Heatcraft Refrigeration Products H-IM-CU Unit Cooler Piping, Evap, Line Sizing, Pipe size example

Unit Cooler Piping

Pipe size example:

Given: -10°F Freezer with one system having (2) evaporators

•One condensing unit rated at 24,000 BTUH’s @ -20°F SST R404A refrigerant.

•Two evaporators each rated at 12,000 BTUH’s @ 10°F TD.

•100 feet of actual line run between condensing unit to first evaporator and 20 feet of actual line run between the first evaporator and the second evaporator (see figure below).

How to figure line sizes:

1.Determine equivalent line run = actual run + valves and fitting allowances.

2.Use Line Sizing Tables to size lines.

3.Note any special considerations.

Evap. 2 Evap. 1

Fittings in this system:

•(6) 90° elbows in main line plus a 90° turn through a tee.

•(5) addtional 90° elbows to first evaporator.

•(4) additional 90° elbows to second evaporator.

Determine line size 1 (main line from condensing unit):

1.Main line from the condensing unit to be sized for the total capacity (balance) of the whole system of 24,000 BTUH’s (Table 8).

2.Refer to 24,000 @100 feet at -20°F SST R404A on the chart. You will find the suction line to be 1-3/8" and 1/2" liquid line.

3.Refer to Table 5. For every 1-3/8" 90° elbow you must add 4 equivalent feet of pipe and 2.5 equivalent feet of pipe for each 1-3/8" tee.

Therefore, total equivalent line run =

Actual line run		100 feet
+ (6)	1-3/8" elbows @ 4'	24 feet
+ (1)	1-3/8" tee @ 2.5'	2.5 feet
Total equivalent line run		126.5 feet

4.Refer to Table 8. For 126.5 total equivalent feet, the suction line size should be 1-3/8" and the liquid line stays at 1/2" line.

Note: The gray shaded areas on Table 8. For 24,000 BTUH’s, the maximum suction riser is 1-1/8" to insure proper oil return and pressure drop from the bottom p-trap to the top p-trap.

Determine line size 2 (evaporators):

1.Line sizing to each evaporator is based on 12,000 BTUH’s and equivalent run from condensing unit. First evaporator has an 105 ft. run and the second evaporator has a 120 ft. run.

2.Table 8 indicates 1-1/8" suction for the first evaporator and indicates 1-1/8" suction for the second evaporator.

3.Refer to Table 5. Each 1-1/8" 90° elbow adds 3 equivalent feet of pipe. Each 90° turn through a 1-1/8" tee adds 6 equivalent feet.

4.	Actual line run (evap 1)		105 feet
	+ (5)	1-1/8" elbows @ 3'	15 feet
	+ (1)	90° turn through tee @ 6'	6 feet
	Total equivalent line run		126 feet
	Actual line run (evap 2)		120 feet
	+ (4)	1-1/8" elbows @ 3'	12 feet
	Total equivalent line run		132 feet

5.Table 8 indicates 1-1/8" suction line and 3/8" liquid line from main line to both evaporators.

Line Sizing

The following Tables 7 and 8 indicate liquid lines and suction lines for all condensing units for R22, R404A, and R507.

When determining the refrigerant line length, be sure to add an allowance for fittings. See Table 5. Total equivalent length of refrigerant lines is the sum of the actual linear footage and the allowance for fittings.

Table 3. Weight of Refrigerants in Copper Lines During Operation (Pounds per 100 lineal feet of type "L" tubing)

Line Size O.D.	Refrigerant	Liquid Line	Hot Gas Line		Suction Line at Suction Temperature
(Inches)				-40˚F	-20˚F	0˚F	+20˚F	+40˚F
3/8	22	3.9	0.22	0.02	0.03	0.04	0.06	0.08
	R507, 404A	3.4	0.31	0.03	0.04	0.06	0.09	0.13
1/2	22	7.4	0.41	0.03	0.05	0.07	0.11	0.15
	R507, 404A	6.4	0.58	0.04	0.07	0.13	0.16	0.24
5/8	22	11.8	0.65	0.05	0.08	0.12	0.17	0.25
	R507, 404A	10.3	0.93	0.07	0.11	0.17	0.25	0.35
7/8	22	24.4	1.35	0.10	0.16	0.24	0.36	0.51
	R507, 404A	21.2	1.92	0.15	0.23	0.37	0.51	0.72
1-1/8	22	41.6	2.30	0.17	0.28	0.42	0.61	0.87
	R507, 404A	36.1	3.27	0.26	0.39	0.63	0.86	1.24
1-3/8	22	63.5	3.50	0.27	0.42	0.64	0.93	1.33
	R507, 404A	55.0	4.98	0.40	0.58	0.95	1.32	1.87
1-5/8	22	90.0	4.96	0.37	0.59	0.90	1.33	1.88
	R507, 404A	78.0	7.07	0.56	0.82	1.35	1.86	2.64
2-1/8	22	156	8.61	0.65	1.03	1.57	2.30	3.26
	R507, 404A	134	12.25	0.98	1.43	2.35	3.23	4.58
2-5/8	22	241	13.70	1.01	1.59	2.42	3.54	5.03
	R507, 404A	209	18.92	1.51	2.21	3.62	5.00	7.07
3-1/8	22	344	18.95	1.44	2.28	3.45	5.05	7.18
	R507, 404A	298	27.05	2.16	3.15	5.17	7.14	9.95
3-5/8	22	465	25.60	1.94	3.08	4.67	6.83	9.74
	R507, 404A	403	36.50	2.92	4.25	6.97	19.65	13.67
4-1/8	22	605	33.40	2.53	4.01	6.08	8.90	12.70
	R507, 404A	526	47.57	3.80	5.55	9.09	12.58	17.80

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