Modine Manufacturing DJE Installation And Service Manual page 18

S S E E R R V V I I C C E E I I N N S S T T R R U U C C T T I I O O N N S S
Access to the temperature sensing bulb, which is positioned
between two heat exchanger tubes at the center of the
furnace can be made through the downstream field installed
access panel. Before removing bulb from mounting bracket,
note position of bulb relative to bracket, then remove. Inspect
temperature sensing bulb to be sure it is straight. When
positioning bulb, care should be taken to place it in the
defective bulb's original position in the center between the two
exchanger tubes. The long tubing between the sensing bulb
and the switch mechanism should be placed to protect it from
cuts, blows, wear due to vibration, etc. The rubber grommet
should be replaced to prevent air leakage and damage to
switch tubing.
I I M M P P O O R R T T A A N N T T N N O O T T E E : : T T h h e e l l i i m m i i t t c c o o n n t t r r o o l l ( ( o o v v e e r r h h e e a a t t s s w w i i t t c c h h ) ) o o n n t t h h i i s s
d d u u c c t t f f u u r r n n a a c c e e w w i i l l l l s s h h u u t t o o f f f f t t h h e e g g a a s s s s h h o o u u l l d d e e x x c c e e s s s s i i v v e e d d i i s s c c h h a a r r g g e e
t t e e m m p p e e r r a a t t u u r r e e s s o o c c c c u u r r . . D D o o n n o o t t a a t t t t e e m m p p t t t t o o c c o o n n t t r r o o l l t t h h e e f f a a n n ( ( b b y y
o o t t h h e e r r s s ) ) w w i i t t h h t t h h e e l l i i m m i i t t c c o o n n t t r r o o l l . . A A n n y y c c h h a a n n g g e e i i n n w w i i r r i i n n g g t t o o a a t t t t e e m m p p t t
t t o o c c o o n n t t r r o o l l t t h h e e f f a a n n w w i i t t h h t t h h e e l l i i m m i i t t c c o o n n t t r r o o l l w w i i l l l l r r e e s s u u l l t t i i n n a a
h h a a z z a a r r d d o o u u s s c c o o n n d d i i t t i i o o n n a a n n d d v v o o i i d d t t h h e e w w a a r r r r a a n n t t y y . .
T T o o p p r r e e v v e e n n t t u u n n n n e e c c e e s s s s a a r r y y r r a a p p i i d d c c y y c c l l i i n n g g a a n n d d d d a a m m a a g g e e t t o o c c a a p p i i l l l l a a r r y y
t t u u b b e e m m a a k k e e s s u u r r e e t t h h e e c c a a p p i i l l l l a a r r y y t t u u b b e e d d o o e e s s n n o o t t t t o o u u c c h h t t h h e e h h e e a a t t
e e x x c c h h a a n n g g e e r r . .
T T o o R R e e m m o o v v e e B B u u r r n n e e r r ( ( R R e e f f e e r r t t o o F F i i g g . . 1 1 2 2 a a n n d d 1 1 3 3 ) )
1. Turn off power and gas supply to unit.
2. Disconnect the pilot supply line and thermocouple leads
from the gas valve. (If unit is supplied with intermittent
pilot ignition, remove ignition and sensor cable from
control module in addition to removing pilot tubing at gas
valve). See Figure 12.
3. The burner may be removed from either side of the duct
furnace. To remove the burner, remove all of the sheet
metal screws holding the side burner access panel in
place. (N N O O T T E E : : with the side access panel screws
removed, the access panel is free to move, be careful not
to drop the panel.)
4. Remove the side access panel to expose the furnace
burner assembly.
5. Carefully thread the pilot tube and thermocouple leads
thru the combustion air slot (at the rear of the unit) into
the burner box so they may be drawn out with the burner.
6. Slide the complete burner assembly out of the burner box.
The complete burner and pilot assembly are now free for
service (see Figure 13).
7. To replace the burner, follow the above steps in reverse
order, being careful to align the burner assembly properly
on the alignment pins on the access panels on both sides
of the duct furnace (see Figure 12).
F F i i g g u u r r e e 1 1 2 2
BURNER
ALIGNMENT
PINS
1 1 8 8
PILOT TUBE
THERMOCOUPLE
LEAD
BURNER SIDE ACCESS PANEL
B B l l o o c c k k e e d d V V e e n n t t S S a a f f e e t t y y S S w w i i t t c c h h ( ( B B V V S S S S ) )
! WARNING
D D o o n n o o t t r r e e s s e e t t u u n n i i t t u u n n t t i i l l v v e e n n t t p p i i p p e e i i s s i i n n s s p p e e c c t t e e d d a a n n d d c c l l e e a a r r e e d d o o f f
a a n n y y o o b b s s t t r r u u c c t t i i o o n n s s . . U U n n i i t t w w i i t t h h b b l l o o c c k k e e d d v v e e n n t t c c o o u u l l d d c c a a u u s s e e
p p e e r r s s o o n n a a l l i i n n j j u u r r y y o o r r d d e e a a t t h h . .
A BVSS is supplied on all gravity-vented duct furnaces and is
designed to prevent operation of the main gas burner if the
venting system is blocked.
If the BVSS has tripped, turn off the gas and electric supply to
the duct furnace. Check the entire vent system connected to
the duct furnace for blockage or damage.
In the case of a restricted vent, there may not be enough
dilution air to carry away the heat radiating off the heat
exchanger to top (and surrounding area), the BVSS may
exceed the temperature setting and trip.
Spillage will also cause the BVSS to trip. If spillage exceeds
five minutes, even though the vent is in compliance with the
NFGC, some type of change must be made in the vent system
to stop the spillage. These changes (improvements) could be
lengthening the vertical vent run, reducing the horizontal vent
run, insulating the vent pipe, using a larger diameter vent pipe,
or using a less restrictive vent terminal.
If these changes do not stop the spillage or the installer
chooses not to make changes, a power venter is really the
only recommended fix (see bulletin 6-530.11).
Low ambient installations can also be a cause for extended
spillage. Be aware that in these installations for freeze
protection and/or condensate protection, there is a good
chance that a power venter will be necessary.
In instances where the blocked vent safety switch trips
repeatedly, refer to Figure 14.
After the vent system has been cleared, or if no blockage or
damage is found in the vent system, the blocked vent switch
may be reset. To reset the blocked vent switch, locate switch
on top of draft diverter and depress the reset button located
on the switch.
With the switch reset, turn on the electric and gas supply to
the duct furnace and restart the unit. Carefully observe the
operation of the unit to assure that it is operating correctly. If
the block vent switch does not allow the unit to function, or
trips after the unit has operated for a period of time, call a
qualified service agency to service the equipment. D D o o n n o o t t
a a t t t t e e m m p p t t t t o o b b y y p p a a s s s s t t h h e e b b l l o o c c k k e e d d v v e e n n t t s s a a f f e e t t y y s s w w i i t t c c h h . . D D o o n n o o t t
a a t t t t e e m m p p t t t t o o r r e e p p l l a a c c e e a a d d e e f f e e c c t t i i v v e e b b l l o o c c k k e e d d v v e e n n t t s s w w i i t t c c h h w w i i t t h h a a n n y y
s s w w i i t t c c h h o o t t h h e e r r t t h h a a n n t t h h a a t t s s u u p p p p l l i i e e d d b b y y t t h h e e d d u u c c t t f f u u r r n n a a c c e e
m m a a n n u u f f a a c c t t u u r r e e . .
F F i i g g u u r r e e 1 1 3 3
PILOT
ASSEMBLY
BURNER
ASSEMBLY
5H73080A
GAS
VALVE
PILOT TUBE
THERMOCOUPLE LEAD