Back

Horizon™ Dedicated Outdoor Air Systems OAU-SVX005D-EN: Direct-Fired Unit Maintenance Schedule (Off-Season/Yearly)

This off-seasons/annual procedure inspects all fan wheels and housings. It also helps you inspect all bearings and alignments.
MaintainX
05/03/2021

Horizon™ Dedicated Outdoor Air Systems OAU-SVX005D-EN: Direct-Fired Unit Maintenance Schedule (Off-Season/Yearly)

4 steps
This off-seasons/annual procedure inspects all fan wheels and housings. It also helps you inspect all bearings and alignments.
  • Off-Season/Yearly:

  • Note: It is important to keep screened air intakes clear of obstructions at all times.

  • Lubrication Requirements

  • Some blower motors require lubrication while others do not. Those that require lubrication can be identified by the presence of grease plugs in the motor casing at each end. Motors that do not have grease plugs cannot be greased and are lubricated for the life of the motor bearing.

  • Table 8. Lubrication instructions

  • Lubrication of motors should be done while the motor is warm and at a standstill. Remove and clean all grease plugs and insert a grease fitting in the upper hole in the motor casing at each end (viewed as if motor were sitting horizontally on its base). There may be one or two plugs in each end casing of the motor. Add a small amount of a clean, good grade ball bearing grease (such as Exxon® Polyrex™ EM or equal, with a low pressure grease gun. Run the motor five minutes before removing the grease fittings

  • NOTICE:

  • Bearing Overheating!

  • Excess grease could result in overheating the bearings which could result in equipment damage.

  • Note: On totally enclosed fan cooled (TEFC) motors, the rear end fan housing must be removed to expose the grease plugs.

  • Pillow Block Bearings

  • Pillow block bearings are used on supply blower(s). Bearings have been pre-lubricated with a number 2 lithium based greased. Re-lubrication should be done with a similar grease using a low pressure grease gun. Wipe all grease fittings clean before adding grease. Grease should be added slowly, in small amounts at frequent intervals while the shaft is being manually rotated.

  • A slight showing of grease at the seals with accompanying normal bearing temperature indicates proper lubrication. Normal temperature can range from “cool” to “hot to the touch” depending on size, speed and surrounding conditions.

  • Excessive bearing temperature indicates faulty lubrication. An insufficient amount of grease is suggested by a bearing showing no grease at the seals, and a higher than normal temperature and noise level. Excessive leakage of grease at the seals, and a high operating temperature suggest too much grease.

  • Important: Grease twin blower inner bearing on same schedule as two outer bearings.

  • Frequency of Lubrication

  • Frequency of lubrication depends upon operating conditions. The bearing operating temperature is the best index for determining a re-lubrication schedule. Table 9 gives the frequency of re-lubrication based upon continuous operation for various operating temperatures and can be used as a satisfactory guide for determining when all ball and roller bearings should be lubricated.

  • Table 9. Frequency of lubrication

  • Dampers

  • Dampers should be inspected monthly (daily in icy weather) for securely fastened linkages, and smooth operation. If dampers are binding or excessively noisy, then lubrication may be required. Place one drop of #20 weight machine oil on each blade bearing, and linkage ball joint. Do not over lubricate, and wipe any excess from the area. Ensure to note that dampers over 49 inches long have intermediate bearings which require lubrication.

  • Air Filters

  • ! WARNING

  • Hazardous Voltage!

  • Failure to disconnect power before servicing could result in death or serious injury. Disconnect all electric power, including remote disconnects before servicing. Follow proper lockout/tagout procedures to ensure the power can not be inadvertently energized.

  • All filter banks should be equipped with a manometer or differential pressure switch to indicate when the filters are dirty. Filters should be replaced when the differential pressure across them reaches the manufacturer’s recommended final value.

  • Dirty filter elements should be replaced with a clean element of the same type and size. In addition, it is strongly advised that the air filters be checked every 30 days and replaced with new filters (throw-away type) or cleaned (washable type) as required. Cleanable filters should be given new application of filter coating after washing to maintain optimum performance.

  • Belt Tensions and Adjustments

  • Belt tension is adjusted during the initial run-in and test periods at the factory. However, belts are run as slack as possible to prevent excessive damage to the bearings, yet tight enough to prevent slippage.

  • If necessary, tighten all belts during the first few months of operation, and verify proper tension weekly during the first 60 days, after which, 30-day check intervals are sufficient.

  • NOTICE:

  • MOTOR FAILURE!

  • Tightening any belt or belts by changing the pitch of an adjustable pulley will change the speed of a driven pulley. This could cause the unit to be rendered out of air balance which could result in improper unit operation or motor failure could result.

  • Suggested Belt Tension Method

  • Table 10. Belt tension specifications

  • Gaskets

  • Gaskets are used on doors, inspection covers, some filter racks and some outdoor air dampers. Inspect gaskets periodically and repair or replace as required.

  • ! WARNING

  • Check Gas Tightness of Safety Shut-Off Valves Annually!

  • Gas tightness of the safety shut-off valves must be checked at least on an annual basis. Failure to ensure gas tightness of the safety shut-off valves could result in an explosion which could result in death or serious injury.

  • Annual Maintenance:

  • Heater Maintenance

  • At least a yearly inspection is recommended for heating installations and more frequently for process applications in year-round operation. Experience is the best guide in determining frequency of inspection, but as a minimum, the following procedure should be followed.

  • ! WARNING

  • Hazardous Voltage!

  • Failure to disconnect power before servicing could result in death or serious injury. Disconnect all electric power, including remote disconnects before servicing. Follow proper lockout/tagout procedures to ensure the power can not be inadvertently energized.

  • ! WARNING

  • Combustible Materials!

  • Failure to maintain proper clearance between the unit heat exchanger, vent surfaces and combustible materials could cause a fire which could result in death or serious injury or property damage. Refer to unit nameplate and installation instructions for proper clearances.

  • Heater Maintenance:

  • Inspection and Maintenance of Gas Ports

  • Conduct initial inspection within the first month after commissioning. Visually check the gas ports of the new burner assemblies for any piping scale or debris. Use pin vise with drill bit to remove.

  • Annual inspections are normally adequate once the initial debris is removed. The operating conditions of the burner will determine how frequently maintenance is actually required.

  • Use of an electric drill motor is not recommended unless both pin vise and drill (see Figure 18) can be chucked-up in a variable-speed drill unit.

  • Care should be given in this instance due to the nature of drill bits and their ability to easily snap off in a port when using a drill motor. Removal of broken bits from the gas port is difficult.

  • Alternate drill sizes to be used are 5/64 in. (for #47) and 1/16 in. (for #50).

  • Figure 18. Gas port inspection

  • Final Process

Please note that any procedure, checklist, or other document available in the MaintainX Global Procedure Library is provided for general education and information only and does not constitute legal, medical, or financial advice. MaintainX makes the materials available AS IS and AS PROVIDED, without warranties of any kind. By downloading or using any such materials, you assume the risk that they may not be appropriate for your specific situation and agree that you are solely responsible for any such use, including compliance with applicable law and with meeting any conditions of product warranties.