70
Figure 35: Burner Flame
throttle screw counter-clockwise in 1/4 turn
increments and checking the O
2
(or CO
2
) after
each adjustment. If boiler is equipped with 2 gas
valves, throttle screw adjustments must be done
to both gas valves equally and simultaneously.
Refer to Figure 36 for location of throttle screw.
Verify CO is less than 100 ppm.
d. Lock boiler in low fire and allow boiler to
operate for approximately 5 minutes before
taking combustion readings. Press “Low” to
lock boiler in low fire.
WARNING
Asphyxiation Hazard. Offset screw is adjusted
at the factory to the specification. DO NOT
touch the offset screw if measured low fire O
2
(or
CO
2
) is within limits specified in Table 21 or 22.
e. If low fire O
2
is too low (CO
2
is too high),
increase O
2
(decrease CO
2
) by turning offset
screw counterclockwise in less than 1/8 turn
increments and checking the O
2
(or CO
2
) after
each adjustment. If boiler is equipped with 2 gas
valves, offset screw adjustments must be done
to both gas valves equally and simultaneously.
Refer to Figure 36 for location of offset screw.
Verify CO is less than 100 ppm.
f. If low fire O
2
is too high (CO
2
is too low),
decrease O
2
(increase CO
2
) by turning offset
screw clockwise in less than 1/8 turn increments
and checking the O
2
(or CO
2
) after each
adjustment. If boiler is equipped with 2 gas
valves, offset screw adjustments must be done
to both gas valves equally and simultaneously.
IX. System Start-up
(continued)
a. Lock boiler in high fire and allow boiler to
operate for approximately 5 minutes before
taking combustion readings. To lock boiler in
high fire, from the home screen, press “Adjust”,
“Adjust”, “Login”, “000”. Enter the password
“086” and press return arrow to close the keypad.
Press “Save”, “Adjust”, “High” to lock boiler in
high fire.
WARNING
The offset screw has been factory set using
precision instruments and must never be
adjusted in the field unnecessarily. The gas
valve outlet pressure is the same for both natural
gas and propane. Make sure that all adjustments
are made with the throttle, not the offset screw
(see Figure 36). Attempting to adjust the offset
screw unnecessary will result in damage to the
gas valve and may cause property damage,
personal injury or loss of life.
b. If high fire O
2
is too low (CO
2
is too high),
increase O
2
(decrease CO
2
) by turning the throttle
screw clockwise in 1/4 turn increments and
checking the O
2
(or CO
2
) after each adjustment.
If boiler is equipped with 2 gas valves, throttle
screw adjustments must be done to both gas
valves equally and simultaneously. Refer to
Figure 36 for location of throttle screw. Verify
CO is less than 100 ppm.
c. If high fire O
2
is too high (CO
2
is too low),
decrease O
2
(increase CO
2
) by turning the
Figure 36: Gas Valve Detail
Table 22: Typical Combustion Settings,
LP Gas
Boiler
Model
High Fire
Low Fire
CO,
PPM
% CO
2
% O
2
% CO
2
% O
2
APX425 11.4 - 9.5 3.5 - 6.5 11.4 - 9.1 3.5 - 7.0
Less than
100 PPM
APX525 10.8 - 9.1 4.5 - 7.0 10.8 - 9.1 4.5 - 7.0
APX625 9.6 - 9.2
6.3 - 7.0
9.6 - 8.0 6.5 - 8.8
APX725 9.6 - 9.2
6.3 - 7.0
9.6 - 8.0 6.5 - 8.8
APX825 10.8 - 9.1 4.5 - 7.0 10.8 - 9.1 4.5 - 7.0
Summary of Contents for APEX
Page 57: ...57 VIII Electrical continued Figure 26 Ladder Diagram ...
Page 58: ...58 VIII Electrical continued ...
Page 59: ...59 Figure 27 Wiring Connections Diagram VIII Electrical continued ...
Page 105: ...105 ...
Page 109: ...109 XIII Repair Parts continued APX625 APX725 and APX825 APX825 shown ...
Page 112: ...112 XIII Repair Parts continued APX425 and APX525 ...
Page 114: ...114 XIII Repair Parts continued APX625 APX725 and APX825 ...
Page 122: ...122 ...
Page 123: ...123 ...
