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44 Packaged Heat Pump • WC-IOM-7
Maintenance
• With the unit running, check and record the: ambient temperature;
compressor suction and discharge pressures (each circuit); superheat (each
circuit);
Record this data on an “operator’s maintenance log” like the one shown in
Table 7 on page 46. If the operating pressures indicate a refrigerant shortage,
measure the system superheat. For guidelines, refer to the “Compressor Start-
Up” section.
Note: Do Not release refrigerant to the atmosphere! If adding or removing
refrigerant is required, the service technician must comply with all federal,
state and local laws.
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.
Coil Cleaning
Regular coil maintenance, including annual cleaning, enhances the unit’s
operating efficiency by minimizing: compressor head pressure and amperage
draw; evaporator water carryover; fan brake horsepower, due to increase static
pressure losses; airflow reduction.
At least once each year, or more often if the unit is located in a “dirty”
environment, clean the evaporator and condenser coils using the instructions
outlined below. Be sure to follow these instructions as closely as possible to
avoid damaging the coils.
To clean refrigerant coils, use a soft brush and a sprayer (either a garden pump-
up type or a high-pressure sprayer). A high-quality detergent is also required;
suggested brands include “SPREX A.C.”, “OAKITE 161”, “OAKITE 166” and
“COILOX”. If the detergent selected is strongly alkaline (ph value exceeds 8.5),
add an inhibitor.
1. Remove enough panels from the unit to gain access to the coil. Remove the
access panel from the roof located next to the rear condenser fan.
2. Protect all electrical devices such as motors and controllers from any over
spray.
3. Straighten any bent coil fins with a fin comb.
4. Mix the detergent with water according to the manufacturer’s instructions. If
desired, heat the solution to 150° F maximum to improve its cleansing
capability.