Trane UH-PRC001-EN Easy Installation Manual Download Page 20

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UH-PRC001-EN

Selection
Procedure

Step 4.
Determine the pressure drop at 6.53
GPM. Pressure drops are cataloged for
both standard wall (SWT) and heavy
wall. (HWT) tube coils. In this example, if
a SWT coil is selected the pressure drop,
by interpolation is 2.38 feet of water.

Step 5.
Calculate the final air temperature

F.T. = E.A.T. + Btu/hr

CFM x 1.085

= 70 + 96000 = 70 + 53.2 = 123.2°

1661 x 1.085

Note:
If a constant water temperature drop is desired, apply the conversion factor to the WTD and to the desired MBH and enter 200° EWT column at these conditions. Select the unit which will
provide the equivalent MBH at the adjusted WTD. The GPM can then be interpolated from the table at the adjusted WTD. To determine the actual capacity at operating conditions proceed as
outlined in example #2.
If a constant GPM is desired, enter the 200° EWT column at the given or calculated GPM. Select the unit which will provide the equivalent MBH at this GPM. To determine the actual capacity
at operating conditions in this case proceed as outlined in example #1.

Example 2
Determine the capacity of a Model 336P
unit heater operating at 180° (EWT), 100°
(EAT) and 15° (WTD).
Step 1.
Find conversion factor (in Table SP-11)
= 0.546

Step 2.
Adjust the water temperature drop

Adj. WTD = 15 = 27.5°

.546

Step 3.
Multiply the MBH (interpolated) at
27.5° WTD, 200° EWT and 60° EAT by the
factor to obtain the MBH at desired
conditions.

0.546 x 224.9 = 123.0 MBH

Step 4.
WTD

= 27.5 x 0.546 = 15°

Step 5.

GPM = Btu/hr = 123,000 = 16.9

485xWTD

(485)(15)

Step 6.
Pressure drop interpolated at 27.5° WTD
for a SWT coil is 1.82 feet of water.

Step 7.
Calculate final temperature

F.T. = E.A.T. + Btu/hr

CFM x 1.085

= 100°

+ 123,000 = 121.8°

5210 x 1.085

Table SP-11 – Unit Heater Hot Water Conversion Factors (Applies To Tables PD-1 - PD-5)

Ent.
Air

Entering Water Temperature

Temp.

160

170

180

190

200

210

220

230

240

250

260

270

280

290

300

310

320

330

340

350

360

370

380

390

400

30 .962 1.036 1.110 1.182 1.259 1.331 1.408 1.482 1.554 1.627 1.702 1.780 1.850 1.925 2.000 2.070 2.142 2.220 2.295 2.370 2.440 2.515 2.590 2.660 2.735
40 .880 .954 1.024 1.100 1.171 1.249 1.318 1.391 1.468 1.539 1.612 1.686 1.759 1.831 1.909 1.976 2.048 2.120 2.193 2.268 2.348 2.417 2.488 2.560 2.632
50 .795 .869 .940 1.011 1.085 1.158 1.230 1.301 1.374 1.448 1.520 1.590 1.664 1.735 1.809 1.882 1.953 2.024 2.095 2.168 2.242 2.312 2.388 2.459 2.530
60 .715 .785 .859 .929 1.000 1.071 1.141 1.215 1.285 1.359 1.429 1.500 1.571 1.642 1.715 1.785 1.858 1.930 2.000 2.070 2.140 2.215 2.285 2.360 2.430
70 .634 .704

.774 .845 .917 .988 1.058 1.129 1.200 1.270 1.340 1.410 1.482 1.552 1.622 1.694 1.764 1.838 1.907 1.976 2.045 2.116 2.188 2.258 2.332

80 .568 .628 .698 .768 .838 .908 .978 1.048 1.118 1.188 1.258 1.328 1.398 1.468 1.538 1.604 1.674 1.742 1.815 1.884 1.952 2.020 2.091 2.162 2.230
90 .484 .552 .622 .690 .760 .829 .898 .967 1.036 1.106 1.173 1.244 1.311 1.380 1.450 1.515 1.585 1.655 1.723 1.795 1.862 1.930 1.998 2.067 2.137

100

.410 .478 .546 .615 .684 .753 .820 .889 .957 1.025 1.095 1.161 1.230 1.300 1.368 1.433 1.499 1.569 1.638 1.705 1.776 1.843 1.910 1.977 2.046

Apply to the 200 F entering water capacities only.

Table SP-12 – Trane Unit Heater Nomenclature (Applies To Tables PD-1 - PD-5)

Abbreviations

Definitions

MBH

1000 BTU Per Hour

GPM

Gallons Per Minute

Final Temperature °F

PD-S.W.T.