Omnizone™ Constant Volume Water-Cooled Heat Pump Maintenance

Date:

Cleaning Unit Exterior

• Unit exterior panels should be wiped down using a damp soft cloth or sponge with a mixture of warm water and a mild detergent.

Coil Cleaning

• Clean coils with a vacuum cleaner, fresh water, compressed air, or a bristle brush (not wire).

• Do not use high-pressure water or air—damage to fins may result.

• Back flush coil to remove debris.

• After cleaning, use a fin comb of the correct fin spacing when straightening mashed or bent coil fins.

Condensate Drains

• Clean the drain line and unit drain pan at the start of each cooling season.

• Check flow by pouring water into the drain.

Water-Cooled Condensers

• Isolate the supply and return water connections when removing piping to the condenser.

• Clean condensers with an inhibited hydrochloric acid solution. (The acid can stain hands and clothing and attack concrete, and, without inhibitor, can attack steel.

• Cover surroundings to guard against splashing. (Vapors from vent pipe are not harmful, but take care to prevent liquid from being carried over by gases.)

GRAVITY FLOW METHOD (FIG. 26)

• Do not add solution faster than the vent can exhaust the generated gases.

• When condenser is full, allow the solution to remain overnight; then drain the condenser and flush with clean water.

• Follow acid manufacturer’s instructions.

FORCED CIRCULATION METHOD (FIG. 27)

• Fully open the vent pipe when filling the condenser. The vent may be closed when the condenser is full and the pump is operating.

• Regulate the flow to the condenser with a supply line valve. If the pump is the non-overloading type, the valve may be fully closed while the pump is running

• For average scale deposit, allow the solution to remain in the condenser overnight.

• For heavy scale deposit, allow a full 24 hours.

• Drain the condenser and flush with clean water.

• Follow acid manufacturer’s instructions.

Fan Motor Lubrication

• Lubricate the fan motor(s) with SAE-20 (Society of Automotive Engineers) non-detergent electric oil.

To install sheaves on the fan or motor shaft:

• Isolate power to the unit.

• Remove side unit access panel(s).

• Remove any rust-preventive coating on the fan shaft.

• Make sure the shaft is clean and free of burrs. Add grease or lubricant to bore of sheave before installing.

• Mount sheave on the shaft; to prevent bearing damage, do not use excessive force.

ALIGNMENT

• Make sure that fan shafts and motor shafts are parallel and level.

Shaft Alignment

• Check shaft alignment by measuring the distance between the shafts at 3 or more locations. If the distances are equal, then the shafts are parallel.

Sheave Alignment

• To check the location of the fixed sheaves on the shafts, use a straightedge or a piece of string. If the sheaves are properly aligned, the string will touch them at the points indicated by the arrows in Fig. 28.

• Rotate each sheave a half revolution to determine whether the sheave is wobbly or the drive shaft is bent.

• Correct any misalignment.

• With sheaves aligned, tighten cap screws evenly and progressively.

• NOTE: There should be a 1/8-in. to 1/4-in. gap between the mating part hub and the bushing flange. If the gap is closed, the bushing is probably the wrong size.

• With taper-lock bushed hubs, be sure the bushing bolts are tightened evenly to prevent side-to-side pulley wobble.

• Check by rotating sheaves and rechecking sheave alignment.

• When substituting field-supplied sheaves for factory-supplied sheaves, only the motor sheave should be changed.

To change fan speeds from factory settings:

• Shut off unit power supply.

• Loosen nuts on the 4 carriage bolts in the mounting base. Using adjusting bolts and plate, slide the motor and remove the belt.

• Loosen movable-pulley flange setscrew.

• Screw the movable flange toward the fixed flange to increase speed, and away from the fixed flange to decrease speed. Increasing the fan speed increases the load on the motor. Do not exceed the maximum speed specified in Tables 2 and 3.

• Set the movable flange at nearest keyway of the pulley hub and tighten the setscrew. (See Tables 2 and 3 for speed change for each full turn of pulley flange.)

• Replace and tighten the belts (see Belt Tension Adjustment section).

• Restore power to the unit.

To align fan and motor pulleys:

• Loosen fan pulley setscrews.

• Slide fan pulley along fan shaft.

• Make angular alignment by loosening motor from mounting plate.

• Restore power to unit.

BELT TENSION ADJUSTMENT

• Using a gage, apply 4 lb of force to the center of the belt and adjust the tension until a deflection of 1/64 in. is achieved for every inch of shaft center distance. See Fig. 29.

• Ideal belt tension is the lowest value under which belt slip will not occur at peak load conditions.

Compressor Oil

• Operate the system at high evaporator temperature prior to oil recharge to assist oil return to the compressor(s) from other system components

• If necessary, recharge the system as shown in Table 32.