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2. Verify that the steam trap on the valve/trap assembly of
the humidifier is working properly — condensate dis-
charge line should be hot.
3. With air flowing in the duct or air handler, create a hu-
midification demand by increasing the humidity control
set point until it exceeds the actual humidity reading.
4. The valve on the humidifier should begin to open and
steam should enter the humidifier manifolds.
5. Initially most of the steam will condense as it heats the
manifolds. Ensure that the P-traps on the manifolds are
clear and running to drain without leaking steam.
NOTE: On first start-up, some steam may leak from the
P-traps on the manifolds if they have not been primed
(filled with water).
6. Steam should begin exiting the humidifier manifolds.
7. Return the humidity control set point to the desired level.
COILS
Water Coil
Typical coil vents, drains, and lifting points are shown in Fig. 97.
Open the vent plug, partially turn on the water supply until air is
exhausted, and replace the vent plug. Fully turn on the water
supply.
Direct Expansion Coil
Charge with refrigerant. Refer to Condensing Unit instructions.
Refrigerant operating charge is shown in Table 18 on page 64.
Steam Coil
1. Generate steam in the steam main and open the supply
(gate) valve to the coil.
2. Thoroughly preheat the coil with steam before starting
fans, especially when inlet air temperature is below
freezing. If water hammer occurs, turn off fans until con-
densate trapped in coils is reduced by heat and steam
pressure.
3. Ensure continuous-vent petcock is open; also check oper-
ation of gate valves, control valve, and check valves.
4. After operating coil for 50 hours, check strainer and re-
move any foreign matter. Check traps and drip lines for
correct condensate removal. Where necessary, increase
the pitch of lines to increase condensate drainage. (Re-
check operation after 50 hours and repeat if necessary.)
INTEGRAL FACE AND BYPASS COIL START-UP
Ensure that the damper operator allows the dampers to fully close
the face and reverses to fully close the bypass. Set the thermostat
so that the face opens and bypass closes when heat is required.
On start-up, the steam or hot water supply will be fully expanded
prior to start of airflow. Allow time for all air to be purged from
the system and for the heating surface to fully warm up in order to
avoid heating lag.
Preheating a cold system will avoid excessive steam condensate
loading at the start of operation of a steam heating system. It also
protects steam and hot water units against freezing up when sub-
ject to sub-freezing air temperatures. After preheating, fully open
the dampers for full-face exposure (bypass closed). Start airflow.
Set thermostat for desired air temperature.
ELECTRIC HEATERS
1. Check tightness of all electrical connections.
2. Remove heater circuit fuses.
3. Turn on power to activate transformer.
4. Start up base unit fans. Check airflow and switches. Refer
to base unit instructions as required.
5. Set thermostats so that heater contactors will operate.
6. Shut off unit power.
7. Reinstall fuses.
8. Turn on unit power and heater power.
GAS-FIRED FURNACES (DUCT AND RACK SYSTEM)
Refer to the wiring diagram and sequence of operation documents
included in the furnace section of the unit, or contact your Carrier
service representative for assistance with this information, before
attempting to place the single unit heater or rack system into
service.
The use and storage of gasoline or other flammable vapors and
liquids in open containers in the vicinity of this appliance is
hazardous and may result in fire or explosion.
Also, note the following points:
• The duct furnace(s) or rack system furnaces do not have a
pilot. They are equipped with a direct spark ignition device
that automatically lights the gas burner. Do not try to light
burners by hand.
• Before operating, leak test all gas piping up to heater gas
valve. See the section Gas Supply, Piping, and Connections
on page 191 (duct furnaces) or page 196 (rack system fur-
naces). Smell around the unit area for gas. Do not attempt to
place heater in operation until source of gas leak is identi-
fied and corrected.
• Do not attempt to operate unit if there is any indication that
any part or control has been underwater. Any control or
component that has been under water must be replaced prior
to attempting to start the unit.
• Use only hand force to push and turn the gas control knob to
the "ON" position. Never use tools. If knob does not operate
by hand, replace the gas valve before starting the unit.
If the gas control knob does not operate by hand, replace it
before starting the unit. Forcing or attempting to repair the gas
valve may result in fire or explosion.
Start-Up (Duct Furnace)
Follow these steps to start the gas-fired duct furnace:
1. Turn thermostat or temperature controller to its lowest set-
ting.
2. Turn off gas supply at the manual shut-off valve.
3. Turn off power to the unit at the disconnect switch.
4. Remove access panel or open door to unit vestibule housing
the gas heater.
5. Move gas control knob to "OFF" position.
6. Install a tapped fitting for attachment to a manometer, or oth-
er gage suitable for 14.0 in. wg in the inlet pressure tap, and
for 10.0 in. wg in the manifold pressure tap.
7. Wait 5 minutes for any gas to clear out. If you smell gas, see
Step 2 and correct leak. If there is no odor or leaks have been
corrected, go to the next step.
8. Turn gas control knob to "ON" position.
9. Open all manual gas valves.
10. Turn power on at disconnect switch.
11. Set thermostat or controller to its highest position to initiate
call for heat and maintain operation of unit.
The draft inducer will run for a 15 to 30-second pre-purge period.
At the end of the pre-purge period, the direct spark will be ener-
gized and the gas valve will open. The burners ignite.
Failure to Ignite (Duct Furnace)
On the initial start-up, or after the unit has been off for long peri-
ods of time, the first ignition trial may be unsuccessful due to the
209
WARNING
WARNING
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