Bryant R-22 Fitting Losses in Equivalent FT, Example, Calculation of Indoor Piston no

A

90° STD

B

90° LONG RAD

C

	45° STD		A92498
Fig. 3—Tube Bend Losses
TABLE 5—FITTING LOSSES IN EQUIVALENT FT
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
1-1/8	2.6	1.7	1.3

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.

—7—

EXAMPLE:

An 042 size heat pump is 75 ft above an 042 size fan coil. The 042 size heat-pump presale literature specifies a size 80 indoor piston and size 63 outdoor piston.

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 -5. Therefore subtract 5 from the original indoor piston size of 80:

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 indoor-metering devices. Some fan coils are equipped with a hard-shutoff, bi-flow TXV standard, and no change is required. When sizing an accessory TXV for long-line applications, TXV should be the same nominal tonnage as outdoor unit. Refer to presale literature for kit part numbers.

TABLE 6—CALCULATION OF INDOOR PISTON NO.

OUTDOOR UNIT ABOVE INDOOR

FT	PISTON CHANGE
0-25	0
26-50	-3
51-75	-5
76-100	-7
101-125	-9
126-150	-10
OUTDOOR UNIT BELOW INDOOR
FT	PISTON CHANGE
0-25	0
26-50	+4

TABLE 7—CALCULATION OF OUTDOOR PISTON NO.

OUTDOOR UNIT ABOVE INDOOR

FT	PISTON CHANGE
0-50	0
51-75	+4
76-100	+6
101-125	+8
126-150	+10
OUTDOOR UNIT BELOW INDOOR
FT	PISTON CHANGE
0-50	0

IV. LIQUID-LINE SOLENOID AND TUBING CONFIGU- RATION

There are 2 types of liquid-line solenoids: 1 for single-flow applications and the other for bi-flow applications. The purpose of having 2 solenoids is to minimize the valve internal-pressure drop in accordance with refrigerant flow direction and liquid migration to the compressor. The bi-flow solenoid is designed to have minimal refrigerant-pressure drop in either flow direction, which makes it suitable for heat pump usage. Refer to Table 9 for liquid-line solenoid kit part numbers.