32
Flow Regulation — Flow regulation can be accom-
plished by two methods. Most water control valves have a flow
adjustment built into the valve. By measuring the pressure drop
through the unit heat exchanger, the flow rate can be deter-
mined. See Table 26. Adjust the water control valve until the
flow of 1.5 to 2 gpm is achieved. Since the pressure constantly
varies, two pressure gages may be needed in some
applications.
An alternative method is to install a flow control device.
These devices are typically an orifice of plastic material de-
signed to allow a specified flow rate that are mounted on the
outlet of the water control valve. Occasionally these valves
produce a velocity noise that can be reduced by applying some
back pressure. To accomplish this, slightly close the leaving
isolation valve of the well water setup.
Flushing — Once the piping is complete, units require final
purging and loop charging. A flush cart pump of at least 1.5 hp
is needed to achieve adequate flow velocity in the loop to purge
air and dirt particles from the loop. Flush the loop in both
directions with a high volume of water at a high velocity. Fol-
low the steps below to properly flush the loop:
1. Verify power is off.
2. Fill loop with water from hose through flush cart before
using flush cart pump to ensure an even fill. Do not allow
the water level in the flush cart tank to drop below the
pump inlet line to prevent air from filling the line.
3. Maintain a fluid level in the tank above the return tee to
avoid air entering back into the fluid.
4. Shutting off the return valve that connects into the flush
cart reservoir will allow 50 psig surges to help purge air
pockets. This maintains the pump at 50 psig.
5. To purge, keep the pump at 50 psig until maximum
pumping pressure is reached.
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, the level drop will only be 1 to 2 in. since
liquids are incompressible. If the level drops more than this,
flushing should continue since air is still being compressed 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
warmer months. This fluctuation is normal and should be con-
sidered when charging the system initially. Run the unit in
either heating 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 psig for winter months or
15 to 20 psig 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 26.
Table 26 — Coaxial Water Pressure Drop
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
leaving loop temperature would be 22 to 25 F. Therefore, the
freeze protection should be at 15 F (30 F – 15 F = 15 F).
Calculate the total volume of fluid in the piping system. See
Table 27. Use the percentage by volume in Table 28 to
determine the amount of antifreeze to use. Antifreeze concen-
tration should be checked from a well mixed sample using a
hydrometer to measure specific gravity.
FREEZE PROTECTION SELECTION — The 30 F FP1
factory 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.
Cooling Tower/Boiler Systems — These systems typ-
ically use a common loop temperature maintained at 60 to 90 F.
Carrier recommends using a closed circuit evaporative cooling
tower with a secondary heat exchanger between the tower and
WARNING
To avoid possible injury or death due to electrical shock,
open the power supply disconnect switch and secure it in
an open position before flushing system.
50PC UNIT
SIZE
gpm L/s
PRESSURE DROP, psi (kPa)
30 F
(-1 C)
50 F
(10 C)
70 F
(21 C))
90 F
(32 C)
006
0.75 0.05 0.5 (3.7) 0.3 (2.3) 0.2 (1.6) 0.2 (1.6)
1.1 0.07 0.8 (5.3) 0.5 (3.5) 0.4 (2.7) 0.3 (2.2)
1.5 0.09 1.3 (8.8) 0.9 (6.1) 0.7 (4.8) 0.6 (4.0)
009
1.1 0.07 1.3 (9.0) 0.6 (4.4) 0.4 (2.8) 0.3 (1.9)
1.8 0.11 2.1 (14.1) 1.4 (9.4) 1.1 (7.4) 0.9 (6.2)
2.3 0.14 3.5 (24.3) 2.6 (17.9) 2.1 (14.7) 1.8 (12.7)
012
1.5 0.09 1.9 (12.8) 1.1 (7.6) 0.8 (5.3) 0.6 (4.1)
2.3 0.15 3.6 (25.0) 2.6 (17.8) 2.1 (14.3) 1.8 (12.1)
3.0 0.19 6.7 (46.1) 5.0 (34.3) 4.1 (28.3) 3.6 (24.5)
015
1.9 0.12 1.0 (6.9) 0.6 (4.4) 0.5 (3.4) 0.4 (2.8)
2.8 0.18 1.8 (12.4) 1.4 (9.3) 1.1 (7.6) 1.0 (6.9)
3.8 0.24 3.3 (22.7) 2.5 (17.5) 2.1 (14.7) 1.9 (13.1)
018
2.3 0.14 2.1 (14.5) 1.4 (9.9) 1.1 (7.6) 0.9 (6.2)
3.4 0.21 3.4 (23.4) 2.6 (17.6) 2.1 (14.7) 1.8 (12.4)
4.5 0.28 5.9 (40.6) 4.6 (31.5) 3.9 (26.9) 3.4 (23.4)
024
3.0 0.19 2.2 (15.2) 1.7 (11.6) 1.4 (9.6) 1.2 (8.3)
4.5 0.28 4.0 (27.6) 3.2 (22.2) 2.8 (19.3) 2.5 (17.2)
6.0 0.38 7.2 (49.6) 5.9 (40.6) 5.2 (35.8) 4.7 (32.4)
030
3.8 0.24 1.3 (9.0) 0.9 (6.1) 0.7 (4.8) 0.6 (4.1)
5.6 0.35 2.3 (15.8) 1.8 (12.5) 1.5 (10.3) 1.4 (9.6)
7.5 0.47 4.2 (28.9) 3.4 (23.2) 2.9 (20.0) 2.6 (17.9)
036
4.5 0.28 1.8 (12.4) 1.4 (9.6) 1.2 (8.3) 1.0 (6.9)
6.8 0.43 3.1 (21.4) 2.4 (16.8) 2.1 (14.7) 1.9 (13.1)
9.0 0.57 5.4 (37.2) 4.4 (30.0) 3.8 (26.2) 3.4 (23.4)
042
5.3 0.33 2.3 (15.8) 1.8 (12.1) 1.5 (10.3) 1.3 (9.0)
7.9 0.50 4.3 (29.6) 3.5 (24.2) 3.1 (26.4) 2.8 (19.3)
10.5 0.66 7.9 (54.4) 6.5 (44.8) 5.7 (39.3) 5.2 (35.8)
048
6.0 0.38 1.8 (12.4) 1.5 (10.1) 1.3 (9.0) 1.2 (8.3)
9.0 0.57 3.4 (23.4) 3.0 (20.4) 2.7 (18.6) 2.6 (17.9)
12.0 0.76 6.2 (42.7) 5.5 (37.9) 5.1 (35.1) 4.8 (35.1)
060
7.5 0.47 3.4 (23.4) 2.8 (19.2) 2.4 (16.5) 2.2 (15.2)
11.3 0.71 6.8 (46.9) 5.9 (40.8) 5.4 (37.2) 5.0 (34.5)
15.0 0.95 12.6 (86.8) 11.1(76.8) 10.3(71.0) 9.6 (66.1)
IMPORTANT: All alcohols should be pre-mixed and
pumped from a reservoir outside of the building or
introduced under water level to prevent fuming.
