FloAire INDIRECT FIRED BENT TUBE MODULE - Manual (Page 17)

17
Maxitrol Modulating Valve
The gas pressure should be set at 3.5 in w.c. for natural gas and 10 in w.c. for propane to obtain
maximum efficiency. If the gas pressure needs to be adjusted remove the pressure regulator
adjustment cap and screw on the ON/OFF valve and using a screwdriver, turn the inner
adjustment screw clockwise to increase the gas pressure. Once proper gas pressure has been
set for these non-modulating stages leave them lit and move on to step # 3.
3. Create a high fire call for heat on the modulating gas valve(s). This should be done with the
blower on and all gas controls on as described in step # 2. High fire can is achieved using the
heat controller FVFAB by
going to “menu”, “test mode”
and then “high fire”. An
alternative
method is to
disconnect the leads going
from
the discharge
temperature sensor to the
thermostat. Next, remove the
cover
on the Maxitrol
Modulating Valve and press
button #1 until the LED lights
solid red. Release. The valve
is now in high fire setting
mode. Buttons #1 and #2 are
used to set desired high fire
setting. Press or hold button
#1 to increase gas flow. Each
button press equates to the
minimum available step size
and will decrease slowly. Holding the button down auto steps and eliminates the need to
continuously press the button. Use this feature to rapidly decrease the flow. Manifold pressure
can be read off of the 0-10” w.c. gas pressure gauge located directly on the gas manifold. For
natural gas systems, the high fire manifold pressure should be set at 3.5 in. w.c. For propane
gas, the high fire manifold pressure should be set to 10 in. w.c. To save the high fire setting,
simultaneously hold buttons #1 and #2 until the LED turns off. If 3.5” w.c. gas pressure cannot be
achieved at high fire by adjusting the modulating gas valve and it has been verified that the inlet
gas pressure is within the acceptable range of 7-14” w.c., adjust the regulator of the ON/OFF gas
valve located upstream of the modulating gas valve. To do this remove the pressure regulator
adjustment cap and screw on the ON/OFF valve and using a screwdriver, turn the inner
adjustment screw clockwise to increase the gas pressure at the inlet of the modulating gas valve.
4. Using buttons #1 and #2, adjust the high fire manifold pressure to 3.5 in. w.c. for natural gas and
10 in. w.c. for propane gas. If button #1 is at the end of its adjustment and more pressure is
needed, then adjust the main gas pressure regulator spring (on the On/Off valve) to achieve the
proper manifold pressure. Turning the regulator screw clockwise will increase pressure and
counter-clockwise will decrease pressure.
5. Save the high fire setting by simultaneously holding down buttons #1 and #2 until the LED turns
off. Press any button on the FVFAB to exit high fire mode.
6. The low fire manifold pressure must now be set. Low fire mode from the FVFAB is achieved by
going to “menu”, “test mode” and then “low fire”. An alternative method is to connect together the
two leads coming from the discharge thermostat instead of them each connecting to the
discharge air sensor. This ensures a reading of 0 Ohms to the thermostat. Next, press and hold
button #2 on the Maxitrol modulating valve until the LED light blinks red. Release. The valve is
now in low fire setting mode. Buttons #1 and #2 are used to set desired low fire setting at this
point. Press or hold button #2 to decrease gas flow. Each button press equates to the minimum
available step size and will decrease flow slowly. Holding the button auto steps and eliminates
the need to continuously press the button. Use this feature to rapidly decrease the flow. Press or
hold button #1 to increase gas flow. Each button press equates to the minimum available step
size and will increase slowly. Holding the button down auto steps and eliminates the need to
continuously press the button. Use this feature to rapidly increase the flow.