S-122 Reversing Valve Replacement; S-200 Checking External Static Pressure - Goodman GPH13 Service Instructions Manual

SERVICING
CAUTION
DO NOT ALLOW THE SLUDGE OR OIL TO CONTACT
THE SKIN, SEVERE BURNS MAY RESULT.
Suction Line Drier Clean-up Method
Discard at least twelve (12) inches of the suction line immedi-
ately out of the compressor stub due to burned residue and
contaminates.
1. Remove compressor discharge line strainer, liquid line
strainer and/or drier and capillary tubes from indoor and
outdoor coils.
2. Units with an expansion valve coil, remove the liquid line
drier and expansion valve.
3. Purge all remaining components with dry nitrogen or car-
bon dioxide until clean.
4. Install new components including liquid liner drier.
5. Install suction line drier.
6. Braze all joints, leak test, evacuate, and recharge system.
7. Start up the unit and record the pressure drop across the
cleanup drier.
8. Continue to run the system for a minimum of twelve (12)
hours and recheck the pressure drop across the drier. Pres-
sure drop should not exceed 6 - 8 PSIG.
9. Continue to run the system for several days repeatedly
checking pressure drop across the suction line drier. If the
pressure drop never exceeds the 6 - 8 PSIG, the drier must
be adequate and is trapping the contaminants and it is
permissible to leave it in the system.
10. If the pressure drop becomes greater, then it must be re-
placed and steps 5 through 9 repeated until it does not
exceed 6 - 8 PSIG.
NOTE: The cause for burnout MUST be determined and cor-
rected BEFORE the new compressor is started.

S-122 REVERSING VALVE REPLACEMENT

Remove the refrigerant charge from the system.
When brazing a reversing valve into the system, it is of ex-
treme importance that the temperature of the valve does not
exceed 250°F. at any time.
Wrap the reversing valve with a large rag saturated with water.
"Re-wet" the rag and thoroughly cool the valve after each braz-
ing operation of the four joints involved. The wet rag around the
reversing valve will eliminate conduction of heat to the valve
body when brazing the line connection.
The use of a wet rag sometimes can be a nuisance. There are
commercial grades of heat absorbing paste that may be sub-
stituted.
After the valve has been installed, leak test, evacuate and re-
charge.
S-200 CHECKING EXTERNAL STATIC
PRESSURE
The minimum and maximum allowable duct static pressure is
found in the Technical Information Manual.
Too great of an external static pressure will result in insuffi-
cient air that can cause icing of the coil, whereas too much air
can cause poor humidity control, and condensate to be pulled
off the evaporator coil causing condensate leakage. Too much
air can cause motor overloading and in many cases this con-
stitutes a poorly designed system. To determine proper air
movement, proceed as follows:
1. Using a draft gauge (inclined manometer) measure the static
pressure of the return duct at the inlet of the unit, (Negative
Pressure).
Total External Static
39