Honeywell FEMAEX-DWR3 DGM1A pressure switch

**Product Name:** Honeywell FEMAEX-DWR3 DGM1A Differential Pressure Switch

**Product Overview:**

The Honeywell FEMAEX-DWR3 DGM1A is a robust and reliable differential pressure switch designed for demanding HVAC and industrial applications. It is engineered to monitor air or non-aggressive gas pressure differentials, commonly used for tasks such as filter monitoring, fan status verification, and airflow proving. The device features a high-quality diaphragm sensing element for accurate and responsive switching.

**Key Technical Parameters:**

*   **Switch Type:** Single-pole double-throw (SPDT).

*   **Electrical Rating:** 15 A, 120/240 VAC; 0.5 A, 125 VDC.

*   **Pressure Range:** The adjustable set point range is 0.1 to 3.0 inches of water column (25 to 750 Pa).

*   **Differential (Deadband):** Approximately 0.05 inches of water column (12.5 Pa) at the factory setting. The differential is typically non-adjustable on this model.

*   **Pressure Connections:** Two 1/4" NPT female ports for easy installation into ductwork or pressure tap lines.

*   **Sensing Element:** Diaphragm.

*   **Media Compatibility:** Air and non-aggressive gases.

*   **Operating Temperature Range:** -40°F to 175°F (-40°C to 80°C).

*   **Housing Material:** Durable, corrosion-resistant thermoplastic enclosure rated NEMA 1.

*   **Mounting:** Standard 35mm DIN rail mount or optional surface mounting plate.

*   **Adjustment:** A calibrated, tamper-resistant dial with a slotted shaft for precise set point adjustment. The setting is visible on an integrated scale.

*   **Approvals:** Typically carries UL and CSA listings.

**Functional Description:**

The switch operates by comparing the pressure applied to its two ports. The internal diaphragm deflects in response to the pressure differential, mechanically actuating a snap-action switch. When the sensed differential pressure reaches or exceeds the user-adjusted set point, the switch changes state. The SPDT switch provides a normally open (NO) and a normally closed (NC) contact, offering wiring flexibility for alarm circuits, control interlocks, or equipment start/stop sequences.

**Typical Applications:**

*   Air filter clogging alarms in HVAC systems.

*