Troubleshooting guide

PV500-17 07/13 Section 17
10
MAXIM
AXIAL FLOW GAS BURNER START-UP (continued)
PRESSURE PLATE
Set up and Tolerances
Figure 17-3
13. Connect a test meter to the control for
reading the flame response signal.
IMPORTANT
Some controls read the flame signal in
micro amps and some in volts DC. The TFM
or MEC120 series control has two terminals
marked for reading volts DC. The S89
control uses a micro amp signal for
measuring flame strength. For this control, a
meter must be hooked in series with the
flame rod wire. Disconnect the leadwire at
the S89 sensor terminal. Connect the
positive lead of the meter to the quick-
connect sensor terminal on the S89 and the
negative lead to the free end of the sensor
leadwire.
14. Be sure the tank is filled with water. Once
the burner is reassembled, two devices will
be needed to read gas pressures,
preferably U-tube manometers. Connect
one to read the inlet pressure of the burner.
This is the pressure measured before all
components in the gas train. The
manometer must stay connected
throughout the testing as the inlet pressure
must be monitored during the firing of the
burner.
Record static pressure; it must not exceed
14" W.C. Pressures above this could cause
damage to the diaphragm in the gas valve or
pressure regulator.
15. Burners with pilot; inputs over 400,000
Btu/h (See wiring diagram.)
16. Connect a manometer to the manifold test
port at the shutoff valve closest to the
burner. Turn off the main gas shutoff valve.
Set the air shutter as shown on the tag
attached to gas train. This may not be the
exact setting you end up with, but it is a
good starting point. Turn the unit on using
the rocker switch on the side of the control
enclosure assembly. If the operating control
switches are closed, the burner blower
should come on and pre-purge begin.
If nothing happens, check the control to be
sure it is not in the tripped position and
reset it by pushing the flame safeguard
reset button. The burner should pre-purge
for no longer than thirty seconds.