Questions to Ask Before Hiring an HVAC Company

An HVAC system is only as good as its installation, and the installation is only as good as the questions you ask before signing. The twelve questions below expose the difference between a company that engineers your system and one that swaps boxes. The two most important are about Manual J sizing and duct testing, because those are the steps box-swappers skip.

Sizing and design

1. Will you perform a Manual J load calculation, or size by square footage?

Why it matters: Manual J is the industry-standard math that accounts for your home's insulation, windows, orientation, and air leakage. Square-footage rules of thumb routinely oversize equipment, and an oversized system short cycles, dehumidifies poorly, wears out faster, and costs more up front. This is the single most common installation error. A good answer: a room-by-room Manual J, with the report shared with you. If the term is new, our explainer on what Manual J is covers it in plain words.

2. Will you measure static pressure and inspect my ducts before quoting?

Why it matters: New equipment attached to leaky, undersized, or crushed ducts will underperform no matter what the brochure says. Static pressure is the blood-pressure test of your duct system, and measuring it takes minutes. A good answer: yes, with readings shown to you, and duct repairs quoted separately if needed. Our glossary entry on static pressure explains the measurement, and our duct replacement calculator can give you a feel for what duct work involves before the visit.

3. How did you choose the equipment you are quoting?

Why it matters: The right answer connects the Manual J result, your ducts, your electrical panel, and your goals. The wrong answer is that it is the model on this month's promotion. A good answer: a reasoned match between the load calculation and the equipment's actual capacity at Puget Sound design temperatures, including cold-weather performance for heat pumps. Since the 2021 heat dome, cooling capacity matters here too, and a careful installer will size for both seasons rather than one.

Paperwork, permits, and people

4. Who files the rebate paperwork?

Why it matters: Between utility rebates, the Washington HEAR program, and the federal 25C tax credit, real money is on the table for efficient equipment, and the paperwork has deadlines and documentation requirements. A good answer: the contractor files utility rebates directly and hands you the documentation needed for tax credits. Ask early, because some rebates require pre-approval or a participating contractor. Our rebates page lists what is currently available in the region.

5. Will you pull the mechanical permit, and the electrical permit if needed?

Why it matters: Heat pump and furnace installs need mechanical permits, and many need electrical work too. Both should run under the installing company's licenses. A good answer: yes to both, with fees itemized in the bid. A company that treats permits as optional is showing you its quality floor.

6. What brand certifications do your installers hold?

Why it matters: Manufacturer certification programs mean trained installers, access to technical support, and sometimes extended warranties. It also signals the company can actually get parts when something fails in year six. A good answer: named certifications for the brands being quoted, not a vague claim that the techs are factory trained.

7. Are the installers employees or subcontractors?

Why it matters: Neither is automatically bad, but accountability differs. If a sub does the work, whose warranty applies and whose insurance responds? A good answer: a direct statement of who does the work and confirmation that warranty and insurance sit with the company you are paying.

Warranty, commissioning, and follow-through

8. What maintenance does the manufacturer warranty require, and what records should I keep?

Why it matters: Most equipment warranties require regular professional maintenance, and manufacturers can deny claims when there are no records. This surprises homeowners constantly. A good answer: a plain list of required service intervals, what each visit includes, and a recommendation to keep dated invoices. Our seasonal tune-up page describes what a proper maintenance visit covers.

9. How will you commission the system on install day?

Why it matters: Commissioning means verifying refrigerant charge, airflow, electrical draw, and controls against specifications instead of just confirming that air comes out. Skipped commissioning is why identical equipment performs differently in different houses. A good answer: a specific checklist, with the measurements recorded and left with you.

10. What is the labor warranty, separate from the parts warranty?

Why it matters: Manufacturers cover parts, often for ten years with registration. Labor to diagnose and replace those parts is the contractor's warranty, and it varies wildly. A good answer: a specific labor term, in writing, with any conditions stated up front.

11. What happens if the system does not perform as promised?

Why it matters: A confident installer will stand behind measurable outcomes: target temperatures at design conditions, sound levels, humidity. A good answer: a commitment to return, diagnose, and correct at no charge if the system misses the design targets they set.

12. What exactly is included in the price?

Why it matters: Pads, disconnects, line sets, condensate handling, thermostats, duct transitions, and haul-away are where cheap bids quietly cut. A good answer: an itemized scope you can put next to the other bids, line by line. Compare scopes first, totals second. A bid that is thousands lower almost always differs in what it leaves out, not in how efficiently the company works, and the missing items come back as change orders later.

Common questions

Is bigger equipment safer than smaller equipment?

No. Oversized systems cycle on and off rapidly, which wears components, leaves rooms clammy in summer, and creates uneven temperatures. The goal is matching the load calculation, not adding a size for comfort. If a bidder proposes a larger unit than the Manual J supports, ask them to show their math.

Do I need new ducts every time I replace the equipment?

No, and be wary of anyone who says so without measuring. The honest sequence is test first, then decide. Some duct systems need sealing, some need a few runs corrected, and some genuinely need replacement. The static pressure reading and a visual inspection tell the story.

How long should a heat pump or furnace install take?

Most straightforward replacements run one to two days, and jobs that add ductwork, electrical upgrades, or a new refrigerant line set can take longer. A changeout finished in three hours with no commissioning measurements is a red flag, not a bonus. Ask to see the startup readings before the crew leaves, and keep them with your warranty paperwork.

What to do next

Ask every HVAC bidder these twelve questions and insist on seeing the Manual J and static pressure numbers, not just hearing that they were done. If you want a bid built that way, Eco publishes its process and performs the calculation on every system we quote. Start on our heat pump page, book online, or call (206) 970-1031, 6 AM to 6 PM every day.