76
Direct-Fired Make-up Air •
MUA-SVX01A-EN
Trouble Shooting
–
using a screw driver, turn the inner adjustment screw for HI pressure
clockwise to increase or counterclockwise to decrease the gas pressure to
the burner.
6.
After high pressure has been checked, check low pressure regulation. Two
stage appliance operating sequences vary. Consult the valve manufacturers
instructions for the specific operating sequence and regulator adjustment
procedure for the valve in which the control is installed and for instructions
on how to prevent the control from moving to high stage while checking the
low pressure regulator setting.
7.
Check the low rate manifold pressure listed on the valve nameplate. Gas
control low rate outlet pressure should match this rating.
8.
With main burner operating, check the gas control flow rate as before (using
the meter clocking method or check pressure using a manometer connected
to the outlet pressure tap on the control).
9.
If necessary, adjust the low pressure regulator to match the appliance rating.
–
Remove the pressure regulator adjustment cap.
–
Using a screw driver, turn the inner adjustment screw to LO pressure
clockwise to increase, or counterclockwise to decrease the gas pressure to
the burner.
10. Once high and low pressure have been checked and adjusted, replace
pressure regulator adjustment cap. If the desired outlet pressure regulator or
flow rate cannot be achieved by adjusting the gas control, check the control
inlet pressure using a manometer at the inlet pressure tap of the control. Take
the necessary steps to provide proper gas pressure to the control.
Check Safety Shutdown Performance
Read steps 1 through 7 before starting, and compare the safety shutdown or
safety lockout tests recommended for the intermittent pilot (IP) ignition module.
Where different, use the procedure recommended for the module.
1.
Turn off gas supply.
2.
Set the thermostat or controller above room temperature to call for heat.
3.
Watch for ignition spark or for glow at hot surface ignitor either immediately
or following prepurge. See IP module specifications.
4.
Time the length of the spark operation. See IP module specifications.
5.
After the module locks out, open the manual gas knob and ensure no gas is
flowing to the pilot or main burner. With modules that continue to spark until
the pilot lights or the system shuts down manually, the pilot should light
when the manual gas control knob is opened.
6.
Set the thermostat below room temperature and wait one minute.
7.
Operate the system through one complete cycle to ensure all controls
function properly.
Gas Control Valve
