Carrier 50RTG Coaxial Water Pressure Drop, Approximate Fluid Volume gal Per 100 Ft of Pipe

6.Open the return valve to send a pressure surge through the loop to purge any air pockets in the piping system.

7.A noticeable drop in fluid level will be seen in the flush cart tank. This is the only indication of air in the loop.

NOTE: If air is purged from the system while using a 10 in. PVC flush tank, only a 1 to 2 in. level drop will be noticed since liquids are incompressible. If the level drops more than this, flushing should continue since air is still being com- pressed in the loop. If level is less than 1 to 2 in., reverse the flow.

8.Repeat this procedure until all air is purged.

9.Restore power.

Antifreeze may be added before, during or after the flushing process. However, depending on when it is added in the process, it can be wasted. Refer to the Antifreeze section for more detail.

Loop static pressure will fluctuate with the seasons. Pres- sures will be higher in the winter months than during the warm- er months. This fluctuation is normal and should be considered when charging the system initially. Run the unit in either heat- ing or cooling for several minutes to condition the loop to a homogenous temperature.

When complete, perform a final flush and pressurize the loop to a static pressure of 40 to 50 psi for winter months or 15 to 20 psi for summer months.

After pressurization, be sure to remove the plug from the end of the loop pump motor(s) to allow trapped air to be discharged and to ensure the motor housing has been flooded. Be sure the loop flow center provides adequate flow through the unit by checking pressure drop across the heat exchanger. Compare the results to the data in Table 16.

Table 16 — 50RTG Coaxial Water Pressure Drop

UNIT		WATER TEMPERATURE (F)
	GPM	30		50	70	90
50RTG
			Pressure Drop (ft. H2O)
	4.0	3.1		2.8	2.8	2.8
03	6.0	6.1		5.3	5.3	5.3
	8.0	9.9		8.9	8.9	8.9
	10.0	14.3		12.9	12.9	12.9
	5.5	4.2		3.4	3.4	3.4
04	8.5	8.9		7.8	7.8	7.8
	11.5	14.8		13.2	13.2	13.2
	14.0	20.5		18.6	18.6	18.6
	7.0	8.1		5.3	5.3	5.3
05	11.0	16.9		11.2	11.2	11.2
	15.0	28.5		18.9	18.9	18.9
	18.0	38.8		25.6	25.6	25.6
	10.0	3.4		2.3	2.3	2.3
07	15.0	10.1		6.7	6.7	6.7
	20.0	16.0		10.7	10.7	10.7
	24.0	22.3		14.9	14.9	14.9
	11.0	4.5		3.5	3.5	3.5
08	17.0	9.4		8.1	8.1	8.1
	22.0	14.2		12.7	12.7	12.7
	27.0	20.0		18.2	18.2	18.2
	14.0	8.3		5.5	5.5	5.5
10	22.0	17.6		11.7	11.7	11.7
	30.0	29.4		19.7	19.7	19.7
	36.0	39.9		26.7	26.7	26.7
	17.0	4.8		3.2	3.2	3.2
12	25.0	9.4		6.0	6.0	6.0
	34.0	13.1		10.3	10.3	10.3
	40.0	22.0		13.5	13.5	13.5
	21.0	5.2		2.9	2.9	2.9
15	32.0	10.7		7.4	7.4	7.4
	42.0	17.4		11.6	11.6	11.6
	51.0	24.3		16.5	16.5	16.5
	31.0	10.6		6.4	6.4	6.4
20	47.0	21.2		13.1	13.1	13.1
	62.0	34.2		20.8	20.8	20.8
	74.0	46.2		28.0	28.0	28.0

Antifreeze — In areas where entering loop temperatures drop below 40 F or where piping will be routed through areas subject to freezing, antifreeze is needed.

Alcohols and glycols are commonly used as antifreeze agents. Freeze protection should be maintained to 15 F below the lowest expected entering loop temperature. For example, if the lowest expected entering loop temperature is 30 F, the leav- ing loop temperature would be 22 to 25 F. Therefore, the freeze protection should be at 15 F (30 F – 15 F = 15 F).

IMPORTANT: All alcohols should be pre-mixed and pumped from a reservoir outside of the building or introduced under water level to prevent fumes.

Calculate the total volume of fluid in the piping system. See Table 17. Use the percentage by volume in Table 18 to deter- mine the amount of antifreeze to use. Antifreeze concentration should be checked from a well mixed sample using a hydrome- ter to measure specific gravity.

FREEZE PROTECTION SELECTION — The 30 F FP1 fac- tory setting (water) should be used to avoid freeze damage to the unit.

Once antifreeze is selected, the JW3 jumper (FP1) should be clipped on the control to select the low temperature (anti- freeze 13 F) set point to avoid nuisance faults.

Table 17 — Approximate Fluid Volume (gal.)

per 100 Ft of Pipe

PIPE	DIAMETER (in.)			VOLUME (gal.)
Copper	1			4.1
	1.25			6.4
	1.5			9.2
Rubber Hose	1			3.9
Polyethylene	3/	IPS SDR11		2.8
	4			4.5
	1 IPS SDR11
	11/	4	IPS SDR11	8.0
	1/	IPS SDR11		10.9
	2			18.0
	2 IPS SDR11
	11/	4	IPS SCH40	8.3
	11/		IPS SCH40	10.9
		2
	2 IPS SCH40			17.0

LEGEND

IPS — Internal Pipe Size

SCH — Schedule

SDR — Standard Dimensional Ratio

NOTE: Volume of heat exchanger is approximately 1.0 gallon.

Table 18 — Antifreeze Percentages by Volume

	MINIMUM TEMPERATURE FOR
ANTIFREEZE		FREEZE PROTECTION (F)
	10		15	20	25
Methanol (%)	25		21	16	10
100% USP Food Grade	38		30	22	15
Propylene Glycol (%)

Cooling Tower/Boiler Systems — These systems typically use a common loop maintained at 60 to 90 F. The use of a closed circuit evaporative cooling tower with a secondary heat exchanger between the tower and the water loop is recom- mended. If an open type cooling tower is used continuously, chemical treatment and filtering will be necessary.

Ground Coupled, Closed Loop and Plateframe Heat Exchanger Well Systems — These systems al- low water temperatures from 30 to 110 F. The external loop field is divided up into 2 in. polyethylene supply and return lines. Each line has valves connected in such a way that upon system start-up, each line can be isolated for flushing using only the system pumps. Air separation should be located in the piping system prior to the fluid re-entering the loop field.

18