Casey Mechanical Inc
“Hot water tank broke and we had a new one installed the same day.”
Best HVAC Contractors in Cornwall, ON
11 companies listed · 9 in Cornwall · 1 open 24/7 · 4 open weekends · 10 rated 4.5+
Data verified October 21, 2026
Walker Climatecare
“Brock's professionalism and calm approach in explaining the issue at hand was excellent!”
Marc Viau Mechanical
“We have done previous business with Marc Viau Mechanical and from the front office to the actual install very professional as well as friendly……it's only been a few months but we are very pleased with our choice.”
Baker Heating & Air Conditioning Ltd.
“We are so happy with their service we plan on getting them to perform maintenance on both our units at least once every 2 years.”
McKay Mechanical Inc.
“I highly recommend this company and will most certainly be returning to them to purchase my new air conditioner when this one does finally quit.”
Oscar Ladouceur & Son Ltd
The 11 companies listed for Cornwall, ON handle furnaces and heat pumps in winter and the cooling side in summer. Profiles repeat what each firm publishes about hours, licensing and brands, with ratings and review quotes gathered from public reviews.
Area overview: Cornwall, ON
9 of the 11 companies we list are based in Cornwall; the other 2 serve Cornwall from Summerstown (20 km). The companies on this page are rated from 4.4 to 5.0 across 1,490 reviews; 3 have 50 or more reviews and 10 are rated 4.5 or higher. When customers rate these companies on specific qualities, they most often praise professionalism (94%), responsiveness (82%) and punctuality (78%). 1 is open around the clock; 4 are open on Saturdays and 2 on Sundays. 2 show a licence on their websites. 3 have ten or more years of experience, the longest 26 years. 4 offer emergency call-outs; 2 offer financing or payment plans; 3 give free estimates; 3 are family- or locally-owned and 3 list coupons or special offers. We have a website on file for 9 of the companies on this page; 9 publish a contact page and 8 list a public email. We count these figures across the companies on this page; distances are straight-line, and hours and prices change, so confirm the details with the company before you book.
Do any heating firms listed for Cornwall work on Saturdays or Sundays?
Saturday or Sunday hours show up for 4 of the 11 companies on this page. Saturday is mostly repair work; installations land on weekdays, because supply houses and municipal inspectors keep weekday hours.
Houde Air
“What I like best about him is that he was quick, efficient and helped me through some of the paperwork that was not part of his scope.”
Boileau Mechanical Ltd
“The unit is working better than ever after servicing, he was honest and professional, very clear about what work needed to be done, and all around great.”
M S Mechanical & Sons
“Excellent service, was having issues with my tankless water heater, the tech that came was so nice and professional...”
The Water Heater Guy
“Dylan responded immediately to my text, calling me back, quickly and expertly repaired our tank.”
Wylie Mechanical
“The biggest thing that we liked was that Randy was so kind and understanding, he didn't make us feel pressured and was open to any questions we had.”
Why these companies made our list
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