Series-RHP

Supported Applications

The Series RHP Humidity and Temperature Transmitter combines a voltage or current humidity output with a passive thermistor or RTD temperature output in a single device. Its polymer capacitance humidity sensor reduces the long-term effects of condensation, fog, and high humidity, giving the transmitter the stability needed for continuous monitoring and control.

Using duct and outside-air (OSA) mounting configurations, the Series RHP monitors and controls humidity, or both humidity and temperature, in building energy-management systems, commercial and residential HVAC, clean rooms, museums, and climate chambers. Optional accessories such as a radiation shield and sintered filter adapt the outside-air version to demanding outdoor exposures. Disconnect the power supply before installation, use electrostatic-discharge precautions during wiring, and avoid locations subject to severe shock or vibration, excessive moisture, or corrosive fumes.

Operating Conditions & Performance

The transmitter measures relative humidity over 0 to 100% RH and temperature over -40 to 140°F (-40 to 60°C). Relative humidity accuracy depends on the accuracy grade: the RHP-2XXX models are ±2% over 10-90% RH @ 25°C, the RHP-3XXX models are ±3% over 20-80% RH @ 25°C, and the RHP-5XXX models are ±5% over 20-80% RH @ 25°C. Hysteresis is ±1%, repeatability is ±0.1% typical, and resolution is 0.1% RH and 0.1°F (0.1°C). Response time is 15 s.

Temperature accuracy is set by the sensor fitted: a thermistor at ±0.2°C @ 25°C (±0.36°F @ 77°F), a DIN Class B RTD at ±0.3°C @ 0°C (±0.54°F @ 32°F), or a solid-state band-gap sensor at ±0.9°F @ 77°F (±0.5°C @ 25°C). The compensated temperature range is -4 to 140°F (-20 to 60°C), and storage is rated over -40 to 176°F (-40 to 80°C).

Output is model dependent: a 4-20 mA current signal or a 0-5/10 V voltage signal at 5 mA max. Power requirements follow the output — the 4-20 mA loop-powered models use 10-35 VDC, while the 0-5/10 V output models use 15-35 VDC or 15-29 VAC; the 4-20 mA models are not designed for AC voltage operation. Wiring lands on a removable screw terminal block.

Enclosure protection is NEMA 4X (IP66) for the OSA models and for the duct-mount housing. Housing materials include a PVC UL 94 V-0 duct sensor tube, a polycarbonate/ABS blend sensor cap, and a Makrolon polycarbonate UL 94V-HB electronics housing and cover; the OSA version is polycarbonate. The transmitter is CE marked.

Configuration Options

Every model is built to the pattern RHP - Accuracy - Housing Type - Temperature Sensor - RH Output - Options, so a code communicates several independent capability choices:

• Accuracy grade: the leading digit sets relative-humidity accuracy — 2 for ±2% (10-90% RH), 3 for ±3% (20-80% RH), and 5 for ±5% (20-80% RH), all specified @ 25°C.
• Housing and filter: the series is offered in duct-mount and outside-air (OSA) configurations; the OSA sintered-filter versions (RHP-XSXX) accept the RHRS radiation shield and have replacement sensors available.
• Temperature sensor and RH output: remaining code positions select the temperature sensor (thermistor or RTD) and whether the humidity output is current or voltage, which in turn sets the supply-voltage requirement.

An optional local display is available for the duct-mount models.

Key Product Differences

This grouping of the Series RHP includes the following outside-air models:

• RHP-2O22 — ±2% accuracy grade.
• RHP-3O22 — ±3% accuracy grade.
• RHP-3S22 — ±3% accuracy grade, sintered-filter version.

Replacement filters and a retrofit tool are available as accessories, including the A-RHP-FC replacement hydrophobic filter and the A-RHP-RT retrofit tool.