Trane UH-PRC001-EN manual Correction Factors for Propylene Glycol/Water, Selection Procedure, Step

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

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 (inTable 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

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.

Table SP-11 – Unit Heater HotWater Conversion Factors (AppliesToTables PD-1 - PD-5)

Ent.
Air												Entering WaterTemperature
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.

Correction Factors for Propylene Glycol/Water

When sizing equipment for systems that will utilize a propylene glycol solution, consider the following factors:

1.Heat transfer @180F with no increase in flow rate

Propylene

Glycol

20% solution	.97*
50% solution	.90*

Table SP-12 –Trane Unit Heater Nomenclature (AppliesToTables PD-1 - PD-5)

Abbreviations	Definitions
MBH	1000 BTU Per Hour
GPM	Gallons Per Minute
FT	FinalTemperature °F
PD-S.W.T.	Feet Of Water Pressure Drop - Standard WallTubes.
PD-H.W.T	Feet Of Water Pressure Drop - Heavy WallTubes

	Propylene		Propylene
2. GPM required @180F,	Glycol			Glycol
20°D (no correction to
pump curve)	1.10%	7. pH@50% by volume.		9.5
3. Pump head required		8. Freezing Point	55% by volume —
@180F w/increase in			50%	-28F
GPM	1.23%*		40%	-13F
4. Specific gravity			30%	+28F
			20%	+17F
(water = 1.0)	1.045-1.055*	**Compared to water
5. Pounds/Gallons@60F
(water = 8.3453
Pounds/Gallons)	8.77

20 UH-PRC001-EN