Service manual

35
Air Flow Setting
The fan inlet air shutter has been preset at the
factory. The following description is for the
benefit of the start-up technician should minor
adjustment be required.
Optimum results are obtained when the
appliance is operated with air box pressure as
set in Table 12. If adjustment is necessary the
following steps must be followed: Remove the
lower front jacket panel; connect a manometer
to the air pressure tap provided on the
combustion chamber door; with the fan
operating the air pressure should be set per
Table 12 by adjusting the air inlet shutter on the
fan inlet; To adjust the air shutter, first undo the
securing nut and rotate the bolt so the shutter
will open or close as required
Table 12 – Combustion Values
Natura
l Gas
Propane
CO
2
CO CO
2
CO
Non-
Condensing
Max.
Fire
7.5% -
8.5%
< 50
PPM
9.0% -
10.0%
< 50
PPM
Min.
Fire
7.0% -
7.5%
< 50
PPM
8.5% -
9.0%
< 50
PPM
Condensing
Max.
Fire
8.5% -
9.0%
< 50
PPM
10.0% -
10.5%
< 50
PPM
Min.
Fire
7.5% -
8.0%
< 50
PPM
9.0% -
9.5%
< 50
PPM
Once satisfied tighten the nut on the fan’s
shutter bolt making sure it is secured.
Pressure Switch Settings
The air flow proving switches have been preset
at the factory as per Table 12. The following
description is for the benefit of the start-up
technician should minor adjustment be required.
One pressure switch is provided per burner. If
adjustment is necessary the following steps
must be followed: Remove the lower front jacket
panel; insert allen key into the switch located on
the combustion chamber door; with the fan
running the switch should be set per Table 11 by
rotating the allen key counter-clockwise to make
contact.
Ignition System Safety Shut-Off Device
After initial fill while the main burner is firing,
shut off gas to the pilot and clock the time taken
for the main gas valve to shut down. If the safety
control is functioning properly, power to the gas
valve will be shut off within 4 seconds of the pilot
gas being shut off. If shut down takes longer,
ignition control or gas valve may be defective.
If shutdown does not occur it is possible that the
main flow is generating a signal at the pilot in
which case the pilot shall not recycle with the
pilot gas off.
Appliances Start Up
With the appliance off, open makeup water valve
and allow system to fill slowly. With all air vents
open, run system circulating pump for a
minimum of 30 minutes with the appliance off.
Open all strainers in the circulating system and
check for debris. Check liquid level in expansion
tank. With system full of water at 15 PSIG cold,
the level of water in the expansion tank should
not exceed ¼ of the total volume with the
balance filled with air. Start up appliance
following instructions provided. Operate entire
system including pumps and radiation for at
least 1 hour. Check water level in expansion
tank. If level exceeds ½ of tank volume, air is
still trapped in system. Shut down appliance and
continue to run pumps. Within 3 days of start up,
recheck all air vents and expansion tank as
described above.
10.2 MODULATION SEQUENCE
The Modulating MicoFlame Grande is designed
with intermittent pilots on each burner. Before
the appliance can light off, all pilots must be lit.
Pre-purge
BTC 1 Staging control activates the pre-purge
cycle for 20 seconds before trial for ignition.
Ignition Trial
On proof of air flow, the air proving switch closes
and energizes the ignition module. The module
first initiates a self check and then starts the pilot
ignition sequence. The modulating sequence
begins with the modulating fan ramping down to
ignition speed. The safety shutoff valve opens,
which allows gas to flow to the pilot burner. At
the same time, the electronic spark generator in
the module produces 10,000 Volt spark pulse
output. The voltage generates a spark at the
igniter that ignites the pilot. If the pilot does not
light, or the pilot flame current is not at least, on
average, 1.5 µA and steady, the module will not
energize the combination valve and the main
burner will not light. The ignition module
provides 100% gas shutoff, followed by retry for
ignition. If required (e.g. CSD-1) a module with
lockout feature can be provided.