Series 657 Relative Humidity/Temperature Transmitter

Dual Channel Design for Simultaneous 4-20 mA Output Signals

The Series 657 Relative Humidity/Temperature Transmitters provide two 4-20 mA channels to produce separate output signals for both relative humidity and temperature. These devices deliver ±2% accuracy for humidity and ±1°F for temperature measurements. Stainless steel probe can be easily mounted to most ductwork using either of the two optional kits below.

*NOTE: The configurator is only available for the Series 657C.

Product Applications

  • Cleanroom monitoring
  • HVAC/building control monitoring

Models & Ordering

Shipping Information

All shipping times are dependent on product availability at time of shipment.

Although we make every effort to ensure a continuous supply of our products, occasional circumstances may force us to temporarily run out of a product, or have shipping delays. Should this occur, customers will be notified soon after placement of any orders for such products and, if applicable, items will be put on backorder. For orders requiring expedited shipment, our customer service team can be contacted to confirm product availability

Build Your Custom Part. Use our Product Configurator

Model Description Usually Ships* Price Order
Ships: Next Day
Price: $346.00
Relative humidity/temperature transmitter. Next Day* $346.00 Order
Ships: Next Day
Price: $383.00
Relative humidity/temperature transmitter. Next Day* $383.00 Order

Can't find what you need? Build Your Custom Part. Use our Product Configurator


Dry clean air.
Relative Humidity: 0-100%; Temperature: 32 to 212°F (0 to 100°C).
Relative Humidity: ±2% (10-90% RH), ±3% (0-10% and 90-100% RH); Temperature: ±1°F (0.5°C).
Temperature Limit:
32 to 140°F (0 to 60°C).
Pressure Limits:
1 psi (.07 bar).
Compensated Temperature Range:
32 to 140°F (0 to 60°C).
Power Requirements:
10-35 VDC.
Output Signal:
2 channels each 4-20 mA. Loop powered on RH channel.
Electrical Connections:
4 screw type terminal.
Mounting Orientation:
Mount in any position.
657-1: Stainless steel 5/16" x 10"(0.8 x 25.4 cm); 657C-1: 5/16" x 9-1/10" (0.8 x 23.1 cm).
657-1: 5.5 oz (156 g); 657C-1: 10 oz (284 g).


  • Polymer film humidity and thin film RTD temperature sensors offer highly reliable and stable measurements
  • Remote mount housing offers installation flexibility (657-1)
  • Rugged die-cast aluminum housing is great for industrial applications (657C-1)


Model Number Description Usually Ships* Price Order
Split flange. A-158 Split flange. Next Day $17.50 Order
Mounting gland with 1/2 A-159 Mounting gland with 1/2" male NPT. Next Day $34.50 Order


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