where should i put the ecobee smart sensors for them to work right? my living room one seems wonky.

Diagnosis

The "wonky" readings you are experiencing with your ecobee SmartSensor are likely caused by "micro-climates" or sensor interference. The SmartSensor uses a thermistor for temperature and a Passive Infrared (PIR) sensor for occupancy. When placed incorrectly, the device registers temperature fluctuations that don't represent the actual living space, or it fails to trigger the occupancy state because of obstructed sightlines.

Common culprits include "ghost drafts" from nearby windows or "heat soaking" from electronics and lamps. If the sensor is placed on an exterior wall, the wall's own thermal mass can cool or heat the sensor independently of the air temperature. Furthermore, if the sensor is placed too low, it captures the cooler air that settles near the floor, leading the ecobee to over-heat the room to satisfy a sensor that is reading 2-3 degrees lower than the actual breathing zone.

How to Fix It

To optimize your ecobee SmartSensor Premium for both thermal accuracy and motion detection, follow these precise installation steps:

1. Identify the "Breathing Zone": Mount the sensor exactly 48 to 60 inches (4 to 5 feet) from the floor. This is the median height where humans actually experience the room's temperature.
2. Avoid Thermal Interference: Ensure the sensor is at least 3 feet away from any HVAC supply vents, return air grilles, radiators, or heat-generating appliances (like a gaming PC or a lamp).
3. Wall Selection: Place the sensor on an interior wall. Avoid exterior walls, as the temperature of the drywall will fluctuate based on the outdoor weather, skewing the sensor's reading.
4. Optimize Sightlines: Position the sensor facing the center of the room. The PIR sensor has a 140° horizontal and 100° vertical field of view. Ensure there are no curtains, large plants, or furniture blocking the direct line of sight to the areas where people typically move.
5. Secure Mounting: Use the included adhesive or the screw-mount bracket. Ensure the sensor is flush against the wall; a gap between the sensor and the wall can create a pocket of stagnant air that traps heat.

If That Didn't Work

If your readings remain inconsistent after relocation, try these advanced troubleshooting steps:

• Check Sensor Participation Settings: Open the ecobee app, go to the main thermostat screen, select the "Sensors" menu, and verify which sensors are participating in the current comfort setting (Home, Away, or Sleep). If you have multiple sensors, the ecobee averages the temperature. If one sensor is in a drafty hallway, it will pull the average down, making the living room feel too hot. Disable "participation" for sensors in non-critical areas.
• Calibrate via Offset: If the sensor is consistently off by a specific number of degrees compared to a handheld thermometer, you can apply a temperature offset in the advanced settings to align the digital reading with the actual room temperature.
• Test Battery Voltage: Replace the CR2032 battery. When batteries run low, the PIR motion sensor often fails before the temperature sensor does, leading to "wonky" occupancy behavior where the room is marked as empty despite people being present.
• Relocate for Pet Immunity: If you have large dogs or cats triggering the occupancy sensor, move the sensor higher up the wall (approximately 6.5 to 7 feet). This puts the pets below the PIR sensor's primary detection cone while still capturing human movement.

Heads Up

Keep these maintenance and operational tips in mind:

• Avoid Direct Sunlight: Never place a sensor where a sunbeam hits it during the day; the plastic casing will absorb radiant heat, causing the thermostat to think the room is 10 degrees warmer than it actually is.
• Dust Regularly: Use a can of compressed air to clean the PIR window on the front of the sensor. Dust buildup can degrade the motion detection sensitivity.
• Avoid "Dead Air" Corners: Do not tuck sensors behind sofas or inside bookshelves. These areas lack airflow and will provide a stagnant reading that doesn't reflect the rest of the room.
• Symmetry Matters: If you are using sensors to balance a multi-room zone, place them in the rooms that are hardest to heat or cool (the "problem rooms") rather than the easiest.