Most visitors arrive on a phone, at night, with the heat already out
Design for one hand, a small screen and a person who is annoyed before they land.
The high intent HVAC visit is short. They want a phone number that dials, a statement that you serve their area, and something that proves you are not a lead broker. If those take scrolling to find, a share of that traffic leaves.
Put the phone number in the header as a tap target on mobile, not as an image and not tucked into a menu. Keep it visible as the page scrolls.
Hero sections built around a slogan and a stock photograph waste the most valuable screen on the site. Replace the slogan with the two facts a cold household needs and the page starts working immediately.
Desktop matters too, but differently. Planned replacement research happens on laptops during the day, often at an office desk. The same page has to hold a longer, more skeptical read without becoming a brochure.