How to Hire an HVAC Contractor: What to Ask Before You Sign

localto.co Editorial TeamJanuary 20, 20266 min read

Heating and air conditioning systems are the most expensive mechanical systems in most homes, and the quality of installation matters as much as the quality of the equipment. A properly sized and commissioned HVAC system can run efficiently for 15–20 years. A poorly installed one will struggle to heat and cool properly, consume excess energy, and fail years ahead of schedule.

The first credential to look for is NATE certification (North American Technician Excellence). NATE-certified technicians have passed nationally recognized exams that verify real-world technical knowledge. Beyond NATE, verify that the contractor holds the licenses required in your state — HVAC licensing requirements vary significantly, from state-level contractor licenses to local journeyman and master-level certifications.

One of the most important things a qualified HVAC contractor will do before proposing any equipment is perform a Manual J load calculation. This is the industry-standard process for determining the right system size for your home based on square footage, insulation levels, window area, orientation, and local climate data. A contractor who proposes equipment sizing based purely on what you currently have — without doing the calculation — is a significant red flag.

Get written proposals from at least three contractors, and make sure each one specifies the equipment model number and SEER2 (efficiency) rating, the scope of ductwork modifications, the refrigerant type, who pulls permits, what is included in startup and commissioning, and what warranty terms apply to both parts and labor. Manufacturer equipment warranties are typically 5–10 years, but many only remain valid if the system is installed by a licensed contractor and registered with the manufacturer within 60–90 days of installation.

Ask about maintenance agreements before work begins. Many contractors offer service agreements that include annual tune-ups and priority scheduling, which can extend system life and catch issues before they become expensive failures. Use the localto.co directory to find verified HVAC contractors near you with transparent credentials and customer reviews.

Frequently Asked Questions

What does SEER2 mean and why does it matter?

SEER2 (Seasonal Energy Efficiency Ratio 2) is the current federal efficiency measurement for air conditioners and heat pumps, updated in 2023. Higher SEER2 numbers mean lower operating costs. Federal minimums vary by climate region — most of the US requires at least 14.3 SEER2 for new central AC units. Systems with SEER2 ratings of 16 or above qualify for federal tax credits under the Inflation Reduction Act.

How long does HVAC installation take?

A typical full HVAC system replacement (removing old equipment and installing new) takes one to two days for standard residential work. More complex jobs with significant ductwork modifications, zoning system installation, or custom fabrication can take two to four days. The job should not be rushed — proper refrigerant charging, airflow balancing, and commissioning take time.

Should I replace my furnace and AC at the same time?

If one unit is near end of life, it often makes financial sense to replace both simultaneously. Mismatched systems — especially pairing a new high-efficiency AC with an old furnace — can reduce efficiency, void warranty coverage, and create comfort issues. Most manufacturers design their equipment to work in matched pairs for optimal performance.

What refrigerant does my system use and does it matter?

Older systems (pre-2020) typically use R-22 (Freon), which is no longer manufactured and is very expensive to service. Systems installed between 2010 and 2024 commonly use R-410A. Newer systems use R-454B or R-32, which have lower global warming potential. If your current system uses R-22, factor in high refrigerant costs when deciding whether to repair or replace it.