How to Choose an HVAC Contractor: 10 Questions to Ask

Replacing a central air system is one of the bigger checks most homeowners write — a full HVAC replacement in 2026 typically runs $7,500 to $16,000 installed, and more if ductwork needs work. Here's the part contractors rarely say out loud: the install matters more than the equipment. A mid-tier system installed correctly will outlast and outperform a premium system installed carelessly.

You don't need to become an expert to hire well. You need ten questions, asked in order, and the patience to listen to how each contractor answers. Here's the script.

Questions 1–3: license, certification, and insurance

Start with the paperwork, because it filters out the worst options in five minutes. Every legitimate contractor expects these questions and has the answers ready.

• 1. What's your state contractor license number? Verify it yourself on your state's licensing board website — it's free and takes two minutes. Confirm the license is active and matches the business name on the quote.
• 2. Are the technicians EPA 608 certified? Federal law requires Section 608 certification for anyone who handles refrigerant. Ask specifically about the techs who will be on your job, not just the owner.
• 3. Can you email me a certificate of insurance? You want general liability and workers' compensation, ideally sent directly from their insurance agent. If an uninsured tech gets hurt on your property, the claim can land on your homeowner's policy.

Question 4: will you do a Manual J load calculation?

This single question separates professionals from guessers. Manual J is the industry-standard, room-by-room calculation of how much heating and cooling your specific house needs, based on square footage, insulation, window area, orientation, and air leakage.

The shortcut — "one ton of cooling per 500 square feet" — routinely oversizes equipment. An oversized air conditioner short-cycles: it cools the air fast but never runs long enough to pull humidity out, so you get a cold, clammy house, higher bills, and a compressor that wears out early.

Expect the contractor to actually measure your home, not just read the nameplate on your old unit. Some charge $150 to $400 for the calculation and credit it toward the job — that's reasonable. If someone sizes your system from the driveway, keep shopping.

Questions 5–7: the money questions

A real quote is itemized, flat-rate, and in writing. "New system installed — $12,500" is not a quote; it's a placeholder for future arguments.

• 5. Can I get an itemized flat-rate quote? It should list equipment brand and model numbers, labor, thermostat, new pad, line set, permit fees, and haul-away of the old unit as separate lines.
• 6. What's not included? Duct modifications, electrical panel work, and code-required items like surge protection or a condensate overflow switch can add $500 to $2,000. Better to hear it now than mid-install.
• 7. What's the payment schedule? A deposit of 10 to 33 percent is normal — several states cap it by law — with the balance due on completion. Never pay in full before the work starts.

Questions 8–10: warranty and workmanship

The last three questions cover what happens after the crew leaves — which is where cheap installs get expensive.

• 8. What's your labor warranty, in writing? One year is the floor; two or more signals a company that trusts its installers. This covers the workmanship and is separate from the manufacturer's parts warranty.
• 9. Who registers the manufacturer's warranty? Most brands offer 10-year parts coverage only if the unit is registered within 60 to 90 days — unregistered, it often drops to 5 years. Ask for the registration confirmation in your name.
• 10. Will you pull the permit and schedule the inspection? The contractor should pull it under their own license. "You can pull it yourself and save money" is a dodge — it shifts liability to you and often signals a licensing problem.

Red flags in a suspiciously low bid

When three bids cluster around $12,000 and one comes in at $8,500, the cheap one didn't find efficiency — it left something out. Usually one of these:

Low bids hurt most in the places you can't see: brazed refrigerant joints, gas connections, combustion venting, and high-voltage wiring. That work belongs with a licensed professional — a company like Acme HVAC carries the license, insurance, and certifications above precisely because mistakes there are expensive at best and unsafe at worst.

• No Manual J — they're reusing your old system's size, mistakes included
• Reusing the old refrigerant line set or pad when it should be replaced
• No permit, which means no inspection of the gas, electrical, and refrigerant work
• A vague or missing labor warranty
• Pressure tactics like "this price expires today" or cash-only discounts

How to run the script

Get three bids and ask all ten questions of each contractor. Compare the quotes line by line, not bottom line to bottom line — you're often comparing different scopes of work, not different prices for the same job.

And pay attention to tone. The contractor who welcomes these questions and answers them specifically is showing you how they'll handle your project. The one who bristles just answered them too.