Carrier 39S handleiding
Handleiding
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Following the piping diagrams in Fig. 51-55, make all connections
while observing the following precautions:
• Install a drip line and trap on the pressure side of the inlet
control valve. Connect the drip line to the return line
downstream of the return line trap.
• To prevent scale or foreign matter from entering the con-
trol valve and coil, install a 3/32 in. mesh strainer in the
steam supply line upstream from the control valve.
• Provide air vents for the coils to eliminate
non-condensable gases.
• Select a control valve according to the steam load, not the
coils supply connection size. Do not use an oversized con-
trol valve.
• Do not use bushings that reduce the size of the header re-
turn connection. The return connection should be the same
size as the return line and reduced only at the downstream
trap.
• To lift condensate above the coil return line into overhead
steam mains, or pressurized mains, install a pump and re-
ceiver between the condensate trap and the pressurized
main. Do not try to lift condensate with modulating or on-
and-off steam control valves. Use only 15-degree check
valves, as they open with a lower water head. Do not use
45-degree or vertical-lift check valves.
• Use float and thermostatic traps. Select the trap size ac-
cording to the pressure difference between the steam sup-
ply main and the return main.
• Load variations can be caused by uneven inlet air distribu-
tion or temperature stratification.
• Drain condensate out of coils completely at the end of the
heating season to prevent the formation of acid.
Coil Freeze-Up Protection
WATER COILS
If a chilled water coil is applied with outside air, provisions must
be made to prevent coil freeze-up. Install a coil freeze-up thermo-
stat to shut down the system if any air temperature below 36°F is
encountered entering the water coil. Follow thermostat manufac-
turer’s instructions.
When a water coil is applied downstream of a direct-expansion
(DX) coil, a freeze-up thermostat must be installed between the
DX and water coil and electrically interlocked to turn off the cool-
ing to prevent freeze-up of the water coil.
For outdoor-air application where intermittent chilled water coil
operation is possible, one of the following steps should be taken:
• Install an auxiliary blower heater in cabinet to maintain
above-freezing temperature around coil while unit is shut
down.
• Drain coils and fill with an ethylene glycol solution suit-
able for the expected cold weather operation. Shut down
the system and drain coils. See Service section, Winter
Shutdown.
STEAM COILS
When used for preheating outdoor air in pressure or vacuum sys-
tems, an immersion thermostat to control outdoor-air damper and
fan motor is recommended. This control is actuated when steam
supply fails or condensate temperature drops below an established
level, such as 120 to 150°F. A vacuum breaker should also be used
to equalize coil pressure with the atmosphere when steam supply
throttles close. Steam should not be modulated when outdoor air is
below 40°F.
On low-pressure and vacuum steam-heating systems, the thermo-
stat may be replaced by a condensate drain with a thermal ele-
ment. This element opens and drains the coil when condensate
temperature drops below 165°F. Note that condensate drains are
limited to 5 psig pressure.
INNER DISTRIBUTING TUBE STEAM COILS
The inner distributing tube (IDT) steam coil used in the 39S
air-handling units has an inner tube pierced to facilitate the distri-
bution of the steam along the tube's length. The outer tubes are ex-
panded into plate fins. The completed assembly includes the sup-
ply and condensate header and side casings which are built to slant
the fin/tube bundle back toward the condensate header. The slant-
ing of the assembly ensures that condensate will flow toward the
drains. This condensate must be removed through the return pip-
ing to prevent premature failure of the coil. The fin/tube bundle is
slanted vertically for horizontal airflow coils, and horizontally for
vertical airflow coils.
IDT Steam Coil Piping
The following piping guidelines will contribute to efficient coil
operation and long coil life:
1. Use full size coil outlets and return piping to the steam trap.
Do not bush return outlet to the coil. Run full size to the trap,
reduce at the trap.
2. Use float and thermostatic (F and T) traps only for conden-
sate removal. Trap size selection should be based on the dif-
ference in pressure between the steam supply main and the
condensate return main. It is good practice to select a trap
with 3 times the condensate rating of the coil to which it is
connected.
3. Use thermostatic traps for venting only.
4. Use only 1/2 in., 15-degree swing check valves installed hori-
zontally, piped open to atmosphere, and located at least 12 in.
above the condensate outlet. Do not use 45-degree, vertical
lift and ring check valves.
5. The supply valve must be sized for the maximum anticipated
steam load.
6. Do not drip steam mains into coil sections. Drip them on the
pressure side of the control valve and trap them into the return
main beyond the trap for the coil.
7. Do not use a single trap for two or more coils installed in
series. Where two or more coils are installed in a single bank,
in parallel, the use of a single trap is permissible, but only if
the load on each coil is equal. Where loads in the same coil
bank vary, best practice is to use a separate trap for each coil.
Variation in load on different coils in the same bank may be
caused by several factors. Two of the most common are
uneven airflow distribution across the coil and stratification
of inlet air across the coil.
8. Do not try to lift condensate above the coil return into an
overhead main, or drain into a main under pressure with a
modulating or on/off steam control valves. A pump and
receiver should be installed between the coil condensate traps
and overhead mains and return mains under pressure.
9. Use a strainer (3/32 in. mesh) on the steam supply side, as
shown in the piping diagrams, to avoid collection of scale or
other foreign matter in the inner tube distributing orifices.
NOTE: IDT coils must be installed with the tubes draining toward
the header end of the coil. The IDT steam coils are pitched toward
the header end as installed in the unit.
10. Ensure the AHU (air-handling unit) is installed level to main-
tain the inherent slope. Also ensure the unit is installed high
enough to allow the piping to be installed correctly, especially
the traps which require long drip legs.
11. Do not fail to provide all coils with the proper air vents to
eliminate non-condensable gases.
12. Do not support steam piping from the coil units. Both mains
and coil sections should be supported separately.
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Productinformatie
| Merk | Carrier |
| Model | 39S |
| Categorie | Niet gecategoriseerd |
| Taal | Nederlands |
| Grootte | 10967 MB |
