Heating system installation in Cottleville, MO, typically starts with an in-home assessment and load calculation, followed by removing the old furnace, setting the new unit, connecting ductwork, gas, and electrical lines, then testing the system. Most jobs finish in a single day, though permits and inspections can add time. If your old system has needed frequent heating system repairs, replacement day usually goes smoother than expected. As Air Alliance Team, we walk homeowners through every step, from the first estimate to the final walkthrough.
How Does Furnace Installation Start?
Before any equipment arrives, an Air Alliance Team technician visits the home to measure square footage, check insulation, and calculate the correct furnace size using a load calculation. Skipping this step is a common mistake: installing a furnace based on the old unit’s size, rather than a fresh calculation, can leave a home with uneven heating or higher bills. This visit is also when the technician confirms whether a mechanical permit is needed, since most Missouri municipalities require one for new furnace installations.
What Happens on Installation Day?
A typical installation follows this sequence:
- Disconnecting and removing the old furnace
- Preparing the installation area and checking existing ductwork
- Positioning and leveling the new furnace
- Connecting ductwork, electrical wiring, and gas or fuel lines
- Installing or updating the thermostat
- Testing ignition, airflow, and safety controls
- Walking the homeowner through the new system’s operation
How Long Does Furnace Installation Take?
Timing depends on the fuel type and whether ductwork needs changes.
| Installation Type | Typical Time |
| Gas furnace, existing ductwork reused | 6 to 10 hours |
| Electric furnace, existing ductwork reused | 4 to 6 hours |
| Any furnace type, ductwork modifications needed | Full day or longer |
On average, a professional furnace installation takes 4 to 10 hours, according to Lennox. Straightforward replacements finish closer to the low end, while jobs involving new ductwork or electrical upgrades run longer.
Does Cottleville Require a Permit for Furnace Installation?
Yes. Furnace installations fall under the mechanical permit category in St. Charles County, and at least one inspection is required before the job is signed off, according to the St. Charles County Building and Code Enforcement Division. A licensed contractor handles the permit application and schedules the inspection as part of the installation process, so homeowners don’t have to manage that paperwork themselves.
Frequently Asked Questions
Do I need to be home during the entire heating system installation?
Homeowners typically need to be available at the start for a walkthrough and at the end to review the completed system, but don’t need to be present for every step in between.
Will I be without heat during the installation?
Most installations are completed in a single day, so a home is usually without heat for only a few hours during the swap.
What should I do after the heating system installation is finished?
Ask about warranty registration and schedule the first round of heating system services for the following fall to keep the new equipment running efficiently.
Ready to Get Started?
Air Alliance Team has handled heating system installation in Cottleville, MO, for over 35 years, and we’re a Lennox Premier Dealer, so homeowners get factory-trained expertise on installation day. If your current furnace is due for heating system repairs more often than not, our team can walk you through your replacement options. Call us at (636) 294-2777 or email info@airallianceteam.com to schedule your installation estimate.
