Replacing a furnace, AC, or heat pump is one of the largest home purchases most people make, and the quality of the installer matters more than the brand of equipment. A correctly sized, correctly installed mid-tier system will outperform a premium unit that’s oversized and short on refrigerant. This page is how to tell the two apart before you sign.
The short version: get at least three quotes, confirm the license and insurance yourself, insist on a Manual J load calculation, and read the warranty for both parts and labor. The questions and red flags below are what separate a company that does it right from one that installs by rule of thumb.
Types of HVAC companies, and what to look for
Not every company is set up for every job. Knowing the category tells you what to expect.
- Independent local shops. Owner-operated or small crews. Often the best value and the most accountable, because their reputation is local and they’ll be the ones servicing the system for years. Look for a stable business address, years in business, and a real service department (not just install-and-disappear).
- Regional and franchise companies. Bigger marketing, more trucks, structured warranties and financing. Can be excellent, but pricing runs higher to cover overhead, and the salesperson who quotes you is often not the tech who installs. Ask who actually does the load calc and the install.
- Big-box and retailer installers (home-improvement stores, warehouse clubs). Convenient, with brand-name backing, but the install is usually subcontracted to a third party. The store’s name is on the sale; a different company is on your roof. Vet the subcontractor, not just the retailer.
- Manufacturer-certified dealers (Carrier, Trane, Lennox, Bosch, Mitsubishi, etc.). Factory training and access to the best manufacturer warranties, which frequently require certified installation to stay valid. Worth prioritizing for heat pumps and inverter systems, where install quality decides real-world performance.
- Online-first / “instant quote” companies. Fast and transparent on price, but confirm who performs the in-home load calculation. A quote generated from your square footage alone, with no one measuring your home, is a rule-of-thumb estimate, not a design.
Whatever the category, the vetting below is the same.
Before you get a quote: insist on system sizing
The single most common installation mistake is an oversized system. A unit that’s too big short-cycles: it blasts to temperature, shuts off, and never runs long enough to pull humidity out of the air or let a heat pump’s inverter settle into its efficient range. The result is a house that’s clammy, a compressor that wears out early, and a bill higher than it should be. Industry estimates put a large share of residential systems significantly oversized.
The fix is a Manual J load calculation: the ACCA-standard method for computing how much heating and cooling your specific home actually needs, room by room, based on insulation, windows, orientation, and air leakage. It’s accurate to within about 10–15%. “One ton per 400–600 square feet” is not; it can miss by half.
What to ask for: a written Manual J report, and equipment sized to roughly 95–115% of the calculated load (that’s the companion ACCA Manual S selection standard). If a contractor sizes your system by square footage or by “what’s in there now,” that’s your first red flag. A good report lists room-by-room loads, the design temperatures used, envelope assumptions, and the recommended capacity range.
The questions to ask every contractor
Ask all of these before you sign. The quality of the answer matters as much as the answer itself.
- Did you perform a Manual J load calculation, and can I see it? Good: a written room-by-room report. Bad: “I’ve done a thousand of these, I know what you need.”
- What exact model are you installing, and why that one? You want a model number, not “a 3-ton unit.” Vague equipment lets a contractor substitute something cheaper later.
- What’s the efficiency rating (SEER2 / HSPF2) of that specific model?
- Is the compressor single-stage, two-stage, or variable-speed? This drives comfort and efficiency, and should match the sizing.
- What refrigerant does it use? As of 2025 the industry moved to low-GWP refrigerants (R-454B, R-32). Ask, so you’re not buying a system that’s already being phased out.
- What electrical work is included? Heat pumps often need a new circuit or a panel evaluation. This is where surprise costs hide.
- What’s included, itemized? A single “everything included” number with no breakdown makes it impossible to compare bids.
- Who pulls the permit, you or me? The contractor should. If they ask you to pull it, they may not be licensed for the work.
- What heating capacity will this deliver at our local design temperature? Especially for heat pumps in cold climates, because capacity drops as it gets colder, and you need to know the backup-heat plan.
- **What’s the warranty, manufacturer and your labor?** See the next section.
- How long have you been installing this type of system specifically? A veteran furnace installer may have limited heat-pump hours. Ask for the heat-pump-specific track record, not just “years in business.”
- Can you provide references from similar recent installs?
- What’s the plan for backup or emergency heat?
- How will you handle the existing gas line / old equipment removal?
Warranty: read both halves
Two separate warranties cover your system, and contractors sometimes blur them:
- Manufacturer warranty covers the equipment, typically 10 years on parts, and often only if a certified installer registers it and the install passes inspection. Ask whether registration is included.
- Labor warranty comes from the contractor and covers the work, commonly 1 to 5 years. This is the one that varies most and tells you the most. A strong answer sounds like “10-year manufacturer parts, plus 2 years labor from us, in writing.” A weak answer is vague, verbal, or labor-free.
A “satisfaction guarantee” is marketing, not a warranty. Get the actual terms on paper.
Verify the license, insurance, and bond yourself
Don’t take a logo on a truck as proof. Every state licenses HVAC work differently, so check with your state’s contractor licensing board (in California, for example, that’s the CSLB at cslb.ca.gov). Confirm:
- The license is active and covers HVAC work (many states use a dedicated mechanical/HVAC classification; larger heat-pump jobs adding circuits may also require a licensed electrician).
- Workers’ compensation and liability insurance are current. This protects you if someone is hurt on your property.
- A surety bond is in place (many states set a minimum).
- No pattern of unresolved complaints, and the business name matches the one on your quote.
Two credentials worth asking about on top of the license: EPA Section 608 certification (federally required to handle refrigerant) and NATE certification (not legally required, but the industry’s standard mark of a well-trained tech).
Red flags in a quote
Any one of these is a reason to slow down. Several together is a reason to walk away.
- No Manual J (sizing by rule of thumb).
- Equipment model left unspecified.
- One lump sum with no itemization.
- A bid more than ~30% below the others, which usually means something’s missing (permit, electrical, or lower-grade equipment).
- They ask you to pull the permit.
- A cash or “no-permit” discount.
- Pressure to sign today.
- They can’t or won’t give a license number.
- No written warranty.
- They won’t name the refrigerant.
Don’t skip the permit
Most HVAC replacements require a permit, and often a separate electrical permit and a final inspection. In some jurisdictions, efficiency rules trigger third-party verification (in California, HERS testing). Skipping the permit can void your homeowner’s insurance, complicate a future home sale, and cost two to three times as much to permit retroactively. A contractor who treats the permit as optional is telling you something.
Get at least three quotes, then compare them honestly
Three bids is the floor; four or five is better. But comparing them is where most homeowners get stuck, because the quotes rarely line up: different equipment, different scope, different ways of describing the same work.
Compare bids without the guesswork: BidSmart
BidSmart is a free tool from Pandotic (the studio behind this site), built for exactly this step. You upload your contractor bids, tell it what you care about (price, efficiency, warranty, scope), and it returns a structured, side-by-side comparison, flags the gaps and red flags, and generates the specific questions to ask each contractor. It checks whether a bid includes a Manual J, whether the equipment is sized within range, and how the warranties and scope actually compare, grounded in the specs from your documents.
It’s a neutral analysis tool: BidSmart does not endorse specific contractors or manufacturers, and it isn’t a substitute for professional advice. For project-specific guidance, consult a licensed professional. It just makes three confusing PDFs comparable.
Analyze your HVAC bids with BidSmart →
Where to find local HVAC pros
These directories help you build your shortlist of companies to get quotes from. Start with the ACCA locator, which is the industry association’s own list, weighted toward contractors who commit to quality-installation standards rather than a pay-to-play lead marketplace.
| Directory | Best for | Link |
|---|---|---|
| ACCA Find a Contractor | Quality-focused, industry-vetted installers | hvac-contractors.acca.org/locator |
| Angi | Broad coverage, homeowner reviews | angi.com/nearme/hvac |
| Houzz | Reviews plus project photos | houzz.com/professionals/hvac-contractors |
| Yelp | Local reviews and quick reputation check | yelp.com HVAC search |
| Manufacturer dealer locators | Factory-certified installs + best warranties | Carrier, Trane, Lennox, Bosch, and Mitsubishi each list certified local dealers on their own sites |
These are here because they’re useful. We don’t currently earn a commission from any of them; if that changes, we’ll say so on this page.
Where this fits
If you’re still deciding what to install, start with our buying guides: Best Thermostat for a Heat Pump, Nest vs ecobee. Replacing an older system and doing part of the work yourself? Thermostat wiring color codes covers the control-side swap, and Aux heat vs emergency heat explains the heat-pump backup wiring a contractor will set up. Planning the whole-home energy picture, not just the equipment? Our sister site covers cold-climate heat pump selection.
Frequently asked questions
How many HVAC quotes should I get? At least three, ideally four or five. Multiple bids reveal when one is missing scope (like a permit or electrical work) or when the pricing is out of line in either direction.
What is a Manual J and why does it matter? Manual J is the ACCA-standard load calculation that determines how much heating and cooling your specific home needs. It prevents oversizing, which causes short-cycling, poor humidity control, and early compressor wear. If a contractor can’t provide one, they’re sizing by rule of thumb.
What HVAC warranty is normal? Typically 10 years on manufacturer parts (often requiring certified installation and registration), plus a separate contractor labor warranty of 1 to 5 years. Get both in writing.
How do I check if an HVAC contractor is licensed? Look them up on your state’s contractor licensing board and confirm the license is active, covers HVAC work, and has current workers’ comp and liability insurance plus any required bond. Also ask about EPA Section 608 certification for refrigerant handling.
Do I need a permit to replace my HVAC system? In most places, yes. Usually a mechanical permit, sometimes a separate electrical permit, and a final inspection. Skipping it can void insurance and complicate a home sale. The contractor should pull the permit, not you.
Should I just buy the biggest system I can afford? No. Bigger is worse if it’s oversized for your home. A right-sized system runs longer, cheaper, and more comfortably. Size to the Manual J load, not to square footage or to “what was there before.”
