Modine Manufacturing DJE Installation And Service Manual page 21

S S E E R R V V I I C C E E D D I I A A G G N N O O S S I I S S
F F i i g g u u r r e e 1 1 9 9 – – F F l l a a m m e e R R o o l l l l o o u u t t A A p p p p e e a a r r a a n n c c e e
6. Flame Rollout. Flames rolling out of the combustion air
inlets when the burner is turned on can create a fire
hazard, scorch unit finish, burn wires, or damage controls.
Gas in the burner mixer may be ignited, producing
flashback. Flame rollout is a variation of floating flames,
with flames reaching for air outside the combustion
chamber. Basic cause is lack of combustion air that may
be due to overfiring, poor draft, or flue blockage.
F F i i g g u u r r e e 2 2 0 0 – – P P i i l l o o t t a a n n d d B B u u r r n n e e r r
PILOT
BURNER
PILOT
ORIFICE
S S t t a a n n d d i i n n g g P P i i l l o o t t S S y y s s t t e e m m s s
I I f f P P i i l l o o t t D D o o e e s s N N o o t t L L i i g g h h t t
1. Check gas supply to pilot.
2. Bleed air from pilot line (Use special care in bleeding
propane units.)
3. If pilot sputters, check pilot line for condensation or other
obstructions.
4. If flame is feeble or short, check pilot orifice for
cleanliness. Replace if necessary. Do not enlarge orifice.
5. Be sure thermocouple contact point is clean. If problem
persists, replace thermocouple and/or pilot safety valve.
6. If the above steps do not correct the condition, consult
your local gas company.
! CAUTION
Do not attempt to reuse ignition controllers which have
been wet. Replace defective controller.
THERMOCOUPLE
I I f f S S t t a a n n d d i i n n g g P P i i l l o o t t D D o o e e s s N N o o t t S S t t a a y y L L i i t t
1. Check manifold pressure with all units operating making
certain that there is proper pressure.
2. Check pipe or tubing size to unit. See Table 8.
3. Be sure all pilot connections are tight.
4. Check for excessive drafts.
5. Check for clogged pilot orifice or pilot line.
6. Check for leaks around pilot fittings. If leaks cause flame
impingement on thermocouple lead, thermocouple may
become inoperative.
E E f f f f e e c c t t o o f f P P i i l l o o t t O O p p e e r r a a t t i i o o n n o o n n S S a a f f e e t t y y C C o o n n t t r r o o l l s s
1. A weak pilot flame may cause poor ignition or reduce heat
on thermocouple to the point where the automatic controls
become inoperative, thereby shutting off gas supply to
main burners. This may result from a plugged orifice, dirty
pilot valve or poor adjustment.
2. Check electrical connections from the thermocouple
element to the safety valve to assure good electrical
contact. Also check location of pilot flame in relation to
thermocouple element.
I I f f M M a a i i n n B B u u r r n n e e r r s s D D o o N N o o t t L L i i g g h h t t
1. Check gas supply to burners.
2. Bleed air from pipe lines.
3. Be sure pilot is lit, correctly positioned and strong enough
to ignite burner ports.
4. Check wiring (electric power supply) to automatic gas
valve.
5. If the above does not correct the condition, consult your
local gas company.
I I n n t t e e r r m m i i t t t t e e n n t t P P i i l l o o t t I I g g n n i i t t i i o o n n S S y y s s t t e e m m s s
1 1 . . P P i i l l o o t t w w i i l l l l n n o o t t l l i i g g h h t t o o r r s s t t a a y y l l i i t t . .
P P o o s s s s i i b b l l e e C C a a u u s s e e
1a. No spark at ignitor. 1a. Check connections. Check for proper
1b. Defective flame 1b. Check milliamps of sensor. Clean
sensor or loose
connections to flame
sensor.
1c. Pilot valve electrical 1c. Tighten connections.
connections loose.
1d. Replace.
1d. Defective pilot valve.
1e. Check grounding means.
1e. Poor ground
connections.
1f. No power from 1f. Check transformer voltage on
control transformer.
1g. Spark not located in 1g. Correct or replace pilot.
pilot gas stream.
1h. Dirty or plugged pilot 1h. Clean or replace.
orifice.
1i. Pilot line kinked or 1i. Correct or replace pilot line.
obstructed.
1j. Pilot flame too low. 1j. Check pilot flame and adjust per
1k. Flame sensor out of
1k. Reposition.
position.
1l. Defective ignition
1l. Replace.
controller.
P P o o s s s s i i b b l l e e R R e e m m e e d d y y
spark gap, cracked or broken
electrode ceramic, blown controller
fuse or brittle, cracked or loose high
tension cable. Check power
exhauster pressure switch. Replace if
defective.
sensor with steel wool. Tighten loose
connections. Replace flame sensor if
necessary.
secondary side for 25v.
valve manufacturer's
recommendations.
2 2 1 1