How to How to Replace a Thermostat
Upgrading to a programmable or smart thermostat saves 10-30% on heating and cooling costs. Learn to replace your old thermostat in under an hour.
Your Progress
0 of 6 steps completedStep-by-Step Instructions
1 Step 1: Choose Compatible Thermostat
Mike Johnson: "Pro tip: Make sure to double-check this before moving to the next step..."
Step 1: Choose Compatible Thermostat
Check your HVAC system compatibility: number of wires (most homes have 4-8), voltage (most are 24V low voltage), and system type (gas, electric, heat pump). Take photo of existing wiring before buying.
Google Nest Learning Thermostat
Premium smart thermostat, learns schedule, works with most systems
2 Step 2: Turn Off Power
Mike Johnson: "Pro tip: Make sure to double-check this before moving to the next step..."
Step 2: Turn Off Power
Turn off breaker for HVAC system (usually labeled "furnace" or "AC"). Don't just turn off thermostat - must kill power at breaker. Most thermostats are low voltage (24V) but best practice is breaker off.
3 Step 3: Remove Old Thermostat
Mike Johnson: "Pro tip: Make sure to double-check this before moving to the next step..."
Step 3: Remove Old Thermostat
Take clear photo of wiring showing which wire goes to which terminal letter (R, W, Y, G, C, etc). Label each wire with tape and marker. Remove wires carefully. Remove old mounting plate from wall.
4 Step 4: Install New Mounting Plate
Step 4: Install New Mounting Plate
Feed wires through new plate opening. Level plate on wall using bubble level. Mark screw holes. Drill pilot holes if needed. Secure plate with included screws. Don't overtighten drywall anchors.
5 Step 5: Connect Wires to New Thermostat
Step 5: Connect Wires to New Thermostat
Match wire labels to new terminals: R (red/power), W (white/heat), Y (yellow/cooling), G (green/fan), C (blue or black/common - needed for smart thermostats). Push wires in firmly until they click.
6 Step 6: Attach Thermostat and Configure
Step 6: Attach Thermostat and Configure
Snap thermostat onto mounting plate. Turn power back on. Follow setup prompts: WiFi connection (if smart), system type, heating/cooling stages, schedule. Test: turn heat to 85°F, verify furnace starts. Turn to 60°F, verify it stops.