Precedent™ Rooftop Units: Monthly Maintenance

Cooling Season

• Check the unit’s drain pans and condensate piping to ensure that there are no blockages.

• Inspect the evaporator and condenser coils for dirt, bent fins, etc. If the coils appear dirty, clean them according to the instructions described in “Coil Cleaning” later in this section.

• Manually rotate the condenser fans to ensure free movement and check motor bearings for wear. Verify that all of the fan mounting hardware is tight.

• Inspect the F/A-R/A damper hinges and pins to ensure that all moving parts are securely mounted. Keep the blades clean as necessary.

• Verify that all damper linkages move freely; lubricate with white grease, if necessary.

• Check supply fan motor bearings; repair or replace the motor as necessary.

• Check the fan shaft bearings for wear. Replace the bearings as necessary.

• Check the supply fan belt(s). If the belts are frayed or worn, replace them. Refer to the “Fan Belt Adjustment-Belt Drive Units,” p. 36 for belt replacement and adjustments.

• Verify that all wire terminal connections are tight.

• Remove any corrosion present on the exterior surfaces of the unit and repaint these areas.

• Generally inspect the unit for unusual conditions (e. g., loose access panels, leaking piping connections, etc.)

• Make sure that all retaining screws are reinstalled in the unit access panels once these checks are complete.

With the unit running, check and record the following:

• ambient temperature

• compressor oil level (each circuit)

• compressor suction and discharge pressures (each circuit)

• superheat and subcooling (each circuit)

Heating Season

• Inspect the unit’s air filters. If necessary, clean or replace them.

• Check supply fan motor bearings; repair or replace the motor as necessary.

• Inspect both the main unit control panel and heat section control box for loose electrical components and terminal connections, as well as damaged wire insulation. Make any necessary repairs.

• Verify that the electric heat system operates properly.

Regular coil maintenance, including annual cleaning enhances the unit’s operating efficiency by minimizing the following:

• Compressor head pressure and amperage draw

• Evaporator water carryover

• Fan brake horsepower

• Static pressure losses

• Airflow reduction

Hail Guard Removal

• Unlatch hail guard.

• Pull the top of the hail guard outward until the fastener studs are free of the retaining nuts.

• Lift the hail guard from the lower retaining bracket and set aside.

Safe Handling Practices:

• Remove enough panels from the unit to gain access to the coil.

• Protect all electrical devices such as motors and controllers from any over spray.

• Straighten any bent coil fins with a fin comb.

• Mix the detergent with water according to the manufacturer’s instructions. If desired, heat the solution BUT DO NOT EXCEED 150ºF maximum to improve its cleansing capability.

• Pour the cleaning solution into the sprayer. If a highpressure sprayer is used: a. do not allow sprayer pressure to exceed 600 psi. b. the minimum nozzle spray angle is 15 degrees. c. maintain a minimum clearance of 6" between the sprayer nozzle and the coil. d. spray the solution perpendicular (at 90 degrees) to the coil face.

• Spray the leaving-airflow side of the coil first; then spray the opposite side of the coil. Allow the cleaning solution to stand on the coil for five minutes.

• Rinse both sides of the coil with cool, clean water.

• Inspect both sides of the coil; if it still appears to be dirty, repeat Step 6 and Step 7.

• Reinstall all of the components and panels removed in Step 1 and any protective covers installed in Step 2.

• Note: For units equipped with hail guards follow reinstallation procedure listed below.

• To reinstall the hail guard, locate the bottom of the hail guard in the lower bracket and secure it to the upper unit bracket with the attached fasteners.

• Restore the unit to its operational status and check system operation.