CMCORKY'S MHS™ Corky's Corner™

Trade guide

HVAC (Heating & Cooling)

Furnaces, central air, heat pumps, ductless mini-splits, ductwork and thermostats. Correct sizing and duct design matter as much as the brand.

Run the calculator for this: HVACRun the calculator for this: HVAC or Evaporative Cooler ReplacementGet a Second Look Review
Checkmarks are saved only in this browser.

What the work involves

  • Load calculation to size equipment
  • Removing old equipment and recovering refrigerant
  • Installing equipment, line sets, drains and controls
  • Duct repair, sealing or replacement
  • Startup, testing and explaining maintenance

What should happen, step by step

Use this as a checklist while the job is underway. If a step is skipped, ask why.

Durations are typical planning ranges from Corky's field experience, not guarantees. Weather, inspections, material lead times and surprises behind walls change them.

How long it usually takes

Replacing equipment with similar equipment is often a one- to two-day job. New ductwork or a system type change takes longer. Equipment availability can affect scheduling.

Plan your dates with the Project Timeline Planner

General guidance only. Your contractor's written schedule is what counts.

Inspections to expect

  • Mechanical permit final inspection
  • Electrical and gas inspections where circuits or gas lines change

Which inspections apply depends on your city or county. Ask your contractor to share each passed inspection result. Understanding permits & inspections

What a good bid includes

Check off each item on the bids you receive:

How to read a bid · Have one in hand? Second Look Review (from $25)

Payment schedule

Deposit, balance on completion and start-up; for large duct jobs, a mid-point payment.

  • Pay a modest deposit, then progress payments tied to finished, visible milestones (e.g., 'rough-in passed inspection'), never to dates alone.
  • Keep payments at or behind the work completed - you should never have paid for much more than has been done and delivered.
  • Hold the final payment until the final inspection is passed, the punch list is finished and you have lien waivers.
  • Avoid cash. Pay by check or card so there is a record, and get a receipt for every payment.
  • Deposit limits vary by state: California, for example, caps a home improvement down payment at 10% of the price or $1,000, whichever is less. Arizona has no single statewide percentage cap that we are aware of, so negotiate it and put it in the contract. Check your state's rules.

Payment schedules & lien waivers

Red flags & common rip-offs

  • Sizing by square foot 'rule of thumb' instead of a load calculation
  • Scare tactics about carbon monoxide without showing test results
  • Pushing duct cleaning as a cure-all
  • No permit
  • Warranty that depends on registration they don't do
  • No start-up readings left with you
  • Oversized equipment 'to be safe'

Also watch for the general warning signs: large upfront payments, cash-only, no written estimate, pressure to sign today and no proof of license or insurance.

Questions to ask before you sign

  1. Did you do a load calculation? Can I see it?
  2. What is the exact model and efficiency rating?
  3. Will you check and seal ductwork?
  4. Are electrical changes included?
  5. Who registers the warranty and what does labor coverage include?
  6. What airflow and refrigerant charge readings will you record at start-up?
  7. In our desert climate, is the equipment rated for high outdoor temperatures?

Get the answers in writing, in the contract. Always ask for the contractor's license number and proof of insurance, and check the license with your state or local licensing agency. How to hire a contractor · Quick question? Contractor's Desk ($5)

Warranty

Equipment makers often offer longer parts warranties when registered. Labor warranties vary by contractor.

Expect two kinds of warranty: the manufacturer's product warranty (shingles, windows, fixtures, equipment) and the contractor's workmanship warranty on the installation. Get both in writing with the length, what is covered and how to make a claim. Many product warranties require registration or installation per the manufacturer's instructions. In Arizona, a homeowner can file a workmanship complaint against a licensed contractor with the Registrar of Contractors within two years of the last work performed on a remodel or repair.

DIY vs. hire out

Usually OK to DIY

  • Changing filters
  • Keeping the outdoor unit clear
  • Cleaning supply registers

Hire a licensed pro

  • Refrigerant work (federally regulated)
  • Gas, electrical and duct changes
  • Equipment replacement

Some work legally requires a licensed contractor and a permit even on your own home. Check your state and city rules.

Permits to expect

HVAC equipment replacement usually requires a mechanical permit; gas and electrical work may be inspected too. Refrigerant handling is federally regulated. Permit rules are set by your city, county and state, so they vary a lot. Call or check the website of your local building department before work starts. When a permit is required, the licensed contractor usually pulls it in their own name.

General information, not legal advice. Requirements vary by location.

Sources

Check a contractor license: search your state's contractor licensing board, or find your state consumer protection office. External sites open in a new tab; Corky's MHS™ is not affiliated with them.

Please note

Educational information only - not legal, engineering or code advice. Rules vary by state, county and city, and change over time. Check with your local building department and licensing board, and read your own contract.