Hiring a furnace installer

Equipment is half the price. Installation quality is what determines whether the furnace runs efficiently for 18 years or breaks down in 10. The contractor matters as much as the brand. Here is how to vet, what the quote should show, and the red flags to walk away from.

Get 3+ quotes with the brand, model number, AFUE, and BTU spelled out. Verify the contractor is licensed, insured, NATE-certified, and pulls the permit. Walk away from any contractor who pressures you to sign today, sizes by square footage alone, or quotes without an in-person inspection.

Seven things to verify

State HVAC license

Required in 36 states. Search your state's licensing board database. Check for current status and any complaints filed.

NATE certification

North American Technician Excellence. Industry-standard competency test for HVAC techs. Not a hiring requirement but a strong signal.

EPA 608 universal

Mandatory for any refrigerant work. Required if your job includes AC or you're considering a heat pump.

Liability insurance

$1M minimum general liability. Ask for a certificate. If they cannot provide one in 24 hours, they probably do not have it.

Workers compensation

Protects you if a tech is injured on your property. Without it, you can be liable. Required in nearly every state.

Years in business

5+ years preferred. Search your state's secretary of state for the entity registration date.

Reviews

Google (most reliable), BBB (good for complaint resolution patterns). Ignore Yelp HVAC reviews, heavily filtered. 50+ reviews with 4.5+ stars is a healthy signal.

What the quote must include

A quote without these items is incomplete and impossible to compare to other quotes:

✓Brand, model number, AFUE, BTU

✓Stage type (single, two-stage, variable)

✓Equipment cost itemised

✓Labour estimate (hours and rate)

✓Permit fee and confirmation contractor pulls it

✓Old unit removal and disposal

✓Any ductwork or gas line work itemised

✓Manufacturer warranty and registration

✓Labour warranty (1-2 years standard)

✓Payment schedule (no more than 50% deposit)

✓Start and completion dates

✓Manual J load calc included or itemised

Red flags to walk away from

×Pressure to decide today ("this price is only good if you sign now")
×Cash-only or wire transfer payment
×Suggests skipping the permit to save money
×No written contract, only verbal agreements
×Sizes the furnace by square footage alone, no Manual J load calc
×Quotes without inspecting the existing system in person
×Price 25%+ lower than two other quotes for the same model
×Vague brand or model, "a good 95% AFUE unit" is not a quote
×Demands more than 50% deposit before equipment arrives
×Cannot produce a current insurance certificate

Installation day

A standard furnace replacement takes 6 to 8 hours. A complex install with new gas line, ductwork modifications, or fuel conversion takes 10 to 14 hours. What a quality install looks like:

Drop cloths down, register covers in place. Crew arrives at the scheduled time.
Old unit disconnected (gas, electric, flue, condensate) and removed.
New furnace cabinet placed, plumb and level, secured to the platform.
Gas line connection (with leak test using soap solution), electrical hookup, condensate drain plumbed if condensing.
PVC venting installed (for 90%+ AFUE) or metal flue connected (for 80%).
Ductwork connections sealed with mastic or UL-listed tape.
Thermostat hooked up and configured. New units may need updated thermostat.
Combustion analysis with electronic analyser. CO levels checked. Gas pressure measured and adjusted.
Walkthrough: tech shows you the breaker, gas shutoff, condensate trap, filter location, and basic operation.
Permits closed out, manuals and warranty cards left with you, jobsite cleaned.

Post-installation

→Register the warranty within 60 to 90 days. Most manufacturers shorten the heat exchanger warranty from lifetime to 5 years if you do not register.
→Schedule annual maintenance. $150-$300 for a tune-up. Most contractors offer multi-year service plans.
→Change the filter every 1 to 3 months. Dirty filters drop airflow, drop efficiency, and stress the blower motor.
→Watch for the inspector. Most municipalities send a permit inspector within 30 days. Be available, they may want to see flue connections, gas line, and electrical.

Hiring FAQ

What certifications should a furnace installer have?+

State HVAC contractor license (required in 36 states for residential gas work). NATE certification (industry standard for technician competency). EPA 608 universal certification (required to handle refrigerants on combo furnace + AC jobs). Active general liability insurance ($1M minimum) and workers compensation. Manufacturer factory training for the brand they are installing.

How many quotes should I get for a furnace?+

Three is the minimum. Three quotes for the same brand and model number typically vary by 25 to 35% in price. Without three quotes you have no benchmark for what is reasonable in your market. With more than five quotes you hit diminishing returns and waste contractor time.

Should I trust the lowest quote?+

Not automatically. A quote that is 25%+ lower than two others usually signals one of three things: (1) the contractor is cutting a corner you cannot see (smaller crew, skipped permit, lower-AFUE swap), (2) they are using a no-name brand without parts support, or (3) they will up-sell on the day with surprise costs. Investigate the gap before signing.