A
90° STD
B
90° LONG RAD
C
| 45° STD |
| A92498 |
Fig. |
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TABLE | |||
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TUBE SIZE OD | REFERENCE DIAGRAM IN FIG. 1 | ||
(IN.) | A | B | C |
5/8 | 1.6 | 1.0 | 0.8 |
3/4 | 1.8 | 1.2 | 0.9 |
7/8 | 2.0 | 1.4 | 1.0 |
2.6 | 1.7 | 1.3 | |
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NOTE: If total equivalent horizontal length is 100 ft or longer, both indoor and outdoor pistons must be increased 1 full piston size, in addition to changes required by Tables 6 and 7.
After finding appropriate change in piston size, add or subtract the change from original piston number. If piston size is decreased, round new piston number down to nearest common piston number found in Table 8. If piston size is increased, round new piston number up to nearest common piston number found in Table 8.
EXAMPLE:
An 042 size heat pump is 75 ft above an 042 size fan coil. The 042 size
To establish correct indoor piston size for a 75 ft vertical separation, refer to Table 6. For a 75 ft equivalent line length, the piston change is
80 – 5 = 75
Table 8 provides common piston sizes. In this instance, 75 is not listed, therefore round DOWN to next piston size, which would be 74.
To establish correct outdoor piston size for a 75 ft vertical separation, refer to Table 7. For a 75 ft equivalent line length, the piston change is +4. Therefore add 4 to the original outdoor piston size of 63:
63 + 4 = 67
Since 67 is listed in Table 8, that is the piston which should be used. If a 67 size piston were not listed, it would be necessary to round UP to next piston size.
TXVs may be used instead of pistons for
TABLE 6—CALCULATION OF INDOOR PISTON NO.
OUTDOOR UNIT ABOVE INDOOR
FT | PISTON CHANGE |
0 | |
OUTDOOR UNIT BELOW INDOOR | |
FT | PISTON CHANGE |
0 | |
+4 |
TABLE 7—CALCULATION OF OUTDOOR PISTON NO.
OUTDOOR UNIT ABOVE INDOOR
FT | PISTON CHANGE |
0 | |
+4 | |
+6 | |
+8 | |
+10 | |
OUTDOOR UNIT BELOW INDOOR | |
FT | PISTON CHANGE |
0 | |
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IV.
There are 2 types of