Cambridge Air Solutions.
34
M-Series Technical Manual
hr), close the manual burner shut-off
valve and wait 30 seconds to read the
manometer. If the reading is greater than
0
inch
WC, replace the gas valve and retest.
If the reading is 0 inch WC, remove the
manometer and reinstall the pipe plug.
b.2. On heaters with separate redundant
valves, close the manual burner shut-
off valve, hold the momentary leak test
switch in the closed position, and wait
30 seconds to read the manometer. If the
reading is greater than 0
inch
WC, refer
to the Maintenance Instruction Section
for information on Gas Valve Cleaning
(page 62) for cleaning the safety shut-off
valve (SSV) which is closest to the burner
and retest. If the reading is 0
inch
WC,
remove the manometer and reinstall the
pipe plug.
c. To check the gas tightness of the shut-
off valve (SOV) in the gas train which is
farthest from the burner on heaters with
separate redundant valves, connect the
manometer to the leak test port between
the valves and verify that the manometer
is properly zeroed. Wait 30 seconds to
read the manometer. If the reading is
greater than 0
inch
WC, refer to the
Maintenance Instruction Section (page 62)
for information on Gas Valve Cleaning
for the shut-off valve (SOV) gas valve
and retest. If the reading is 0
inch
WC,
remove the manometer and reinstall the
pipe plug.
9. GAS TRAIN LEAK CHECK
a. Turn the blower and burner service
switches to the
“
LOCAL
”
position.
b. With the burner operating, spray the
complete gas train with leak detector
solution, checking all pipe connections
and plugs.
c. Turn the blower and burner service
switches to the
“
OFF
”
position.
WARNING:
Do not use flame to leak check piping.
WARNING:
Any gas leak detected must be repaired before the
make-up air heater is placed into service.
10. MINIMUM FIRE SETTING
IMPORTANT
All access doors must be closed during this procedure.
a.1. For units with an A1014 or an A1044
amplifier: Reinstall #3 wire on the
amplifier that was removed in Step 7.b.1
(See page 32).
a.2. For units with a signal conditioner
(SC25S): Remove the 1100 Ohm resistor
and re-install the push ons for T1 & T2 and
terminals #5 & #6 that were removed in
Step 7.b.2. (See page 32).
b. Connect a meter set to read DC
microamps (
m
A) in order to verify the
minimum fire flame signal during the
adjustment process. Connect the meter by
removing the red wire from terminal FP
of the flame safe
g
uard relay (FSR) and
attaching the positive lead of the meter to
terminal FP and the negative lead to the
red wire.
c. Turn the blower and burner switches to
the “LOCAL” position.
d.1. For units with an A1014 or an A1044
amplifier: After the burner has
ignited, remove the #8 wire
from the amplifier to drive the modulating
valve to minimum fire.
d.2. For units with a signal conditioner
(SC25S): After the burner has ignited,
remove the push on for terminal #3 to
drive the modulating valve to minimum
fire.
e. Look through the burner viewport in
the front of the heater to verify that
the burner flame is a very small ribbon
(approximately 1-1/2" to 2
"
long
)
that is
evenly spread across the burner (without
gaps).
