Hach sc200, Руководство пользователя

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S E L E C T I N G A U N I T H E A T E R F O R U S E W I T H H O T W A T E R
DESIGN CONDITIONS
— Heating load = 138 MBH
— Entering air temperature (EAT) = 70°F
— Entering water temperature (EWT)* = 220°F
— Water temperature drop (WTD) = 20°F
— Mounting height = 12 feet
— Spread required = 30 feet
— Standard horizontal projection unit required (model H).
SELECTING PROCEDURE
1 ) Calculate equivalent capacity at conditions of Table 8.
Capacity required
Equivalent capacity = —————————
Factor (Table 10)
138
= ——— = 130 MBH
1.06
From Table 8, choose the unit heater with this output, at
the condition 200°F EWT and 20°F WTD.
We select Cat. No. H-136 unit heater.
2) Calculate unit capacity at actual conditions.
Actual capacity = MBH (Table 8) x Factor (Table 10)
= 135.5 x 1.06 = 143.63 MBH
3) Calculate coil water flow (USGPM)
Actual BTUH 143,630
Water flow = ——————— = ———— = 14.36 USGPM
500 x WTD 500 x 20
4) Calculate coil water pressure drop (WPD).
USGPM (Actual)
WPD = WPD (Table 8) x —————————
USGPM (Table 8)
14.36
= 1.31 x ——— = 1.47 feet of water
13.55
5) Calculate final air temperature (FAT).
Actual BTUH
FAT = EAT + ———————
CFM x 1.08
143,630
= 70 + —————— = 123.84°F
2470 x 1.08
6) Determine mounting height and throw at actual conditions.
At Table 2 conditions (220°F EWT and 70°F EAT)
Mounting height = 14’ x 1.15 (Table 6) = 16.1 feet
Throw = 44’ x 1.15 = 50.6 feet
We can use this unit heater.
NOTE: See «GENERAL SELECTION» for application details
(page 3), and Table 7 for noise level.
( ) 2
( ) 2
E N T E R I N G W A T E R T E M P E R A T U R E — ° F
160 170 180 190 200 210 220 230 240 250 260 270 280 290
30 0.96 1.04 1.11 1.18 1.26 1.33 1.41 1.48 1.55 1.63 1.70 1.78 1.85 1.93
40 0.88 0.95 1.02 1.10 1.17 1.25 1.32 1.39 1.47 1.54 1.61 1.69 1.76 1.83
50 0.80 0.87 0.94 1.01 1.09 1.16 1.23 1.30 1.37 1.45 1.52 1.59 1.66 1.74
60 0.73 0.79 0.86 0.93 1.00 1.07 1.14 1.22 1.29 1.36 1.43 1.50 1.57 1.64
70 0.65 0.70 0.77 0.85 0.92 0.99 1.06 1.13 1.20 1.27 1.34 1.41 1.48 1.55
80 0.57 0.63 0.70 0.77 0.84 0.91 0.98 1.05 1.12 1.19 1.26 1.33 1.40 1.47
90 0.48 0.55 0.62 0.69 0.76 0.83 0.90 0.97 1.04 1.11 1.17 1.24 1.31 1.38
100 0.42 0.48 0.55 0.62 0.68 0.75 0.82 0.89 0.96 1.03 1.10 1.16 1.23 1.30
300 310 320 330 340 350 360 370 380 390 400
2.00 2.07 2.14 2.22 2.30 2.37 2.44 2.52 2.59 2.66 2.74
1.91 1.98 2.05 2.12 2.19 2.27 2.35 2.42 2.49 2.56 2.63
1.81 1.88 1.95 2.02 2.10 2.17 2.24 2.31 2.39 2.46 2.53
1.72 1.79 1.86 1.93 2.00 2.07 2.14 2.23 2.29 2.36 2.43
1.62 1.69 1.76 1.84 1.91 1.98 2.05 2.12 2.19 2.26 2.33
1.54 1.60 1.67 1.74 1.82 1.88 1.95 2.02 2.09 2.16 2.23
1.45 1.52 1.59 1.66 1.72 1.80 1.86 1.93 2.00 2.07 2.14
1.37 1.43 1.50 1.57 1.64 1.71 1.78 1.84 1.91 1.98 2.05
ENTERING
AIR
TEMP. °F
HOT WATER CORRECTION FACTORS
TABLE 10
*
For MBH at EWT other than those indicated in the tables, use 200°F MBH and multiply by factor in table 10. MBH obtained will be at USGPM of
200°F MBH used.
UNIT HEATERS