22
Table 9 - Typical unit operating pressures and temperatures
Entering Water
Cooling
Heating
water
flow
Suction
Discharge
Super-
Sub-
Water temp. Air temp.
Suction
Discharge
Super-
Sub-
Water temp. Air temp.
temp.
l/s per kW
pressure
pressure
heat
cooling
rise
drop
pressure
pressure
heat
cooling
drop
rise
°
C
kPa
kPa
K
K
K
K
kPa
kPa
K
K
K
K
-1
0.027
225-254
269-314
14-22
7-11
12-13
12-14
102-117
499-556
7- 9
1-2
4-5
8-11
0.041
222-251
239-284
14-22
6-10
7- 9
12-14
111-129
514-571
7- 9
1-2
3-4
9-12
0.054
219-248
209-254
14-22
6- 9
3- 6
12-14
120-138
529-586
7- 9
1-2
2-3
9-12
10
0.027
225-254
374-463
7-11
6-10
11-13
11-14
150-179
538-628
6- 9
1-3
6-7
13-16
0.041
222-251
359-425
7-11
5- 9
7- 8
11-14
158-185
553-643
6- 9
1-3
4-5
13-17
0.054
219-248
344-413
7-11
4- 8
4- 7
11-14
164-194
568-658
6- 9
1-3
3-4
14-17
21
0.027
225-254
535-592
5- 9
4- 8
11-12
11-13
212-245
613-688
8-11
1-3
8-9
16-19
0.041
222-251
502-556
5- 9
4- 7
7- 9
11-13
218-254
628-712
8-11
1-3
5-6
17-21
0.054
219-248
472-523
5- 9
4- 7
4- 7
11-13
227-263
643-724
8-11
1-3
3-4
17-21
32
0.027
225-254
685-750
5- 9
4- 8
10-12
9-13
254-284
658-777
10-16
1-3
8-9
18-22
0.041
222-251
652-721
5- 9
4- 7
6- 8
9-13
269-299
673-792
10-16
1-3
6-7
18-23
0.054
219-248
622-688
5- 9
4- 7
3- 6
9-13
284-314
688-807
10-16
1-3
4-5
19-23
43
0.027
231-260
837-957
4- 8
6-14
9-11
8-11
0.041
228-257
807-927
4- 8
6-13
5- 7
8-11
0.054
225-254
777-897
4- 8
6-12
3- 6
8-11
Notes:
1.
Based on nominal 54 l/s per kW air flow and 21
°
C entering air temperature heating and 26.7/19.4
°
C entering air temperature cooling.
2.
Cooling air and water numbers can vary greatly with changes in humidity.
3.
Subcooling is based upon the head pressure at compressor service port.
Table 10 - 50RHE tube-in-tube water pressure drop
50RHE
Flow
Pressure drop, kPa
l/s
0
°
C
10
°
C
20
°
C
30
°
C
006
0.047
6.0
5.4
5.1
4.8
0.071
8.4
7.8
7.2
6.9
0.095
14.1
13.2
12.0
11.7
009
0.071
8.1
7.5
6.9
6.6
0.107
12.0
11.1
10.5
9.9
0.139
23.9
22.4
20.9
20.0
012
0.095
19.1
17.9
16.7
16.1
0.145
41.3
38.9
36.2
34.7
0.189
66.1
61.9
57.7
55.0
015
0.114
16.7
15.5
14.7
14.1
0.164
32.6
30.5
28.7
27.2
0.221
55.9
52.3
48.7
46.3
019
0.142
12.9
12.0
11.1
10.8
0.215
23.0
21.5
20.3
19.1
0.284
45.4
42.5
39.8
37.7
024
0.189
13.8
12.6
11.7
11.4
0.284
28.7
26.9
25.1
23.9
0.379
47.8
44.9
41.9
39.8
030
0.237
9.9
9.0
8.4
8.1
0.347
17.0
15.8
14.7
14.1
0.473
26.9
25.4
23.6
22.4
036
0.284
7.8
7.2
6.9
6.6
0.426
15.0
13.8
12.9
12.3
0.568
23.9
22.4
20.9
20.0
042
0.331
9.9
9.3
8.7
8.4
0.498
19.7
18.5
17.0
16.4
0.663
31.1
29.3
27.5
26.0
048
0.379
14.1
13.2
12.3
11.7
0.568
26.9
25.4
23.6
22.4
0.757
44.0
41.0
38.3
36.5
060
0.473
33.5
31.4
29.3
27.8
0.713
58.3
54.4
50.8
48.4
0.947
88.5
82.8
77.1
73.3
6.6 - Flushing
Once the piping is complete, units require final purging and loop
charging. A flush cart pump of at least 1.12 kW 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. Follow the steps below
to flush the loop properly:
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 345 kPa surges to help purge air
pockets. This maintains the pump at 345 kPa.
5.
To purge, keep the pump at 345 kPa 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 254 mm
PVC flush tank, the level drop will only be 25 to 51 mm 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 25 to 51 mm, reverse the flow.
8.
Repeat this procedure until all air is purged.
9.
Restore power.
Anti-freeze 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 anti-freeze section for more detail.
Loop static pressure will fluctuate with the seasons. Pressures will
be higher in the winter months than during the warmer months.
This fluctuation is normal and should be considered 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 pressurise the loop to
a static pressure of 275 to 345 kPa for winter months or 105 to
135 kPa for summer months.
After pressurisation, 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 centre provides adequate flow through the unit by
checking pressure drop across the heat exchanger. Compare the
results to the data in Table 10.
