Honeywell Humidity Sensor H7508A1042

Honeywell Humidity Sensor H7508A1042 – Combined Outdoor Relative Humidity & NTC Temperature Transmitter

The Honeywell Humidity Sensor H7508A1042 is an outdoor-rated, combined relative humidity (RH) transmitter and temperature sensor designed by Honeywell for commercial and industrial HVAC building automation systems (BAS). Engineered to deliver reliable environmental monitoring, the Honeywell Humidity Sensor H7508A1042 incorporates a 3 high-accuracy capacitive relative humidity sensing element paired with a 20 k Omega NTC temperature thermistor inside a single weather-resistant housing.

As shown in the product image, the device features a white, sloped, flame-retardant ABS plastic cover (UL94-HB) engineered specifically to protect internal sensing elements against wind, rain, and environmental debris. By continuously measuring ambient outdoor conditions, it allows building management controllers to optimize fresh air intake, execute enthalpy economizer cycles, and manage indoor air quality efficiently.

Key Features of the Honeywell Humidity Sensor H7508A1042

• Dual Parameter Sensing: Integrates both relative humidity and temperature monitoring into a single outdoor transmitter unit to reduce installation labor.

• Capacitive Humidity Element: Utilizes a capacitance-type humidity sensing element with a pm3% RH accuracy rating (30% to 70% RH range).

• Proportional Voltage Output: Generates a standard 0 to 10 VDC linear output signal corresponding to 0% to 100% RH for easy integration with standard DDC controllers.

• 20 k Omega NTC Thermistor Integration: Includes a passive 20 k Omega NTC temperature sensor (20 k Omega at 25 °C) with high thermal responsiveness.

• Outdoor Weather-Resistant Housing: IP34-rated housing crafted from flame-retardant ABS plastic for long-term outdoor exposure.

• Flexible Power Compatibility: Operates on either 24 VAC or 34 VDC power supplies.

Common Applications and Practical Usage

The ruggedized outdoor design of the Honeywell Humidity Sensor H7508A1042 supports key HVAC and facility management applications:

• HVAC Air Economizer Control: Measures ambient outdoor air enthalpy (temperature and humidity) to determine when outdoor air can be utilized for free cooling.

• Building Automation Systems (BAS): Provides real-time weather data feedback to central direct digital control (DDC) systems to adjust ventilation and heating loads.

• Commercial Ventilation Monitoring: Ensures accurate fresh air dilution in office buildings, schools, shopping centers, and hospitals.

• Industrial Environment Compensation: Monitors external weather shifts to adjust indoor process humidity in textile, paper, and food storage facilities.

Technical Specifications

The electrical, operational, and physical specifications of the Honeywell Humidity Sensor H7508A1042 align with international building control standards:

Installation Guidelines and Best Practices

Mounting Location Tip: Mount the sensor on a north-facing exterior wall shielded from direct solar radiation and driving rain. Avoid mounting above windows, exhaust vents, or heat sources that could skew readings.

• Seal Conduit Passages: Seal wire conduit entry holes thoroughly during installation to prevent warm interior air drafts from altering humidity measurements.

• Maintain Distance from High Voltage: Keep sensor signal wiring at least 15 cm (6 inches) away from 230 VAC power cables to avoid electromagnetic interference.

• Verify Wire Gauge Requirements: Connect wiring using terminal blocks accepting 0.34 to 1.3 mm^2 (AWG 22 to 16) conductors.