80
Direct-Fired Make-up Air •
MUA-SVX01A-EN
Trouble Shooting
5. If pilot does not light after
prepurge has timed out and
there is no voltage at flame
safeguard relay output
terminals.
Flame safeguard relay run/
test switch in test position or
functioning problem.
a. Place in run position (see
technical cut sheet on flame
safeguard relay).
6. If there is no heat with
pilot ok and voltage is
present at flame safeguard
relay output terminals.
Manual gas shut-off valve
closed.
a. Turn HEAT-OFF-ON switch to
the OFF position. Slowly open
all manual gas shut-off valves
before restarting.
No gas on outlet side of
regulators with inlet pressure
ok.
a. Clear obstruction in vent
orifice/line or replace if
defective.
No gas on outlet side of valve
or actuator with inlet
pressure ok.
a. Turn HEAT-OFF-ON switch to
ON position. After 10-seconds
of prepurge, pilot will light.
Then after 5 to 10-seconds
main valve light will come on.
Check to see if all gas valves
have opened. If not, check
voltage at gas valve. If voltage
is found to be correct, replace
gas valve or actuator (see
Maxitrol trouble shooting guide
for modulating valve).
Main flame rod or scanner
not sensing main burner.
a. Check burner for low fire
adjustment.
b. UV Sensor - clean lens and
sight tube. Check wiring.
c. Flame Rod - assure flame rod
is in main flame. Check wiring
and flame rod.
Flame safeguard relay run/
test switch in test position or
functioning problem.
7. If no heat with pilot ok,
and no voltage is present at
flame safeguard relay output
terminals.
a. Place in run position (see
technical cut sheet on flame
safeguard relay).
For Maxitrol system.
8. Burner will not respond to
temperature.
For RTC system.
a. Refer to trouble shooting
guide for Maxitrol MDT or MRT
controls.
Defective photohelic switch
a. Refer to trouble shooting
guide for RTC MDT control.
9. 75/25 or 505/50 return
air/outside air or discharge
air/profile damper operation
not functioning properly (see
sequence of operation for
damper control).
Photohelic or null switch
wired incorrectly.
a. Check and/or replace.
Table 16. Trouble shooting guide for systems with pilot (continued)
Symptom
Probable Cause
Solution
