Maintenance, Inspect Regularly, Motors, Casings, Coils

V. MAINTENANCE

A.INSPECT REGULARLY

Under average conditions, it is recommended that unit heaters be inspected before every heating season

— more often in locations where air is contaminated with corrosive fumes, dust, soot or oil spray. Check for dirty, clogged coils, excessive vibration and loose connections. Inspect piping, strainers, traps, ﬁttings, etc.

B.MOTORS

1.Cleaning

Remove grease and dirt on motor during each inspection or lubrication. Open frame motors should be blown clean every heating season, or whenever coils are cleaned, whichever is sooner.

2.Lubrication

Lubricate motor according to manufacturer’s instructions located on the motor. When no motor oiling instructions are on the motor, oil the motor every two thousand hours of operation with SAE20 motor oil for units in normal applications. Adjust oiling according to usage and atmosphere. Some motors do not have oil ﬁttings. These motors are lubricated for long life and do not require further lubrication.

3.Overload Protection

A change in line voltage higher or lower than motor nameplate rating may cause overheating and serious motor damage. Check plant voltage conditions.

A separate manual starter with thermal overload protection device is recommended for those units that do not have motors with built in overload protection.

C.CASINGS

1.Cleaning

Periodic cleaning of casings is recommended to remove dirt, grease and corrosive substances that may injure ﬁnish. Rusted or corroded spots should be cleaned and repainted.

2.General Inspection

Tighten fan guard and motor bracket. Check fan for proper clearance, free rotation and ﬁrm connection to shaft. When servicing is complete, tag unit to indicate date of inspection, lubrication and cleaning.

WARNING

The equipment covered in this manual should be installed, maintained and serviced by a qualified technician.

NOTICE

For service contact your local qualified installation and service contractor or appropriate utility company.

D.COILS

1. Cleaning

Clean coil at least once a year, more often under unfavorable conditions. Unless coil is kept reasonably free of dirt, lint and grease, its original heating capacity will be reduced — possibly to a serious degree, and motor damage may result.

Two commonly used cleaning methods are:

a.Loosen dirt by brushing ﬁns on side where air enters coil and then turn on fan to blow dirt from unit.

b.Use high-pressure air hose to loosen dirt by blowing from side where air leaves coil (side adjacent to louvers on blow-through units (BH); side adjacent to fan on draw-through units (BV)). For thorough cleaning of coil, remove motor and fan and spray a mild alkaline cleaning solution over the coil. After a few minutes, follow by a hot water rinse. (A steam gun can be used for spraying cleaning solution and hot water.) Coils subjected to corrosive fumes should be checked and cleaned frequently.

2.Internal Corrosion Safeguards

Provide controlled water treatment -- don’t use excess of boiler compounds. Contact your boiler compound supplier for proper usage or the services of a water treatment laboratory. Periodic internal ﬂushing of the coils is recommended in areas where water supply is suspected of causing scale. Use an alkaline-chelant solution and introduce it at the main pump of the hydronic system. Flush thoroughly.

WARNING

Using inorganic or mineral acids such as muriatic (hydrochloric) acid, even though inhibited, may lead to severe damage, including corrosion and leakage.

De-aerate boiler feed-water (particularly if large amount of new water is used). Insure rapid continuous and adequate condensate drainage by properly sized and installed traps and piping. Check traps for sticking. Clean strainers ahead of traps. (When traps don’t work, condensate accumulates in unit heater coil; water hammer results.) Adequately vent each unit. Use low- pressure steam when possible.