5-565.1
11
unit installation
table 11.1 - cooling coil Performance limits
8. Use a vacuum pump to evacuate the coil and any
interconnecting piping that has been open to atmosphere.
Measure the vacuum in the piping using a micron gauge
located as far from the pump as possible (the vacuum at
the pump will be greater than the rest of the system).
Evacuate the coil to 500 microns or less then close the
valve between the pump and the system. If the vacuum
holds to 500 microns or less for one minute, the system
is ready to be charged or refrigerant pumped down in
another portion of the system can be opened to the coil.
A steady rise in microns would indicate that moisture is still
present and that the coil should be further vacuumed until
the moisture has been removed.
9. Failure to obtain a high vacuum is indicative of a great
deal of moisture or a small leak. Break the vacuum with
a charge of dry nitrogen or other suitable gas and recheck
for leaks (soapy water works well). If no leaks are found,
continue vacuuming the coil until the desired vacuum is
reached.
10. All field piping must be self-supporting.
chilled fluid Piping
To prevent noise within a system, an air vent is necessary to
bleed off the accumulated air in the system. The vent should be
located on the top of the inlet manifold where the air collects.
This vent should be opened twice a year. Air in the system will
generate noise and may cause water hammer than can damage
the joints of the piping and the cooling coil.
The outlet manifold should have a drain installed on the bottom
of the manifold to allow for periodic flushing of the system to
remove sediments and corrosion products from the cooling
coil. This drain should be opened to allow some fluid to drain
twice a year. Check coloration and viscosity of the effluent for
indications of corrosion in the system. The lines between the
unit and the structure should be insulated to prevent freezing of
the water.
figure 11.1 - general chilled fluid Piping
1. Once installed, the coil should be pressurized to 100 psig
with dry nitrogen or other suitable gas. The coil should be
left pressurized for a minimum of 10 minutes. If the coil
holds the pressure, the hook-up can be considered leak
free. If the pressure drops by 5 psig or less re-pressurize
the coil and wait another 10 minutes. If the pressure drops
again, there is more than likely one or more small leaks
which should be located and repaired. Pressure losses
greater than 5 psig would indicate a larger leak that should
be isolated and repaired. If the coil itself is found to be
leaking, contact your local factory representative.
2. All field brazing and welding should be performed using
high quality materials and an inert gas purge (such as
nitrogen) to reduce oxidation of the internal surface of
the coil.
3. All field piping must be self supporting. System piping
should be flexible enough to allow for thermal expansion
and contraction of the coil.
dX - single circuit dX - dual circuit
chilled Water
max. cooling tons
② ③
max coil area max coil area max coil area
dX
chilled
cfm
➀
(sq. ft.) cfm
➀
(sq. ft) cfm
➀
(sq. ft.)
coils
Water coils
75
1891
3.44
1707
3.10
1676
3.05
609
④
9.38
10.56
100
2206
4.01
2048
3.72
2011
3.66
741
⑤
11.43
12.62
125
2206
4.01
2048
3.72
2011
3.66
926
11.43
12.62
150
2521
4.58
2416
4.39
2372
4.31
1111
13.42
14.77
175
2521
4.58
2416
4.39
2372
4.31
1296
13.42
14.77
200
3352
6.09
3165
5.76
3214
5.84
1481
18.12
19.28
225
3352
6.09
3165
5.76
3214
5.84
1667
18.12
19.28
250
3724
6.77
3538
6.43
3592
6.53
1852
20.24
21.33
300
3724
6.77
3538
6.43
3592
6.53
2222
20.24
21.33
350
5214
9.48
4996
9.08
5073
9.22
2593
27.26
29.25
400
5214
9.48
4996
9.08
5073
9.22
2963
27.26
29.25
➀
Based on 550 feet per minute (FPM) coil face velocity.
➁
1 Ton = 12,000 Btu/Hr
➂
Based on 95°F Entering Dry Bulb, 75°F Entering Wet Bulb.
➃
Model Size 75 CFM listed for Chilled Water - DX Single Circuit CFM minimum is 688 and DX Dual Circuit CFM min is 621.
➄
Model Size 100 CFM listed for Chilled Water - DX Single Circuit CFM minimum is 802 and DX Dual Circuit CFM min is 745.
model
size
min
cfm
(all units)
Air Vent
Gate Valve
Tee
Vent Plug
Re
turn
Air F
low
S
up
pl
y
Dirt Leg
Cap
Union
Drain Plug
