If you've never replaced a furnace and AC before, the install day feels like a black box. Two trucks show up. Strangers go in your basement. Eight hours later they hand you a thermostat and leave. What just happened?
Here's exactly what a full HVAC replacement looks like, hour by hour, so you know what to expect.
The day before
A good HVAC contractor calls or texts the day before to:
- Confirm arrival time
- Confirm equipment delivery
- Remind you to clear access to the furnace and AC condenser
- Confirm payment and financing details
If your installer doesn't do this, that's a small red flag. The 8am call should not be the first communication of the week.
Day 1, 8:00 AM — Arrival and setup
The crew arrives — usually 2-3 technicians on a residential install. They:
- Walk the property with you
- Confirm equipment locations
- Lay drop cloths from the door to the furnace
- Set up tools and the new equipment
This is the time to ask questions. "Where's the new thermostat going? What's the runtime on this install? Who's the lead tech I should call if I have a question?"
8:30 AM — Old system removal
Refrigerant is recovered from the old AC (this is required by EPA — no contractor should be venting refrigerant). Then the old furnace, coil, and AC condenser come out. On most Cincinnati basement installs this takes 1-2 hours.
10:30 AM — New equipment in place
The new furnace is set, leveled, and connected to gas (if applicable), electric, and the existing ductwork. The new AC condenser is set on the existing pad outside (or a new pad if needed). The new evaporator coil is set on top of the furnace inside the supply plenum.
12:00 PM — Refrigerant lines and electrical
Old copper refrigerant lines are usually replaced (especially if going from R-22 to R-410A or the new R-454B). Electrical disconnects are updated. Thermostat wiring is run to the new smart thermostat.
1:30 PM — Vacuum and refrigerant charge
This is the most important step in any HVAC install. The refrigerant lines are pulled into a deep vacuum (under 500 microns) and held to make sure there are no leaks. Then the system is charged with refrigerant to manufacturer spec.
Skipping or rushing this step is the #1 reason new HVAC systems fail in year 2-3. A good Cincinnati installer will not cut corners here.
3:00 PM — Commissioning and testing
The system is fired up. The tech measures:
- Static pressure in the ductwork
- Supply and return temperatures
- Refrigerant subcooling and superheat
- Gas pressure (on furnaces)
- Amp draws on the compressor and blower
These numbers go on a commissioning sheet. Always ask for a copy. A real install includes documented startup numbers, not just "it's running."
4:00 PM — Walkthrough
The lead tech walks you through:
- The new thermostat (basic operation, scheduling, app pairing)
- The filter location and replacement schedule
- The warranty paperwork
- What to do if the system doesn't restart after a power outage
- What service intervals to expect
5:00 PM — Cleanup and signoff
Drop cloths come up. Old equipment leaves with the truck. The crew vacuums, signs the paperwork, and you do a final walkthrough. A good install leaves the basement cleaner than they found it.
What can extend a one-day install to two
- Older homes with non-standard ductwork that needs transitions
- Switching efficiency tiers (80% to 95% requires new venting through PVC)
- Code upgrades (old wiring, old gas line, etc.) that the inspector requires
- Attic or crawl space installs vs basement
- Adding a humidifier, UV system, or zoning during the same visit
Most Cincinnati replacements are still single-day jobs. Two-day jobs are usually known in advance and quoted that way.
How Gerard handles install day
Same crew start to finish. No subcontractors. Lead tech stays on site the entire day. Commissioning sheet provided. 12-year warranty paperwork in hand before the truck leaves. We've been doing this in Cincinnati basements for years.