Installation and Maintenance Manual

Start-Up
40 GTND-SVX01B-EN
3. Turn on the electrical power. The unit heater should
now be under the control of the thermostat. Set the
thermostat to its highest setting; the power venter
motor should start and burner ignition occur. Turn the
thermostat to its lowest setting; the power venter
motor shuts off and the burner(s) should extinguish.
Reset the thermostat to the desired operational setting.
Note: F
or more information, refer to “Gas Input Rate,”
p. 40 and “Gas Pressure Adjustments,” p. 40.
Shut-Down
1. Turn the valve selector knob to the OFF position.
2. Turn off the electricity.
3. To relight, follow the instructions in “Start-Up (also
refer to lighting instruction plate equipped on the
unit),” p. 39 (preceding section).
Refer to the figures for par
ts/identification:
• All unit sizes: Refer to Figure 2, p. 8.
• Unit sizes 30–120: Also refer to Figure 3, p. 9 through
Figure 6, p. 10 and Figure 40, p. 40.
• Unit sizes 150–400: Also refer to Figure 7, p. 10 through
Figure 12, p. 11 and Figure 41, p. 40.
Primary Air Adjustment
Primary air adjustment is made at the factory. No field
adjustments are necessary.
Gas Input Rate
Check the gas input rate as follows (refer to “General
Safety Information,” p. 7 for metric conversions):
1. Turn off all gas appliances that utilize gas the same
meter as the unit heater.
2. Turn gas on to the unit heater.
3. Using the gas meter, clock the time that
it takes to burn
one cubic foot of gas (Heating Value).
4. Insert the time, in seconds, into the
formula below:
Example: If the heating value = 1000 BTU/ft
3
and the time/
ft
3
= 48 s/ft
3
then
Input Rate = 75,000 BTU/hr
(Refer to “General Safety Information,” p. 7 for metric
conversions.)
Note: If the computation exceeds, or is less than 95
percent of the gas Btu/h input rating, adjust the gas
pressure:
• Unit sizes 30–120: Refer to Table 1, p. 12.
• Unit sizes 150–400: Refer to Table 2, p. 14.
Gas Pressure Adjustments
Adjust the gas pressure as follows:
1. NATURAL GAS: Best results are obtained when the
heater is operating at its full input rating with the
manifold pressure of 3.5 inches wc (0.9 kPa).
Adjustment of the pressure regulator is not normally
necessary since it is preset at the factory.
However, field adjustment may be made as follows:
a. Attach manometer at pressure tap plug:
• Unit sizes 30–120: The pressure tap plug is below
the control outlet.
• Unit sizes 150–400: the pressure tap plug is
adjacent to the control outlet.
Figure 40. Unit sizes 30–120: Burner parts/identification
Figure 41. Unit sizes 150–400: Burner parts/
identification
NOTICE:
Overfiring!
Never overfire the unit heater, as this could cause
unsatisfactory operation, or shorten the life of the
heater.
Input Rate =
Heating Value (Btu/ft
3
) (3600 s/hr)
Time (s/ft
3
)
Input Rate =
(1000 BTU/ft
3
) (3600 s/hr)
48 s/ft
3