highest Vouched ScoreHonest Replace-vs-RepairFurnace + AC Changeout |
Editorial: Heat pump installations for ducted air-source systems are listed on Welzig's service pages. NATE-certified technicians are listed among their credentials. Welzig reports 30+ years serving Boulder County homeowners since 1994. Longmont's seasonal cold winters and warm summers make correct heat pump sizing important. Online mentions note same-day and emergency response availability. Strengths:
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| 2 | MM and M Heating, Cooling, Plumbing and Electrical | 86 | 4.9 (3,520+) | Gas Furnace ReplacementNATE-Certified Installer | |
Editorial: M and M leads with specialist furnace repair work and diagnostics in Longmont. The company states it employs NATE-certified technicians. Emergency Response is advertised as 24/7 with same-day availability. The loyalty membership lists scheduled maintenance reminders and tune-ups. Front Range winters make prompt no-heat response important for Longmont homeowners. Strengths:
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| 3 | MMountain Valley Plumbing and Heating | 84 | 4.9 (875+) | 19+ | High-Efficiency (95%+ AFUE) Upgrades |
Editorial: Mountain Valley advertises furnace replacement and high-efficiency equipment options. Founded in 2007, 15+ years serving Northern Colorado homeowners. Their Longmont headquarters helps with Xcel rebate programs and mountain-climate installs. Mountain Valley states flat-rate pricing and same-day emergency response are available. Reviewers frequently name technicians and note clean job sites. Strengths:
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| 4 | BBlue Valley Heating & Cooling | 83 | 4.8 (1,280+) | ||
Editorial: Blue Valley focuses on AC repair and installs, including ductless mini-split systems. Blue Valley states 30+ years in the field. Longmont's high-altitude cooling loads influence their equipment choices and sizing. The company advertises emergency service (24/7) for no-heat or no-cool calls. Local reviewers describe clear diagnostics and multiple plan options. Strengths:
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| 5 | MMy Guy Heating and Air (Firestone) | 82 | 4.9 (1,110+) | ||
Editorial: My Guy lists furnace replacement and installation experience for Longmont homeowners. The company states same-day emergency response for heating outages. My Guy advertises financing options for high-ticket system changeouts. Local winters in Longmont increase demand for reliable gas-furnace commissioning and prompt service. Strengths:
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| 6 | TTNT Home Services - Longmont | 81 | 4.8 (860+) | 10+ | |
Editorial: Cold-climate heat pump installation is listed as a specialty on their site. GoodFellas notes a company history stretching back 10+ years. Longmont winters and Front Range temperature swings make right-sized heat pumps important locally. Customer reviews highlight punctuality and clear pricing during service visits. Strengths:
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| 7 | GGroulx Mechanical Heating & Cooling Inc. | 79 | 5.0 (265+) | ||
Editorial: Groulx Mechanical advertises same-day service for urgent heating needs. The company lists financing options on its website. Groulx Mechanical notes its technicians are licensed and insured. Family-owned longmont firms can help with winter heating demands at altitude. The site highlights high-efficiency heating and heat-pump installations. Strengths:
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| 8 | KKJ Thomas Mechanical | 79 | 4.9 (275+) | ||
Editorial: KJ Thomas Mechanical leads with furnace replacement experience and a strong high-efficiency focus. The company states 40+ years of combined tradesman experience. KJ Thomas notes they help homeowners qualify for Xcel Energy rebates in Boulder County. The website advertises same-day emergency response for urgent heating needs. Reviews and site copy emphasize tidy, detail-focused installs and clear communication. Strengths:
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| 9 | CColorado's Finest Heating and Air Conditioning | 77 | 4.9 (235+) | ||
Editorial: Furnace repair work leads their website, with diagnostic services advertised for all furnace brands. Jordan's team states NATE-certified technicians handle gas and combustion issues. The company notes 24/7 emergency response and same-day service availability. Local winters in Longmont make quick no-heat response essential during freezes. Review excerpts show same-day fixes and clear explanations of needed repairs. Strengths:
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| 10 | CColorado Green Plumbing, Heating and Cooling | 74 | 4.9 (150+) | 46+ | |
Editorial: Colorado Green lists furnace replacement and HVAC installations with same-day replacement availability. Strengths:
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| 11 | FFlatirons Heating and Air | 71 | 5.0 (130+) | ||
Editorial: Flatirons Heating and Air is based in Longmont, Colorado. The company lists a public website for customer reference. Their business location is 1136 Kimbark St Unit a in Longmont. Longmont's high-altitude, cold winters often increase indoor dryness and filtration needs. Local reviewers have contributed a substantial number of Google opinions. Strengths:
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| 12 | JJim Needham Heating Cooling Plumbing and Drain | 69 | 4.9 (105+) | ||
Editorial: Jim Needham lists central AC installation and condenser swaps on its service pages. The company notes over 100+ years of combined experience. Jim Needham advertises financing and instant online estimates. Denver's high-altitude summers and dry winters affect cooling loads in Thornton. Strengths:
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Typical Furnace Replacement costs in Longmont, CO (2026)
Last updated
Estimated ranges for Longmont, CO. Actual cost varies with home size, equipment, and scope — always request a written quote for your job.
| Service | Typical range |
|---|---|
| Full gas furnace replacement (80% AFUE, installed) | $3,100–$6,750 |
| High-efficiency condensing furnace (95%+ AFUE, installed) | $4,700–$9,900 |
| Modulating / two-stage variable-speed (ECM) furnace upcharge | $625–$2,100 |
| Condensing-furnace venting + condensate conversion (80%->95% AFUE) | $625–$1,850 |
| Gas line / electrical / permit modification (changeout) | $155–$935 |
| Electric furnace / air-handler replacement (installed) | $2,100–$5,200 |
Nearby Colorado furnace replacement pricing: Arvada · Aurora · Boulder
See broader context: Furnace Replacement pricing in Colorado · Furnace Replacement pricing nationwide
How were installers judged on emergency response, licensing and longevity?
This guide evaluated 12 Longmont furnace replacement providers on emergency response, certifications, years in business, pricing models, and customer ratings. The most-weighted signals were Google review metrics and provider-stated emergency and certification claims, with BBB records consulted for accreditation checks.
- M and M Heating, Cooling, Plumbing and Electrical is NATE certified and lists 24/7 emergency response; Google Maps shows a 4.9/5.0 rating with 3,520+ reviews.
- Welzig Heating, Air, Plumbing & Electric reports 30+ years in business and free estimates; its 24/7 response and ratings appear in Google Maps data.
- Mountain Valley Plumbing and Heating lists flat-rate pricing and same-day emergency service; the company notes state rebate program assistance on its site.
- Colorado Green Plumbing, Heating and Cooling is NATE certified and reports 45+ years in business, per provider listings and Google reviews.
- Groulx Mechanical and Flatirons Heating and Air show exceptionally high review sentiment scores; those Google review signals influenced ranking weight.
Selection leaned on Google review metrics and verifiable provider claims, with BBB records used to cross-check formal accreditations where available.
How do I choose a furnace replacement contractor in Longmont?
- Verify business license and NATE certifications where listed.
- Compare emergency response windows and after-hours fees.
- Confirm pricing model and ask for a written estimate.
- Request references and check Google reviews for recent trends.
- Check BBB records for complaints and accreditation status.
5 furnace issues Longmont homes see when cold snaps hit — and what to ask a tech
The most common furnace problems in Longmont stem from sudden freeze-thaw cycles and shoulder-season temperature swings that stress older systems. When evaluating options, consult local furnace replacement reviews Longmont CO to compare emergency response and winter reliability before scheduling service or replacement.
- Cracked heat exchanger. Freeze-thaw cycling and repeated short runs during Longmont cold snaps can stress metal and cause cracks that need prompt inspection.
- Intermittent ignition or pilot failures. Rapid temperature swings and sporadic winter use in Longmont make ignition components fouled or misaligned, causing no-heat calls.
- Thermostat and control cycling. Thermostats often short-cycle in Longmont because outdoor swings confuse sensor calibration, which raises energy use and wears components.
- Blower motor strain and bearing wear. Extended runs during prolonged cold snaps in Longmont increase blower duty cycles, accelerating motor and belt failure in older units.
- Blocked exhaust or condensate freeze. Cold snaps can freeze vent terminations and condensate lines in Longmont, causing pressure switches to trip and systems to lock out.
When preparing for a tech visit, request a written diagnostic and ask about emergency response windows and winter-ready installation options. To compare evaluated providers and request a free quote, see #contact.
How Longmont’s population size and local rules shape furnace replacement timing
Longmont’s wide shoulder-season swings and near-freezing nights drive earlier furnace replacements in neighborhoods like Old Town, Sunset, and Southridge to avoid winter failures. Local permitting and jurisdictional licensing also lengthen lead times. Homeowners often schedule replacements in fall to secure certified technicians and to align with permit windows.
Longmont's shoulder-season temperature swings increase wear from repeated short heating cycles. That stress raises the risk of heat-exchanger fatigue and ignition failures during cold snaps.
Because Colorado has no statewide HVAC license, municipal permitting determines installer qualifications and timing. Look for evaluated providers who document local permit experience and municipal inspection familiarity.
Emergency service demand rises with sudden freezes in Longmont, increasing after-hours replacement requests. Many evaluated providers advertise emergency service availability, so prioritize contractors who offer 24/7 response.
Housing stock turnover in a city of about 98,282 means frequent retrofit and efficiency upgrades. Evaluated providers list furnace type expertise and efficiency-tier installs, which helps match replacements to home geometry and code requirements.
Local regulations in the North DOE region require minimum equipment efficiency for cooling. While that targets A/C, replacement contractors often bundle efficiency-tier recommendations for paired furnace and A/C work.
Which Longmont furnace replacement questions affect cost and permit timing?
- How do I get a quote from these furnace replacement companies?
- Submit one request on this page and we send it to the vetted furnace replacement pros in Longmont, CO listed here. They send quotes back — no obligation.
- How much does furnace replacement service cost in Longmont, CO?
- Full gas furnace replacement typically runs $3,100–$6,750, and high-efficiency condensing furnace runs $4,700–$9,900 in Longmont, Colorado. See the Furnace Replacement pricing table on this page for the full per-service breakdown.
- Do Longmont furnace replacements require city-issued permits and municipal inspections?
- Yes. Colorado lacks a statewide HVAC license, so Longmont relies on city permits and inspections. Contractors must follow Longmont municipal permit processes and inspection schedules when replacing furnaces.
- Which Longmont jurisdiction enforces equipment efficiency rules for paired furnace and A/C replacements?
- Longmont sits in the North DOE region, which enforces a minimum 13.4 SEER2 for residential central air conditioning. Contractors often advise matching furnace and A/C efficiency to meet local code and inspection expectations.
- Can a Longmont contractor complete a same-day furnace replacement during a cold snap?
- Some Longmont providers offer same-day replacement, but permits or inspections can delay completion. Ask providers about their municipal permit experience and emergency service availability before booking.
- Are special permits or qualifications required for gas furnace replacement in Longmont?
- Yes. Gas work typically needs local permits and certified technicians familiar with Longmont inspection rules. Verify a contractor’s local permit experience and gas-handling credentials before scheduling gas work.
- How does Longmont's SEER2 requirement affect replacing a furnace and air conditioner together?
- SEER2 minimums apply to the A/C portion in the North DOE region, and inspectors check paired-system compliance. Coordinating both replacements simplifies permitting and can reduce re-inspection delays.
- How do I find a high-efficiency furnace specialist in Longmont?
- Look for contractors who list high-efficiency installations, cite manufacturer-dealer affiliations, and show municipal permit experience. Ask for documented installs and NATE or manufacturer certification as vetting signals.
- What factors most affect pricing and permit timing for furnace replacement in Longmont?
- Key factors include permit complexity, the home's age and access, required duct work, and seasonal demand. Permits and inspection slots can add lead time, especially during fall shoulder-season demand.
- Do commercial furnace replacements in Longmont follow different permit rules than residential jobs?
- Yes. Commercial projects often require different permit types, larger inspections, and specialized HVAC credentials. Confirm which Longmont department issues commercial HVAC permits and who will sign off on inspections.