Winter HVAC Preparation Checklist

When the first cold snap arrives, the last thing you want is a heating system that will not start. Preparing your HVAC system before cold weather ensures reliable performance, prevents costly emergency repairs, and keeps your energy bills manageable.

Schedule a Professional Furnace Inspection

A qualified HVAC technician should inspect your furnace annually. This tune-up typically includes cleaning the burners and heat exchanger, checking gas pressure and combustion efficiency, testing the ignition system, inspecting the flue pipe, verifying thermostat operation, checking electrical connections, lubricating blower motor bearings, and testing safety controls.

Schedule this appointment in early fall before HVAC companies get overwhelmed with emergency calls.

Replace the Air Filter

Start the heating season with a clean filter. Choose the MERV rating recommended for your system — typically MERV 8 to 11 for residential furnaces. The Filtrete 1500 MPR Smart Air Filter is a well-priced MERV 12 option that works in most standard residential furnaces.

Test the Heating System

Before you need heat, turn your thermostat to heating mode and set it a few degrees above room temperature. Listen for unusual sounds and verify that warm air is coming from all supply registers. Let the system run for at least 15 minutes.

Check Carbon Monoxide Detectors

Install CO detectors on every level and near sleeping areas
Replace batteries annually or install 10-year sealed battery models — the Google Nest Protect Smoke and CO Alarm is a sealed-battery model that also sends phone alerts
Test each detector by pressing the test button
Replace any detector more than 7 years old

Inspect and Seal Ductwork

Inspect accessible ductwork for disconnected joints, visible gaps at seams, crushed sections, and peeling duct tape. Professional duct sealing may be worthwhile if ducts are largely inaccessible or you notice significant temperature differences between rooms.

Prepare the Outdoor Unit

For heat pumps providing winter heating:

Remove debris from around the unit
Gently hose down the coils
Ensure the unit sits level
Verify defrost control is functioning
Do not cover the unit — it needs unrestricted airflow

For central AC units sitting idle, you may cover the top with a breathable cover. Do not wrap tightly in plastic.

Thermostat Setup

Set the fan to “auto” for heating season. A Google Nest Learning Thermostat learns your preferred temperatures automatically after a few days and optimizes the schedule as seasons change. Program a heating schedule:

Home and awake: 68 to 70 degrees
Sleeping: 60 to 65 degrees
Away at work: 60 to 62 degrees

Every degree you lower the thermostat saves approximately 1 to 3 percent on your heating bill.

Insulation and Air Sealing

Attic Insulation

The Department of Energy recommends R-38 to R-60 for attics. If you can see the ceiling joists, you likely need more insulation.

Weatherstripping and Caulking

Inspect seals around exterior doors and windows. Replace worn weatherstripping and apply fresh caulk where gaps are visible.

Pipe Insulation

Insulate exposed pipes in unheated areas like the attic, crawl space, and garage.

Humidifier Preparation

Replace the humidifier pad or evaporator panel
Open the bypass damper
Set humidity to 30 to 40 percent
Check the water supply line for leaks

Proper humidity improves comfort and can make 68 degrees feel warmer, allowing you to lower the thermostat slightly.

Emergency Preparedness

Stock extra furnace filters
Know how to shut off gas and water supplies
Keep flashlights, batteries, and blankets accessible
Have a portable space heater as backup
Program your HVAC company’s emergency number into your phone

Following this checklist each year keeps your heating system running efficiently and extends its service life.

Carbon Monoxide and HVAC Safety — the CO detector checks in this list are critical; this article explains why in detail
HVAC Filter Guide: Types and Replacement Schedules — choose the right filter for your heating system before winter
How to Lower Your Heating Bill — complement your preparation steps with strategies that reduce heating costs all season
Signs It Is Time to Replace Your Furnace — if your furnace fails its pre-season test, this guide helps you decide whether to repair or replace