Series BYDS Bypass Damper Switch

Controls Zone Static by Modulating Motorized Damper

The Series BYDS Bypass Damper Switch is designed to control motorized bypass dampers. As individual zone dampers open and close, the system static pressure will rise and fall. In order to maintain proper airflow and static pressure through the HVAC system, a bypass system incorporating a floating type motorized damper and a static pressure control should be incorporated. A typical on/off pressure switch cannot operate in this application due to the high cycle rate that would result, eventually causing contact burnout. The BYDS static pressure control is equipped with a solid-state switching and timing circuit to enhance operation and improve long-term reliability in this demanding application.

The BYDS Bypass Damper Switch is designed for use with a three wire floating point damper actuator used to control the static pressure on zone control systems requiring motorized bypass dampers. A bypass damper, bypasses air from the discharge air side of the HVAC unit back in the return air side. The air flow is modulated in order to maintain a constant static pressure in the system as individual zone dampers open and close. The static pressure control is equipped with solid-state switching which dramatically increases the life of the control. On an increase in static pressure the BYDS will send 24 volts out and start the actuator to drive open. When the static pressure reaches set-point the actuator will stop. After a ten second delay the actuator will start to drive the damper closed if there has not been an increase in static pressure. A green LED indicates when the damper is in the open position or being driven open. A 24 VAC transformer is required to power the BYDS control and damper actuator. The unit includes tubing and two static pressure probes.

Additional ranges can be found on the Series ADPS/EDPS web page.

Product Applications

  • Air filter and ventilator monitoring
  • Industrial cooling circuits
  • Fire-protection damper control
  • Ventilation duct monitoring
  • Fan heater overheating protection
  • Heat exchanger frost protection

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

COVID-19 Update: Due to high customer demand, lead time on some products may be up to two weeks. While this is a developing health situation, we are working continuously to take the necessary measures to ensure that the products you need are available with minimal interruption.

Model Description Usually Ships* Price Code Order
Ships: Consult Factory
Price: $62.50
Bypass damper switch, 2.00-10.00" w.c., M20 connection, incl installer kit Consult Factory* $62.50 B Order


Air and non-combustible, compatible gases.
Diaphragm Material: silicone; Housing Material: switch body: PA 6.6 and POM; Cover: polystyrene.
Temperature Limits:
Process and ambient temperature from 32 to 122 °F (0 to 50 °C).
-40 to 185°F (-40 to 85°C).
Pressure Limits:
Max. Operating Pressure: 40" w.c. (10 kPa) for all pressure ranges.
Switch Type:
Single-pole double-throw (SPDT).
Electrical Rating:
1A @ 24 VAC.
Electrical Connections:
Screw terminal block. M20 x 1.5 with cable strain relief or 1/2" NPT connection.
Process Connections:
5/16" (7.94 mm) outside diameter tubing, 1/4" (6.0 mm) inside diameter tubing.
Enclosure Rating:
NEMA 13 (IP54).
Mounting Orientation:
Vertically, with pressure connections pointing downwards.
Mechanical Working Life:
Over 106 switching operations.
4.4 oz (125 g).
Agency Approvals:
5 year limited warranty.


  • Units include 2 plastic static pressure tips and 7 ft. (2.1 m) of PVC tubing.
  • Adjustment knob changes switching pressure easily with a pressure gage reducing components for application.
  • Low cost device makes it an excellent solution in BAS and HVAC applications requiring duct control and monitoring.
  • Relay contact allows simple integration with DDC or building systems.


Model Number Description Usually Ships* Price Code Order
“L” type metal mounting bracket with screws. A-288 “L” type metal mounting bracket with screws. Next Day $3.60 Order
“S” type metal mounting bracket with screws. A-289 “S” type metal mounting bracket with screws. Next Day $3.60 Order
Plastic static pressure tip. A-480 Plastic static pressure tip. Next Day $0.90 Order
Installer kit, (includes 2 static pressure tips and PVC tubing). A-481 Installer kit, (includes 2 static pressure tips and PVC tubing). Next Day $4.40 Order
4 A-489 4" 303 SS straight static pressure tip with flange, 1/4" hose barb. Next Day $6.90 Order

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