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4. CONTROLS
WARNING: Installation, adjustment and service of
A
heater controls, including timing of various operating
functions, must be performed by a qualified installer,
service agency or the gas supplier. Failure to do so may
result in control damage, heater malfunction, property
damage, personal injury, or death.
WARNING: Turn off the power to the heater before
A
installation, adjustment or service of any heater controls.
Failure to do so may result in board damage, heater
malfunction, property damage, personal injury, or death.
CAUTION: This appliance has provisions to be
A
connected to more than one supply source. To reduce the
risk of electric shock, disconnect all such connections
before servicing.
CAUTION: Risk of electric shock: More than one
A
disconnect switch may be required to de-energize the
equipment before servicing.
4.1. Ignition Control Functions
When there is a call for heat, and all safeties are closed
and minimum flow rate detected, then the combustion air
blower starts to purge air from the combustion chamber.
After the pre-purge, the igniter is energized. The standard
ignition module will lock-out after failing to light 3 times
during a call for heat. To reset the lock-out, press and
release the RESET button located adjacent the user
interface. The control will automatically reset after 1 hour.
When in lock-out the control will run the blower through a
post-purge cycle.
The single-try ignition module (part of the CSD-1 option)
will attempt to light only one time before lock-out occurs.
To reset the lock-out, press and release the RESET button
located adjacent the user interface.
Turning off the power to the heater WILL NOT reset the
single-try ignition module.
NOTE: Ignition modules are common for all XTherm model
sizes. However, model-specific operating parameters are
defined by their respective ID cards.
4.2. High Limit - Manual Reset
This heater is equipped with a fixed-setting manual reset
high limit temperature device as standard. It may also
have an additional optional adjustable manual reset high
temperature device.
The optional manual reset high limit is located inside the
cabinet on the upper right corner post. See Figure 2.
STANDARD
(Fixed)
Figure 45. High Limit (Manual Reset)
The fixed-setting manual reset high limit is built into the
PIM, and utilizes a dual-element sensor located on the
outlet. See Figure 2.
H
240°F (116°C)
WH
200°F (93°C)
P
180°F (82°C)
To reset a high limit lock-out, press and release the RESET
button located adjacent the user interface.
4.3. High Limit - Auto
Reset (Optional)
This heater may be equipped with an optional adjustable
auto-reset high limit temperature device.
The optional adjustable auto reset high limit is located
inside the cabinet on the upper right corner post. See
Figure 2. Adjust the setting to approx. 20°F (11°C) above
desired outlet temperature.
4.4. Variable-Speed Injector Pump
Some XTherm models are equipped with dual variable-
speed injector pumps, like the one shown below. Figure
46 shows the DIP switch settings, setpoint (MIX Target)
and factory wiring.
Figure 46. Variable-Speed Injector Pump
OPTIONAL
(Adjustable)
39
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