Engineered Air HVAC Unit HE131/O

Close the upstream manual gas valve

Connect a ¼” (6mm) tube to the outlet pressure tap on the safety shutoff valve

Immerse the opposite end of the ¼” (6mm) tube vertically ½” (13mm) into a clear container of water

Count the number of bubbles appearing during a 10 second period

Is the bubble rate greater than that noted in the manufacturer’s table?

If the bubble rate is greater than that noted in the manufacturer’s table, repair or replace the valve

If bubble rate is less than noted in the table, remove the ¼” (6mm) tube, reconnect the outlet pressure tap plug

Outdoor Air Intakes, Mixing Sections and Dampers

Check cleanliness of outdoor air intakes, screens, and adjacent areas

Verify integrity of outdoor air intakes, screens, and adjacent areas

Ensure proper operation of outdoor air intakes, screens, and adjacent areas

Check set screws on fan wheel for looseness on the shaft

Check set screws on fan bearings for looseness on the shaft

Check set screws on fan pulleys for looseness on the shaft

Check set screws on motor pulleys for looseness on the shaft

Tighten set screws where required

Refer to Table I for Bearing Setscrew Torques by shaft diameter and bearing manufacturer

Is the bearing temperature under 120°F (50°C) in a dusty environment?

Is the bearing temperature under 158°F (70°C) in a clean environment?

Ensure the bearing is rotating slowly during lubrication

Use lithium base lubricant only

Avoid over-greasing the bearings

Select shaft diameter for grease quantity

Refer to fan and/or bearing manufacturers’ literature for additional information

Verify the presence of filters on the air inlet of VFD enclosures

Is the filter replacement based on calendar scheduling?

Enter the scheduled interval for filter replacement (in months)

Is a visual inspection required for filter condition assessment?

Inspect the filter for any visible signs of damage or clogging

Replace the filter if necessary