Maintain temperature using a room heater
In colder rooms, add supplemental heating to maintain comfortable temperature automatically. Perfect for rooms that stay consistently cold or need different temperatures than the rest of the house.
Use cases
Bedrooms & Living
- Cold Bedroom - Room gets too cold during the night
- Kids' Room Warmer - Children want warmer bedroom than rest of house
- Guest Room - Maintain comfortable temperature only when occupied
Workspaces
- Garage Office - Converted workspace needs extra heat
- Basement Room - Lower levels stay consistently cold
Products needed
Essential Equipment
Accurate temperature • Fast updates • Good battery life
UL, ETL, or CE certified • Tip-over protection • Overheat protection
Must handle 1500W heater • Power monitoring recommended
Optional Enhancements
Basic automation setup
- Never operate heater with window open
- Use only certified heaters (UL, ETL, CE)
- Ensure 3 feet clearance on all sides
- Implement maximum runtime shutoff (8 hours)
- Always check window sensor in conditions
Part 1: Turn On When Cold
Trigger: Room temperature drops below 68°F (20°C)Conditions: Window is closed (CRITICAL) • Time between 6 PM - 8 AM
Action: Turn on smart plug with room heater
Part 2: Turn Off When Warm
Trigger: Room temperature rises above 70°F (21°C)Conditions: None (always turn off when warm enough)
Action: Turn off smart plug with room heater
Platform-specific examples
Home Assistant
SmartThings
Hubitat
Apple HomeKit
Alexa
Google Home
Advanced features
Presence-based heating
Only run heater when room is occupied:
Create automation with these elements:
- Trigger: Bedroom temperature below 68°F
- Conditions:
- Window is closed
- Room is occupied (motion sensor active OR presence sensor detects person)
- Action: Turn on heater
Pre-warm before bedtime
Start heating room before typical bedtime:
Create automation with these elements:
- Trigger: Time is 9:00 PM
- Conditions:
- Bedroom temperature below 68°F
- Window is closed
- Action: Turn on heater
Smart scheduling
Different temperatures for different times:
Create automation triggered by temperature change:
- Bedtime (10 PM - 7 AM): Keep warm 68-70°F
- If temp below 68°F AND window closed: Turn on heater
- When warm enough (above 70°F): Turn off heater
Use conditional logic based on time of day and current temperature.
Power failure recovery
Don’t automatically restart heater after power outage:
Create automation triggered when system starts/restarts:
- Action: Turn off heater smart plug (ensures safe state after power restoration)
Safety considerations
⚠️ Critical Safety Rules
1. Never operate heater with window open
- Risk of carbon monoxide (for fuel-based heaters)
- Massive energy waste
- Always check window sensor in automation conditions
2. Use certified heaters only
- Look for UL, ETL, or CE certification
- Must have tip-over protection
- Must have overheat protection
- Avoid old or damaged heaters
3. Don’t cover heater
- Ensure 3 feet clearance on all sides
- Never place under desks or in closets
- Keep away from curtains, bedding, furniture
4. Monitor for faults
- Send alert if heater runs more than 8 hours continuously
- Track power consumption to detect issues
- Stop automation if unusual behavior detected
5. Power monitoring recommended
- Track watts to detect issues (normal: 1500W, problem: significantly different)
- Alert if power consumption abnormal
- Automatic shutoff if power exceeds safe levels
Recommended safety automations
Window open safety: Create emergency shutoff automation:
- Trigger: Bedroom window opens
- Condition: Heater is currently on
- Actions:
- Turn off heater immediately
- Send safety alert notification: “SAFETY: Heater turned off - window opened”
Maximum Runtime: Always implement maximum runtime shutoff (shown in examples above).
Away Mode: Turn off all heaters when house is in Away mode.
Troubleshooting
Issue: Room never reaches target temperature
Causes:
- Heater undersized for room
- Room has poor insulation
- Outdoor temperature extremely cold
- Heater on smart plug that can’t supply enough power
- Temperature sensor placement incorrect
Solutions: ✅ Calculate room heating requirements (typically 10W per sq ft) ✅ Check heater wattage matches or exceeds room needs ✅ Verify smart plug rated for heater wattage (usually need 15A/1800W capacity) ✅ Improve room insulation (door draft stopper, window sealing) ✅ Lower target temperature expectations in extreme cold ✅ Move temperature sensor away from heater, windows, doors ✅ Consider larger heater or multiple heaters
Issue: Heater cycles on/off too frequently
Causes:
- Temperature thresholds too close together (68°F off, 69°F on)
- Temperature sensor too close to heater
- Rapid temperature fluctuations in room
- No delay in automation triggers
Check:
- ✅ Increase temperature deadband (66°F on, 70°F off = 4° difference)
- ✅ Move sensor away from heater - at least 6-10 feet
- ✅ Add “for: 5 minutes” delay to both on and off triggers
- ✅ Use slower-responding sensor position (avoid direct airflow)
Fix: Modify trigger with:
- Lower threshold: Turn on at 66°F instead of 68°F
- Add 5 minute delay: Temperature must stay below threshold for 5 minutes before turning on
Issue: Smart plug turns off unexpectedly
Causes:
- Smart plug overheating
- Heater drawing too much power
- Smart plug not rated for heater
- Network connectivity issues
- Automation or safety feature triggering
Solutions: ✅ Verify smart plug specifications: Must support 15A / 1500-1800W ✅ Check for overheating: Touch plug after running - should be warm not hot ✅ Use in-wall smart outlet instead of plug (better heat dissipation) ✅ Review automation logs: Check what turned off the plug ✅ Check heater actual wattage (use kill-a-watt meter) ✅ Don’t daisy-chain plugs or use extension cords ✅ Replace smart plug if overheating or failing
Related automations: