Sensible or total energy wheels normally operate with a minimum amount of required maintenance. The following maintenance items must be inspected for optimum wheel performance:

• cleanliness of the wheel media surface
• inspection of the face seals (contact and/or labyrinth)
• inspection of the perimeter seal (contact and/or labyrinth)
• regular servicing of the drive motor and/or speed reducers
• inspection of the drive belt(s)/pulleys
• inspection of the wheel bearings (polymer and/or ball bearing).

Cleaning of the wheel media surface is normally not necessary due to the self-cleaning effect of the opposing airflows and properly scheduled filter maintenance. In the event that the wheel media surface does require cleaning, it should be noted that cleaning methods suitable for one type of media are not necessarily suitable for other types. Non-hygroscopic wheels can be cleaned using low-pressure steam, compressed air, hot water with mild cleaning solutions or a non-polarized solvent. Hygroscopic wheels can be cleaned by vacuuming the face of the wheel or by using dry, compressed air. Hygroscopic wheels must not be washed or be subject to high humidity as the desiccant material (silica gel) will dissolve and be lost from the media.

Inspection of the air seals can consist of the: face/contact seal, perimeter seal(s) and labyrinth seal. These seals should be periodically inspected for proper clearance, operation and signs of unusual wear. Adjustment on labyrinth seals is required to maintain a clearance of the legs of the seal to the wheel surface of 1/16".

Wheels with belt drive(s) should be inspected for proper tension. Flat belts are usually in the range of 0.5% to 1.0% of belt tension. Timing belts are 0.1% and less. V-link belts are properly tensioned by removing 4 to 6 link sections from the measured length. Should the link V-belt need a tension adjustment, simply remove one of the link sections and re-install the belt.

During belt inspection, look for signs of unusual wear or fraying on the belt surface. Pulleys should be inspected for proper alignment and perpendicularity to the belt. Check the pulley set screw(s) for proper tightness. The following are some examples of wheel drive systems:

• Flat belt direct drive
• Flat belt gear drive
• V-link belt, gear drive

Permanently lubricated and sealed ball bearings are usually used on rotary wheels. Servicing of the bearing is normally required. Refer to the Pillow Block Bearings information later in this Maintenance Section. Non-metal bearings and non-ball bearings, such as Ultra High Molecular Weight Polyethylene (UHMW) or other polymeric bearings do not require any lubrication during the life of the bearing. Periodic inspections for wear are recommended as part of a good maintenance program.

The heat pipe heat exchanger operates with the least maintenance of all the air-to-air energy recovery technologies. Heat pipes require periodic maintenance to ensure the maximum efficiency of the charged aluminum finned pipe. The frequency of maintenance required will depend on the application and amount of particulates and condensibles in the airstreams. Accumulated dirt or dust reduces the air circulation, pipe optimum performance and increases pressure drop. Proper filter maintenance will ensure a clean environment for the heat pipe and maintain optimum performance. It is recommended that the heat pipe be cleaned at least once a year or every 6 months in dirty environments or those with heavy exhaust air particulates. Cleaning can consist of:

• the use of hot water (less than 120°F) and mild detergents under pressure
• compressed air
• other cleaning solutions - must be investigated as to their reaction to aluminum.

All heat pipe configurations have full length condensate pans, which will allow the usage of high pressure water with cleaning solutions inside of the unit. The by-pass damper must be checked periodically to ensure correct and proper function. When used, frost control operation must must be checked semi-annually.

Do not attempt any maintenance of a fan unless the electrical supply has been locked out and the impeller has been secured. Fan assemblies having badly worn blades or loose blades should be replaced or rebuilt. Rebuilt or repaired (including hard metal surfacing) fan assemblies require careful balancing before being returned to service. Experienced personnel should give the wheel a running balance check by operating it on its own shaft and bearings.. Standard fans handling outdoor air and building return air conditions should have the internal parts cleaned once per year with compressed air to reduce any dirt, dust, lint or larger particulates that have bonded to the fan housing or impeller(s). This cleaning process will keep the fans from becoming unbalanced. Standard fans handling corrosive fumes should have the internal parts air brushed or scraped clean and then painted with a corrosion-resisting paint. This process should be repeated when the paint film begins to show signs of deterioration.

Lubrication of bearings is required. The bearings are pre-lubricated from the factory, however if the bearings are being operated in a damp, dusty or corrosive environment, the bearings should be filled completely with grease to keep the contaminates out of the bearing cavity. Before start up, be sure the bearings are cleaned and re-lubricated. Verify that all tie down bolts are tight. Verify that the motor is secured down and adjusted. Verify that all safety guards and items are in place and functional. Verify that the fan wheel is free to turn and is rotating in the proper direction. Check the inlet space clearance between the blower and blower impeller.

Check the set screw in the hub for tightness to the shaft. Check the wheel for any signs of movement or loose blades. Check the keyway for tightness. Verify that the motor shaft and the fan shafts are parallel. Verify that the pulleys are aligned. Verify proper belt tension on the fan assembly. If a coupler is used with direct drive fans, verify that the coupler assembly is lubricated. Verify that the coupling, fan shaft and motor shaft are aligned properly (refer to coupler limits).

Vibration can be caused by the following and should be checked immediately:

• bearing drive alignment
• fan out of balance
• shaft straightness
• sheaves out of balance
• loose or worn bearings
• worn or corroded wheel
• loose mounting bolts
• motor out of balance
• accumulation of particulates on wheel (dirt, dust, lint)

Successful operation of a fan depends on the reliability operation of the bearings and balance of the wheel. A regular, scheduled maintenance program is imperative.

A regularly scheduled coil cleaning will help maintain operating efficiency. Regular cleaning of the evaporator condenser coils of an air conditioning system will increase equipment life.

The coils are the means that provide the actual transfer of heat. Anything that insulates against heat transfer robs the system of its efficiency, which increases operating costs.

Anything that contacts the coil surface can have an insulating effect. Some examples include: dirt, grease, dust, corrosion, insects, cigarette smoke, bacteria and micro-organisms. These items can act as insulating barriers and must be removed from the system so it can operate efficiently.

Coil cleaners come in two forms: powder and liquid. Most coil cleaners fall into four categories:

• Acid - very effective at removing any material from coils, but produce strong, choking vapors.
• Alkaline - very effective cleaning results for all conditions, but produce a mild odor and are caustic.
• Solvent - good for removing grease and smoke residue, but not heavy particulates or corrosion. Solvents are flammable and give off strong smells and vapors.
• Detergent - strong, foaming, slightly alkaline detergent. Good at removing grease and smoke residue, but not particulates or corrosion. Usually require a thorough rinsing.

Typical cleaners are allowed to remain on the coils for five to twenty minutes.

A clean coil is not necessarily a bright coil. Usually the brighter the coil surface is after a cleaning; the more metal you have removed. Care should be taken in choosing the right cleaner so the life of the coil is not diminished.

In general, evaporator or cooling coils are typically damp or wet from condensate and are placed in cool, dark areas. This environment lends itself to breeding bacteria and other micro-organisms, some dangerous or even deadly.

DO NOT attempt maintenance of a motor unless the electrical supply has been locked out. Always follow the manufacturer's recommended maintenance schedule.

Inspect the motor at regular intervals, approximately every 500 operating hours or every 3 months. Keep the motor clean and the ventilation openings clear.

The interior and exterior of the motor should be kept free of dirt, oil, grease, water, etc. Watch for accumulated build up that can block ventilation openings. If a motor is not properly ventilated, overheating can occur, causing premature motor failure. The motor insulation intensity can be checked using a "megger".

Anti-friction bearing grease used in grease-lubricated anti-friction bearings will lose its lubricating ability over time. For a given bearing construction and assembly, the lubricating ability of the grease over time depends primarily on: the type of grease, the size of the bearing, the speed of operation of the bearing and the severity of operating conditions.

A high-grade ball and roller bearing grease of medium consistency and polyurea base is recommended for re-lubrication. Recommended greases for standard service conditions are: Shell Dolium R, Chevron SR1, Darmex 707 (2 pole motors). See manufacturer's lubrication recommendations.

The re-lubrication procedure consists of the following steps:

• Clean the grease fitting.
• Remove the grease outlet plug.
• Add the recommended amount of grease. Be sure the grease to be added is compatible with the grease already in the motor. If the motor is to be greased while running, a larger quantity of grease will have to be added. Stop adding when new grease appears at the shaft hole in the end plate or purge outlet plug.
• Replace the plug.

Inspect all gear drives regularly for wear and alignment. Initial inspection should take place after 24 hours; second inspection after 100 hours; third inspection after 500 hours and once per year thereafter. Check the tooth contact pattern. Tooth should show full face contact.

Initial inspection of the set screw and bushing cap screws should occur after 24 hours; second inspection after 100 hours; third inspection after 500 hours and once per year thereafter. Check all set screws and/or tapered bushing cap screws for looseness. Re-tighten to recommended torques if necessary.

Lubrication should occur as recommended by the manufacturer's maintenance interval. Use a good grade mineral oil. S.A.E. number and frequency of changing lubricant depends on the application.

Initial lubrication change should occur after the first 500 hours or 5 weeks. Subsequent changes every 2,500 hours or 6 months, whichever comes first. Under severe conditions change the oil every 1 to 3 months. Drain the used oil from the box. Flush the box if oil has become contaminated. Refill the box to the proper level with new lubricant.

The initial lubrication level inspection should occur after the first 24 hours; second inspection after 100 hours; third inspection after 500 hours. Level lubricant inspections should be conducted periodically thereafter. Check the oil level. Add oil if necessary. If oil is required, check for leakage by removing the end cover and seal cage cap screws. Inspect the seal lips and seal cage. Seal replacement is recommended when the box is disassembled, but if replacement is not done, protect the seal life by wrapping the shaft with thin, strong paper coated with oil or grease before removing or replacing the seal cage assembly.

Initial inspection of the mounting bolts should occur 24 hours; second inspection after 100 hours; third inspection after 500 hours and once per year thereafter. Check the mounting bolts for tightness. Make sure the gear box has not slipped. Re-tighten bolts, if necessary.

Initial inspection of the set screws should occur after 24 hours; second inspection after 100 hours; third inspection after 500 hours and every 6 months thereafter. Check the set screw tightness. Re-tighten, if necessary.

Initial inspection of the locking collars should occur after 24 hours; second inspection after 100 hours; third inspection after 500 hours and every 6 months thereafter. Check the eccentric collar tightness on the shaft. If loose, turn in the direction of shaft rotation until hand tight. Then tighten the collar set screw to the torque values recommended.

In order to determine the appropriate lubrication intervals, the following operating conditions and temperatures need to be considered.

Add grease slowly with the drive in operation. When lubricant begins to come out of the seals, the bearing will contain the correct amount of lubricant.

Initial inspection of the mounting bolts should occur after 24 hours and second inspection after 500 hours. Every 12 months thereafter. Check the mounting bolts for tightness. Re-tighten, if necessary.

Initial inspection of bearing alignment should occur after 24 hours; second inspection after 100 hours; third inspection after 500 hours and once per year thereafter. Bearing alignment is critical on many ball and roller bearings designated as "self-aligning". Alignment should center the shaft within one-half of the normal radial clearance at the edge of the housing, to prevent excessive dust seal wear and possible shaft scoring.

Initial inspection to check for damaged seals should occur after 100 hours and the second inspection after 500 hours. Every 12 months thereafter. Check seals to make sure they have not been punctured or damaged by foreign objects.

Initial inspection of bearing temperature should occur after 24 hours; second inspection after 100 hours; third inspection after 500 hours and every 12 months thereafter. Check to see if the bearing is running hot. Bearing temperature should NOT exceed 200°F.

Initial inspection for bearing noise should occur after 24 hours; second inspection after 100 hours; third inspection after 500 hours and every 12 months thereafter. Check for bearing noise. Bearing should have a soft, smooth purring sound.

When V-belts must be replaced, replace the entire set of belts with new belts for multi groove sheaves. New belts will not work properly in conjunction with used belts, due to the differences in belt lengths.

Initial inspection for sheave groove wear should occur after 8 hours. Second inspection after 8 hours; second inspection after 24 hours; third inspection after 100 hours and every 6 months thereafter. Check for belt ride in the groove. In multiple groove drives, belt ride should be uniform, not more than 1/16" above or below top of the sheave groove. Check groove area for wear. Side wall of groove should be straight, not dished out. Bottom of groove should show no signs of belt contact.

Initial inspection for sheave run out should occur after 24 hours; second inspection after 100 hours; third inspection after 500 hours and every 12 months thereafter. Check the sheave by eye for run out. If run out is excessive, it can easily be seen by a visual inspection. If run out is noticeable, check sheave for the source of the problem and correct it.

Initial inspection for heat build up and proper ventilation should occur after 24 hours; second inspection after 100 hours; third inspection after 500 hours and every 12 months thereafter. Check the belts for heat. Ambient temperature should not exceed 140°F. Contact temperature should not exceed 180°F. Make sure drives are properly ventilated.

Initial inspection for clean belts and sheave grooves should occur after 24 hours; second inspection after 100 hours; third inspection after 500 hours and every 6 months thereafter. Inspect the belts for contaminates, such as oil or grease. Wipe belts clean with detergent and water. Inspect sheave grooves for build up of such material and remove, if necessary.

Initial inspection for belt tension should occur after 8 hours; second inspection after 24 hours; third inspection after 100 hours and every 6 months thereafter. Check the belt tension using a belt tension checker or similar spring scale. Excessive belt tension is the number one cause of blower bearing failure. Proper belt tension and pulley alignment are essential for trouble free operation. A simple "rule of thumb" for checking belt tension is to grasp the belt with one hand in the middle of the pulleys to obtain a total deflection of approximately 1" (25mm) [1/2" (13mm) each side] should be easily attained. Insufficient deflection indicates that the belt is too tight, resulting in noise from excessive vibration, premature bearing failure and short belt life. Tight belts may overload a motor that would otherwise be adequate. Fan RPM can be adjusted to achieve the desired airflow by setting the adjustable sheave on the motor shaft. Pulley set screw torque setting 110 in lbs to 130 in lbs.

Initial inspection of the sheave alignment should occur after 8 hours; second inspection after 24 hours; third inspection after 100 hours and every 12 months thereafter. Check the alignment with a straight edge, string or machinist level. Correct the alignment to be as near perfect as possible.

Initial inspection for mismatched belts should occur after 8 hours; second inspection after 24 hours; third inspection after 100 hours and every 6 months thereafter. Check the belt sag on the slack side of the drive. All belts should have a slight bow. If this bow is not uniform with all belts, replace the entire set with a matched set.

Initial inspection for worn belts should occur after 8 hours; second inspection after 24 hours; third inspection after 100 hours and every 6 months thereafter. Check wear surfaces of the belt for excessive wear. If belts have a slick, glazed look, they are slipping. Never replace only one belt in a used set, as used belts will elongate. Replace the entire set if replacement is necessary.

Initial inspection of the sheave set screws and/or bushing cap screws should occur 8 hours; second inspection after 24 hours; third inspection after 100 hours and every 12 months thereafter. Check all set screws and/or bushing cap screws for looseness. Re-tighten to a recommended torque of 110 in lbs to 130 in lbs, if necessary.

Due to the shifting and jarring that is associated with shipping, an initial inspection after 8 hours is recommended for certain types of maintenance.

Initial inspection of belt tension should occur after 8 hours; second inspection after 24 hours; third inspection after 100 hours and every 6 months thereafter. Check the belt tension using a belt tension checker or similar spring scale. When the drive is in operation, both sides of the belt should be straight from pulley to pulley.

Initial inspection of the sheave alignment should occur after 8 hours; second inspection after 24 hours; third inspection after 100 hours and every 12 months thereafter Check the alignment with a straight edge, string or machinist level. Correct the alignment to be as near perfect as possible. Check that the motor shaft and fan shaft are parallel.

Initial inspection for worn belts should occur after 8 hours; second inspection after 8 hours; second inspection after 24 hours; third inspection after 100 hours and every 12 months thereafter. Check the wear surfaces of the belt for excessive wear. If belts have a slick, glazed look, they are slipping. Check the belt capacity, belt tension and sheave alignment.

Initial inspection of the sheave set screws and/or bushing cap screws should occur after 8 hours. Second inspection after 24 hours. Third inspection after 100 hours. Every 12 months thereafter. Check all set screws and/or bushing cap screws for looseness. Re-tighten to recommended torque: 110 in lbs to 130 in lbs, if necessary.

Initial inspection of the sheave mount should occur after 24 hours. Second inspection after 100 hours. Third inspection after 500 hours. Every 12 months thereafter. Check visually for sheave mount. If run out is noticeable, check for source of problem and correct.

Initial inspection to check for sheave groove wear should occur after 8 hours; second inspection after 24 hours; third inspection after 100 hours and every 12 months thereafter. Check the groove area for excessive wear. Side wall of groove should be straight, not dished out.

Initial inspection for heat build up and proper ventilation should occur after 24 hours; second inspection after 100 hours; third inspection after 500 hours and every 12 months thereafter. Check the belts for heat. Ambient temperature should not exceed 140°F. Peak contact temperature should not exceed 180°F. Be sure all drives are properly ventilated.

Initial inspection of the belts and sheave should occur after 24 hours; second inspection after 100 hours; third inspection after 500 hours and every 6 months thereafter. Inspect the belts for contaminates such as oil or grease. Wipe belts clean with detergent and water. Inspect sheave grooves for build up of such material and remove, if necessary.

Typically the gas modules used for indirect and direct gas fire require minimal maintenance. The following steps should be taken every 12 months (unless otherwise stated):

• Check the condition of the flame every 6 months.
• Remove the burner drawer assembly. Clean out debris or particles. Adjust the combustion to a minimum of 75% of minimum efficiency.
• Before the heating season, inspect the heat exchanger (indirect gas) for leaks. Cracks in the heat exchanger must be welded or the heat exchanger must be replaced.
• Check for rust in the flue stack and heat exchanger section in general. Replace parts as necessary.
• Check for gas leaks in the gas train and burner piping, by applying a soapy water solution on all fittings. Tighten as necessary.
• If the heat exchanger requires replacement, refer to the Installation, Operation and Maintenance Manual for the unit.
• Check the burner module motor linkage.
• Inspect and check the operation of the flame safety relay.