35
Time Clock/Fireman’s Switch
To operate the heater with a time clock, connect the timer
The time clock should be of the dual switch type and set to
digital control board. Splice into the red wire jumper tagged
must be a dry contact and must not supply power to the
may damage the heater, and is not covered by warranty.
NOTE: When using a time clock, the heater will display
High Limits
The heater is equipped with two automatic high limits. Both
are located in the inlet/outlet header. Both are set to open
NOTE: An erratic high limit is often characteristic of
an internal heat exchanger problem, e.g. scale build-up,
page 41).
High Limit Removal
Shut off main electrical power switch to heater.
Remove front door.
Remove defective high limit and replace with a new
high limit.
Replace inspection panel.
Figure 38. High Limit
Flow Switch
Figure 39. Flow Switch
Blocked Vent Switch
This heater is equipped with a blocked vent pressure
switch to prevent the operation of the heater when the vent
is blocked.
Figure 40. Blocked Vent Switch
Adjusting Valve Manifold Pressure
Gas manifold pressure is measured at the pressure
tap between the gas valve and gas orifice (See
Figure 40).
To increase the manifold pressure and increase
the ratio of fuel to air turn the adjustment screw
Figure 33).
adjustment screw counterclockwise. Increasing
manifold pressure will increase the CO percentage
in the flue gases.
To decrease the manifold pressure and decrease the
ratio of fuel to air turn the adjustment screw clockwise
Figure 41). Decreasing manifold
pressure will reduce the CO percentage in the flue
gases.
NOTE: Manifold pressure will decrease when the intake
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