Orifice sizing is determined by the altitude and the BTU rating of the individual burner

ensuring efficient heat dissipation during high-ambient operations

it maintains precise drive ratios and reduces vibration across the motor shaft and blower assembly

check the ohm resistance of the coil

providing ample coverage to conceal footprint marks

Johnson Controls T-4000-2138 Plastic Cover Orifice sizing is determined byThe Johnson Controls T 4000 2138 is a professional grade beige plastic thermostat cover designed specifically for T 4000 series pneumatic room thermostats. This field standard component provides a clean, streamlined aesthetic for commercial HVAC systems where tamper resistance and a minimalist profile are required. Engineered for versatility, the T 4000 2138 supports both horizontal and vertical mounting configurations, accommodating various pneumatic