Reliable Heating Services

Satisfaction on every job.

Welzig Heating and Air is known across Boulder, CO and surrounding areas for our integrity of service and products. By refusing to compromise our standards, we deliver unmatched immediate and lasting benefits. Rest assured, our team of professionals follows exacting protocols for heating system installation, replacement, upkeep, and problem-solving. Whether you’re in need of residential or commercial heating system solutions, we are always the choice that achieves the highest expectations.

Family-owned and operated, Welzig Heating and Air guarantees satisfaction on every job. We offer free estimates on equipment replacement and handle the requirements of every make, model, and style of heating unit. Simply give us a call at (720) 336-3777, no matter the time of day or night. Our experienced technicians remain available and prepared for the most complex challenges, 24/7. To facilitate completion, we also offer multiple financing options, including 60 months financing with approved credit.

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Heating Maintenance, Repair, and Installation

From furnaces and boilers to heat pumps, dual fuel systems, and ductless mini splits, Welzig Heating and Air is the key to winter comfort across Boulder, Longmont, Louisville, and Lafayette, CO. Let us take exceptional care of your essential equipment. Our Comfort Club maintenance plan provides three levels, all with up to 15% discount off repairs, 21-point inspection, and up to 10% off equipment replacement. Take advantage of 12, 24, or 36-month warranties on repairs, priority scheduling and with our platinum coverage, no trip charges.

Heating Service, Furnace Replacement. Heater Installation, Furnace Service, Heating Repair & Furnace Repair Boulder, CO, Longmont, CO, Louisville, CO & Lafayette, CO

Furnace Company Boulder, CO | Heating Repair Longmont, CO | HVAC Company Louisville, CO

HVAC CompanyHVAC ContractorFurnace Company ∴ Boulder, CO ∴ Lafayette, CO ∴ Louisville, CO

Satisfied Customers
They Speak For Us

Our 23-year-old A/C system ran out of “borrowed time” and became too difficult to continue maintaining. With great advice from Casey Welzig,, we replaced the old system with a Bryant Evolution A/C system. Max Loustaunau and Seth Bernhardt did an excellent job with removing the old system and installing the new one. Both of them are great to work with — very professional and very personable. We are really amazed at how much better the new system works!


Dave Kaplan-Gomez and James Miltersen installed my new Tankless Water Heater. Both were polite and professional. Care was taken not to damage anything in my house which I really appreciated. I use Welzig for all my HVAC needs and highly recommend them.


Bob came out to look at our swamp cooler and was remarkably helpful and professional. Not only did he give me a knowledgeable diagnosis, but he also taught me a lot in the process. We’ll be calling him for all future needs with our cooling system.

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