A bad HVAC installation wastes 20–30% of your system's efficiency — even if you bought the best equipment. The contractor you choose matters far more than the brand. Here are the 10 questions that separate competent installers from the ones who will cost you thousands in future repairs and energy bills.
1. "Are you licensed, bonded, and insured? May I see proof?"
Licensing requirements vary by state. In California, HVAC contractors need a C-20 license from the Contractors State License Board. In Texas, they need a TACL from the Department of Licensing and Regulation. Ask for the license number and verify it on your state's licensing board website — this takes 60 seconds and eliminates unlicensed operators instantly.
Insurance: They need general liability (minimum $1 million) and workers compensation. If a worker is injured on your property and the contractor lacks workers comp, you could be liable.
2. "Will you perform a Manual J load calculation?"
This is the single most important question. A Manual J calculation determines the correct size for your system based on your home's square footage, insulation, window area and orientation, ceiling height, and local climate. Contractors who size equipment "by rule of thumb" — e.g., "400 square feet per ton" — are guessing. An oversized system short-cycles (turning on and off rapidly), which reduces efficiency by 15-25% and shortens equipment life. Walk away if they will not do a Manual J.
3. "Can you provide references from the last 6 months?"
Ask for three recent customers and call them. Ask: Was the project completed on time and on budget? Were there any surprises? Would you hire this contractor again? Listen carefully to hesitation.
4. "What brands do you install, and why?"
The brand matters less than the installation. A mid-range Carrier or Trane installed perfectly outperforms a premium Lennox or Daikin installed poorly. But a contractor who installs only one brand may be incentivized by manufacturer rebates rather than what is best for your home. The answer you want: "We install [2-3 brands] because [specific technical reasons about reliability, parts availability, warranty support]."
5. "What is your warranty — labor and parts?"
Standard manufacturer warranties: 10 years on compressor, 10 years on parts, lifetime on heat exchanger for gas furnaces. But labor is not covered by manufacturer warranties. Ask about labor warranty separately. Quality contractors offer 1–3 years of labor warranty. Exceptional contractors offer 5+ years — this signals confidence in their work.
6. "Do you pull permits, and is the cost included in the quote?"
If they offer to skip permits to save money, end the conversation. Unpermitted HVAC work can block a home sale, void your homeowner's insurance, and create safety hazards. Permits cost $100–$500 and include an inspection by the city or county — which is your independent verification that the work was done correctly.
7. "How do you handle the electrical work?"
Heat pumps require a dedicated circuit, and many homes need an electrical panel upgrade (30-50 amps of additional capacity). Ask: Is the electrician a subcontractor or an employee? Are they licensed? Is the panel upgrade included in the quote, or will it be an add-on? A contractor who hesitates on this question has not fully scoped the job.
8. "What is your payment schedule?"
Never pay 100% upfront. Standard practice: 10–30% deposit to schedule, remaining balance due upon completion and passing inspection. If a contractor demands more than 50% upfront — especially for a project under $15,000 — that is a red flag.
9. "How do you size and design the ductwork?"
If you have existing ducts, they must be inspected for leaks (a typical home loses 20–30% of conditioned air through duct leaks). The contractor should perform a duct leakage test and quote for sealing if needed. For new installations, ductwork should be sized using Manual D calculations — the companion to Manual J.
10. "What is your process if I am not satisfied?"
Every contractor says they do great work. Ask: What happens if the system does not perform as promised? Is there a callback procedure? How quickly do you respond to warranty issues? The answer reveals whether they stand behind their work or disappear after the final payment clears.