Installation, Operation & Maintenance Manual
IM-895
11
4. With the Fan On/Off switch still in the "Off" position, turn on the electrical supply to the unit.
5. Move the Fan On/Off switch to the "On" position (to activate the unit with heat disabled).
6. Check the blower for proper rotation per the airflow arrow on the blower.
7. Check the motor voltage. For three phase systems, check to make sure the voltage on all 3 legs vary less than 2%.
8. Check the motor Amp draw to be sure it does not exceed the motor nameplate FLA rating.
9. Measure the unit air volume being delivered and compare to the rated air volume on the unit serial plate. The most accurate
way to measure the air volume is by using a pitot traverse method downstream of the blower. Other methods can be used but
should be proven and accurate.
10. Recheck the gas supply pressure by installing a gas pressure gauge connected to the inlet gas pressure test port indicated on
the piping diagram included with the unit.
If the unit has an inlet gas pressure gauge, the pressure can be read directly from the gauge without needing to connect
a separate gauge. Refer to rating plate for proper gas supply pressure to unit. If inlet gas pressure exceeds the maximum
pressure specified on the rating plate, a gas pressure regulator needs to be added upstream of the factory furnished and piped
components.
Refer to the heater rating plate for determining the minimum gas supply pressure to obtain the full heating capacity for which
this heater is specified.
11. The unit includes Direct Spark Ignition (no pilot line), check the flame rod
flame sensor signal with the following steps:
a. Check that all manual reset safety devices have been reset to their
normal operating position.
b. Set the Burner On/Off switch to "On" and set the temperature controls
to call for heat.
d. The spark ignitor should begin to spark in approximately 10 seconds
and the burner flame should be established within 10 seconds.
12. Check the pressure differential across the burner profile per the following:
a. Remove the tubing plug from the burner gas pressure tap labeled
"BGPT" and connect an inclined manometer.
b. If the outdoor air temperature is below 60°F, fire the main burner to achieve a discharge air temperature of approximately
70°F. If the burner does not fire under these conditions, refer to the Troubleshooting Guidelines section of this manual for
additional guidance. If the outdoor temperature is 60°F or greater, do not fire the main burner.
c. Read the pressure differential reading on the burner pressure gauge or manometer. The actual installed pressure differential
reading must be 0.55" w.c. +/- 0.05" w.c. or 0.50" w.c. to 0.60" w.c.
d. If the differential pressure is out of range and cannot be achieved, contact the factory for additional guidance.
e. When the correct burner velocity pressure differential is verified, turn the unit off and open the main disconnect switch.
Remove the manometer and replace the tubing plugs in the burner gas pressure tap.
13. The high fire manifold (burner) pressure must be checked to ensure it matches the pressure shown on the unit serial plate.
Over-firing from high pressure can result in poor combustion and undesirable levels of combustion byproducts being
introduced to the heated space. The procedure is outlined in the following steps:
a. With the unit off, close the main gas manual hand valve. If not equipped with a burner gas pressure gauge, remove the
1/8" pipe plug test port at the burner and attach a water manometer or "U" tube that is at least 12" high. See piping diagram
furnished with the unit for pressure tap locations.
b. Start the unit and record the burner suction pressure present at the test port and record the negative number. Next, open
the gas valve and allow the burner to ignite (resetting the burner lockout if necessary). Observe the flame during the 10
second at low fire start to make sure it lights across the entire length of the burner and is stable with a clean blue flame.
c. Add the high fire pressure listed on the rating plate to the negative burner suction pressure recorded above. The resulting
sum is the actual measured gas pressure required for high fire in the next step.
d. Initiate a short (10-second) period of high fire. High fire can be achieved by removing wire 29 from terminal 4 on the
Maxitrol amplifier.
Check, Test & Start-Up Procedure
(cont.)
Direct Spark Ignition Components
SIDE VIEW
INTO AIRFLOW VIEW