Tjernlund Duct Airstat senses positive pressure in a forced air heating and/or cooling system. The single pole, single throw, snap-acting switch is activated by a diaphragm with a factory installed sampling tube inserted directly into the duct or plenum. The Duct Airstat can be used to initiate such auxiliary devices as: Duct Boosters, Electronic Air Cleaners, Electrical Duct Heaters, and Humidifiers. The electrical contacts of the switch are closed upon sensing positive air pressure generated by the blower. FEATURES:High SensitivityMaximum Temperature Limit of 190 F.Simple InstallationSelf-Sealing Factory Mounted Sampling TubeMounting Hardware Included Switch activates Duct Booster by sensing positive pressure on either plenum, trunk, or branch linesSPECIFICATIONS:ELECTRICAL RATING:278 VA Pilot Duty at 24 Volts AC300 VA Pilot Duty at 115 to 277 Volts AC15 AMPS Non-Inductive to 277 Volts ACELECTRICAL SWITCH:SPST, N/O, Snap Action Contacts, Non AdjustableOPERATING PRESSURE / POSITION:On pressure rise at +.05 + .02" W.C. (Diaphragm Vertical)MAXIMUM PRESSURE:1/2 PSIOPERATING TEMPERATURE RANGE:-40 to 1900 F.SAMPLING TUBE:Self-sealing, factory mounted tubeDIMENSIONS:5 3/4" H X 3 1/4" W X 3"DLOCATION AND MOUNTING:1. The duct Airstat must be mounted in a vertical position.2. Drill a 11/32" hole in the duct or plenum to permit the insertion the pressure probe. If furnace has central air-conditioning, care must be taken so as not to drill into the cooling coil when mounting the Duct Airstat on the furnace plenum.3. Insert the pressure probe into the drilled hole, position the Duct Airstat and mark the mounting holes. If necessary, bend the mounting feet with pliers to match the contour of the duct or plenum.4. Remove control and drill or punch two 1/8" holes for mounting screws.5. Using the two sheet metal screws furnished, fasten the Duct Airstat to the duct or plenum. Sealing gasket must be mounted on pressure probe to ensure minim