❄️ Official Rankings
10 Best HVAC in Longmont, CO (August 2026)
We compared 10 hvac serving Longmont and Boulder County, Colorado, and ranked the top providers by verified reviews, ratings, and local reputation — 8,828 customer reviews in all.
The 10 listed below hold an average rating of 4.9 out of 5, led by Groulx Mechanical Heating & Cooling Inc.. Updated for August 2026.
- HVAC ranked
- 10
- Average rating
- 4.9★
- Reviews analyzed
- 8,828
- Area codes
- 720, 303
Groulx Mechanical Heating & Cooling Inc.
⭐ 5.0 · 258 reviews
2447 Winding Dr, Longmont, CO 80504
Flatirons Heating and Air
⭐ 5.0 · 118 reviews
1136 Kimbark St Unit a, Longmont, CO 80501
M and M Heating, Cooling, Plumbing and Electrical
⭐ 4.9 · 3436 reviews
110 S Bowen Cir, Longmont, CO 80501
Welzig Heating, Air, Plumbing & Electric
⭐ 4.9 · 1409 reviews
1831 Boston Ave, Longmont, CO 80501
My Guy Heating and Air (Firestone)
⭐ 4.9 · 1081 reviews
4321 Mulligan St, Longmont, CO 80504
Mountain Valley Plumbing and Heating
⭐ 4.9 · 851 reviews
210 Collyer St, Longmont, CO 80501
Colorado's Finest Heating and Air Conditioning
⭐ 4.9 · 233 reviews
1524 Collyer St, Longmont, CO 80501
Colorado Green Plumbing, Heating and Cooling
⭐ 4.9 · 154 reviews
338 Main St Ste 14, Longmont, CO 80501
Blue Valley Heating & Cooling
⭐ 4.8 · 1231 reviews
1740 Skyway Dr UNIT H, Longmont, CO 80504
HVAC listed here serve Longmont, Boulder County, and nearby ZIP codes including 80501, 80502, 80503, 80504.