LAARS EDN Series - Installation, Operation and Maintenance Instructions - Manual (Page 35)

Endurance Page 35
to go through a normal cycle. If during this cycle
there is no flue odor, repair the leaky joints in the
flue pipe.
f. Safety limit trip: The safety limit on the
Endurance is interlocked with the boiler control.
If this limit detects outlet water temperature
greater than 230°F (110°C), or if there is a
component failure, the limit will open the
boiler circuit and the boiler control will
indicate LO on the display. The safety limit will
automatically reset when the water temperature
drops. If the temperature has exceeded 230°F
(110°C), determine the cause of the high water
temperature and correct. If the switch is tripped
when the water has not reached 230°F (110°C),
replace the switch.
SECTION 10.
Air Orifice and Gas
Valve Adjustment
If poor combustion is suspected because of a
strong exhaust smell, pulsation in the exhaust, or
nuisance flame failure lockouts (shown as “LO” on
LED), the air orifice may need to be adjusted.
Note: Direct vent installations may experience
poor combustion that results from cross contamination
of the combustion air source. Check for cross
contamination before attempting offset pressure
adjustment (see Section 9.2.3 step 5).
To adjust the air orifice, remove the door panel,
and remove the plug in the flue stack. Perform a CO
2
analysis while the boiler is running at the maximum
firing rate. (Pressing the enter button and the up arrow
on the boiler control, and holding them for 2 seconds,
places the Endurance in high fire for 5 minutes).
Natural Gas:
• If CO
2
is greater than 9.6, open the holes on
the adjustable inlet. Adjust the cover until
CO
2
is within the range listed in table 5.
• If CO
2
is less than 9.0, close off the
adjustable inlet. Adjust the cover until CO
2
is within the range listed in table 5.
LP Gas:
• If CO
2
is greater than 10.1, open the holes
on the adjustable inlet. Adjust the cover
until CO
2
is within the range listed in
table 5.
• If CO
2
is less than 9.7, close off the
adjustable inlet. Adjust the cover until CO
2
is within the range listed in table 5.
Reinstall the flue stack plug when finished
testing.
If CO
2
is still out of range, adjust the gas valve
calibration. (Always adjust the air orifice first.)
To adjust the gas valve calibration, see figure
35 for the location of the offset pressure port and the
offset adjustment. When adjusting the offset pressure,
the CO
2
will reduce as the offset pressure is adjusted
more negative. Adjust the offset pressure to achieve
the values shown in Table 5. Note that during the pre-
purge cycle, the gauge will indicate several inches w.c.
negative pressure.
Always check the CO
2
after making adjustment
to the gas valve.
IMPORTANT NOTE: FINAL ADJUSTMENT OF THE
OFFSET PRESSURE MUST ALWAYS RESULT IN A
NEGATIVE PRESSURE UPON COMPLETION.
Natural Gas LP Gas
CO
2
9.0 to 9.6 % 9.7 to 10.1 %
O
2
4.5 to 5.0% 4.5 to 5.0%
Offset -0.01 to -0.10 in. w.c. -0.01 to -0.10 in. w.c.
Table 5. Combustion Parameters.
SECTION 11.
Symptom Evaluations
11.1 Delayed ignition
Possible Causes
a. High lockup pressure (LP boilers) - occurs on
start-up.
b. Gas valve regulation problem - occurs on start-
up.
c. Incorrect gas orifice (Natural gas orifice in an LP
boiler) - occurs on start up
d. Defective burner - occurs on startup or at burner
shutdown.
High lock up pressure is the most common cause
of delayed ignitions on LP fueled boilers. It may result
from an improper second stage regulator selection or
from a faulty regulator.
Lock up can be detected by measuring the gas
supply pressure to the boiler at the inlet pressure tap
on the gas valve. The gas supply to the boiler must be
shut off before making this connection. Use a water
manometer or pressure gauge with a scale reading of
at least 25 in. w. c. or 15 oz/in 2 . Loosen the screw in
the gas valve pressure port one full turn and install a
hose from the pressure gauge over the pressure port.
Turn on the gas supply. The ENDURANCE boiler is
designed to operate with supply pressures of 4-13 in.
w. c. (2.3 - 7.5 oz/ in²). If the supply pressure exceeds
13 in. w. c. (7.5 oz/ in²) with the boiler not operating
it is possible that this may be the cause of delayed
ignitions and the pressure must be reset to ~ 9 in. w.
c. (5.2 oz/ in2). Restart the boiler and then switch it
off again. Lock up pressures must be measured when
the boiler is not operating and preferably immediately
after boiler shutdown. If the gas pressure again
exceeds the allowable values, correct the lock up
problem.