Temperature Sensors for HVAC: Wall, Duct & Room Types Explained
Every control loop in an HVAC system starts with a temperature reading from somewhere — a room, a duct, a coil, or outdoors. Getting sensor placement and format right is what makes the rest of the control strategy actually work. Jaideo Automation supplies temperature sensors including the HSH-D Series Duct Temperature & Humidity Sensor, Microset 4 Wall Sensor, and Zio Lite Wall Module.
Wall-Mounted (Room) Sensors
Mounted at standard height on an interior wall, a room temperature sensor measures the temperature occupants actually experience — the most common sensor type for comfort control, feeding directly into thermostat and BMS zone control logic.
Duct Sensors
Installed directly in ductwork, duct sensors measure the temperature of air moving through the system rather than room conditions — used for supply air temperature control, mixed air monitoring in economizer sequences, and confirming coil performance.
Immersion and Strap-On Sensors
For measuring fluid temperature directly — chilled or hot water supply and return — sensors are either inserted into the pipe (immersion) or clamped to the pipe’s exterior (strap-on), depending on whether direct fluid contact or non-invasive installation is preferred.
Outdoor Air Sensors
Mounted on the building exterior, shielded from direct sun and precipitation, outdoor sensors feed economizer control, reset schedules, and heating/cooling changeover logic based on ambient conditions.
Wall Sensor Display Options
Beyond basic sensing, some wall modules — like the Zio Lite — add a local display and setpoint adjustment dial, letting occupants see current conditions and make limited adjustments within a range the BMS allows, rather than acting as a pure sensor with no local interface.
Choosing the Right Sensor Format
| Application | Sensor format |
|---|---|
| Zone/room comfort control | Wall-mounted room sensor |
| Supply/return/mixed air monitoring | Duct sensor |
| Chilled/hot water temperature | Immersion or strap-on sensor |
| Economizer and reset control | Outdoor air sensor |
Combined with Humidity
Many temperature sensors, including several Jaideo carries, combine temperature and humidity sensing in one device — see our Humidity Sensors & Transmitters guide for that combined format.
Frequently Asked Questions
What is the difference between a wall sensor and a duct sensor?
A wall sensor measures room temperature that occupants actually experience for comfort control, while a duct sensor measures the temperature of air moving through ductwork, used for supply air and economizer control.
What is the difference between immersion and strap-on temperature sensors?
An immersion sensor is inserted directly into the pipe for direct fluid contact, while a strap-on sensor clamps to the pipe’s exterior for non-invasive installation without cutting into the pipe.
Why is an outdoor air sensor needed in an HVAC system?
An outdoor air sensor feeds economizer control, reset schedules, and heating and cooling changeover logic based on ambient conditions outside the building.