Cleaver-Brooks CBH 40 - C. PILOT FLAME, BUT NO MAIN FLAME; E. SHUTDOWN OCCURS DURING FIRING

Chapter 6---Trouble Shooting
c)
Insufficient or no voltage to gas pilot sole-
noid valve. Check power at relay terminal 5
3.
Low fire switch open
a) Damper motor not closed, slipped cam,
defective switch
b) Damper jammed or linkage binding
4. Check interlocks and circuit to relay terminal
12
5. Timer switch (CB20 or CB40) in TEST position
and timer stopped in "pre-purge"
C. PilOT FlAME, BUT NO
MAIN FlAME
1. Insufficient pilot flame
2. Gas fired unit:
a) Manual gas cock closed
b) Main gas valve inoperative
c) Low or high gas pressure (reset switch if
necessary)
3. Oil fired unit:
a) Oil supply cut-off by obstruction, closed
valve, or loss of suction
b) Pump inoperative; belt broken or slipping
c) No fuel
d) Inoperative solenoid valve
e) Check oil nozzles and lines
4. Inoperative programmer
a) If relay 2K does not pull in when pilot
flame lights, check flame detector, contacts,
amplifier
b) Flame detector defective, sight tube ob-
structed or detector lens dirty
c) If relay 2K pulls in but fuel valve isn't
energized, check for voltage at terminal 7.
If no voltage check contacts. (See bulletin)
D. BURNER STAYS IN lOW FIRE
l. Pressure or temperature above high-low fire
control setting
2. Damper positioning switch in wrong position
3. Inoperative damper motor (See Section F)
4. Defective high-low fire control
5. Binding or loose linkage, cams, setscrews, etc.
6. Check appropriate relay contacts
6-2
E. SHUTDOWN OCCURS DURING
FIRING
1. Loss or stoppage of fuel supply
2. Defective fuel valve; loose electrical connection
3. Flame detector weak or defective
4. Lens dirty or sight tube obstructed
5. If the programmer lockout switch has not trip-
ped, check the limit circuit controls, interlock,
or blower motor
6. If the lockout switch has tripped;
a) Check fuel lines and valves
b) Check flame detector
c) Visually check appropriate timer and relay
contacts, (refer to program control manual)
d) Check blower motor and all interlocks
(CB-40)
e) Lockout switch malfunctioning
1) Stuck contacts
7. Improper air-fuel ratio (lean fire)
a) Slipping linkage
b) Damper stuck open
c) Fluctuating fuel supply
1) Temporary obstruction in fuel supply
2) Temporary drop in gas pressure
8. Interlock device inoperative or defective
F. DAMPER MOTOR
DOES NOT OPERATE
1. Damper positioning switch m wrong position
2. Linkage loose or jammed
3. Motor does riot drive to open or close during
pre-purge or close on burner shutdown
a) Check appropriate contacts (See bulletin)
4. Motor does not operate on demand
a) Damper positioning switch in wrong posi-
tion
b) High-low fire control improperly set or in-
operative
c) Check appropriate contacts (See bulletin)
5. Motor inoperative
a) Loose electrical connection
b) Faulty damper motor transformer