Greenheck TSU Direct Gas Manual (456857) - Manual (Page 5)

5
SYSTEM STARTUP (cont.)
c. Adjust High Fire
Monitor the temperature difference between the inlet air and blower discharge temperature. Adjust the
main regulator by turning the adjustment screw inside the main regulator until the required temperature
rise is equal to the actual temperature rise. On units over 1,000,000 BTU's, the regulator is built into the
modulating valve.
d. Replace Wire
Reattach wire to proper terminal.
NOTE: This test procedure can be done in the summer, however, there will be hot air being blown into the
building and the high limit may trip out, requiring manual resetting.
5. Low Fire
For safe operation, the burner should have a flame across the entire burner at all times. This is factory set but
should be field inspected.
To check this, adjust the discharge temperature air to its lowest setting and view the flame. This should be
done when the outside air temperature is above the lowest discharge temperature setting. At all times there
should be a small flame present across the entire length of the burner.
If adjustment is required, refer to the Maxitrol manual provided with the unit.
6. Set Unit’s Discharge Temperature
Maxitrol Series 14 Systems
Set the temperature selector to the desired discharge temperature. (Maximum of 75º F on Canadian Units.)
Maxitrol Series 44 Systems
For Maxitrol Series 44 units the selectrastat T244 adjusts the discharge temperature according to the
building requirements. The discharge setting temperatures on the A1044E amplifier should be set.
Greenheck recommends the minimum be set to 50º F and the maximum be set at 100º F.
7. Flame Signal Check
To ensure trouble free operation, the flame rod signal to the flame safeguard should be checked. Readings
should be recorded in the following flame conditions: Pilot only, low fire, mid fire and high fire. The readings
should be steady and be at or above the recommended minimum reading shown below. If problems do exist
with this, see the Trouble Shooting section of this manual for more information.
To measure the flame signal:
For RM7895 Flame Safeguards
A standard DC volt meter can be used and connected at the flame amplifier test jacks + and - (com) on
the outside of the flame safeguard. The keyboard display module Honeywell #S7800A1001 (not provided)
can also be used to measure the flame signal. The signal will be in DC volts and should be above or at
1.25v and stable for all flame conditions.
8. Optional High/Low Gas Pressure Switch
These switches denergize the heater if the gas pressures are above or below the limits. Both switches are
manual resetting.
Typical settings are:
Low pressure at 2 inches wg
High pressure at 8 inches wg for natural gas and 4 inches wg for L.P. gas.