SERVICING
57
The following table shows refrigerant amount for every 5 feet of
line.
15 (Factory Charge)
165
272
272
242
20
168
275
275
245
25
171
278
278
248
30
174
281
281
251
35
177
284
284
254
40
180
287
287
257
45
183
290
290
260
50
186
293
293
263
55
189
296
296
266
60
192
299
299
269
65
195
302
302
272
70
198
305
305
275
75
201
308
308
278
80
204
311
311
281
85
207
314
314
284
90
210
317
317
287
95
213
320
320
290
100
216
323
323
293
105
219
326
326
296
110
222
329
329
299
115
225
332
332
302
120
228
335
335
305
125
231
338
338
308
130
234
341
341
311
135
237
344
344
314
140
240
347
347
317
145
243
350
350
320
150
246
353
353
323
155
249
356
356
326
160
252
359
359
329
165
255
362
362
332
170
258
365
365
335
175
261
368
368
338
180
264
371
371
341
185
267
374
374
344
190
270
377
377
347
195
273
380
380
350
200
276
383
383
353
Unit Tonnage
Actual Line Set Length
(ft.)
2-Ton
3-Ton
4-Ton
5-Ton
Refrigerant (Oz.)
Initial Refrigerant for Given Line Length
S-202 DUCT STATIC PRESSURES AND/OR STATIC PRESSURE
DROP ACROSS COILS
This minimum and maximum allowable duct static pressure for
the indoor sections are found in the specifications section.
Tables are also provided for each coil, listing quantity of air
(CFM) versus static pressure drop across the coil.
Too great an external static pressure will result in insufficient air
that can cause icing of the coil. Too much air can cause poor
humidity control and condensate to be pulled off the
indoor
coil
causing condensate leakage. Too much air can also cause motor
overloading and in many cases this constitutes a poorly designed
system.
S-203
AIR HANDLER EXTERNAL STATIC
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).
2. Measure the static pressure of the supply duct, (Positive Pres-
sure).
3. Add the two readings together.
TOTAL EXTERNAL STATIC
NOTE:
Both readings may be taken simultaneously and read di-
rectly on the manometer if so desired.
4. Consult proper table for quantity of air.
If external static pressure is being measured on a furnace to de-
termine airflow, supply static must be taken between the "A" coil
and the furnace.
TOTAL EXTERNAL STATIC