Thomas & Betts EEDU - Manual (Page 22)

Form 421, Page 22
SERVICE AND MAINTENANCE
WARNING: If you turn off the power supply,
turn off the gas. See Hazard Levels, page 2.
Maintenance Requirements -- Like all quality equipment, this unit
will operate with a minimum of maintenance. However, to ensure long
life and satisfactory performance, the following service schedule is rec-
ommended. When servicing, follow standard safety procedures and
those specific instructions and warnings in this manual.
Furnaces should be inspected at the beginning of each heating season
and then once every four (4) months where the equipment is working
under normal conditions. If the furnace is located where an unusual
amount of dust or soot or other impurities are contained in the air,
more frequent inspection is recommended. Clean the heat exchanger
(inside and outside) annually.
28. Burner Rack Removal Instructions
1. Turn off the gas supply.
2. Turn off the electric supply.
3. Remove bottom rear panel (located on the manifold side of the fur-
nace) by removing the two screws from each side.
4. Mark and disconnect electric valve leads.
6. Uncouple the union in the gas supply.
7. Remove two sheet metal screws in the bottom of the burner rack
assembly.
8. Pull "drawer-type" burner rack out of the furnace.
To disassemble the burner rack:
1. Remove flash carryover system (screws located at rear of burner
drawer).
2. Remove burner hold down clamp (located inside burner drawer un-
derneath the pilot).
3. Pull main burners horizontally away from injection opening and
lift out.
Follow the instructions in Paragraph 29 to clean. To re-assemble and
replace, reverse the above procedures being careful not to create any
unsafe conditions.
29. Cleaning Pilot and Main Burners
Pilot - The pilot is located under the aeration panel on the control end
of the burner tray and is accessible only after the burner rack assembly
has been removed. In the event the pilot flame is short and/or yellow,
check the pilot orifice for blockage caused by lint or dust accumula-
tion. Remove the pilot orifice and clean with air pressure. DO NOT
REAM THE ORIFICE. Check and clean the aeration slot in the pilot
burner.
Clean the metal sensing probe and the pilot hood with an emery cloth
and wipe off the ceramic insulator. Check the spark gap; spark gap
should be maintained
to .100". After the
pilot is cleaned, blow
any dirt away with
compressed air. The
combination valve
includes a pilot ad-
justment screw. To
adjust, remove cap
screw and adjust the
pilot flame to ap-
proximately 1-1/4".
Pilot System - No periodic maintenance of the ignition control box
is required. However, each season the lead wires should be checked for
insulation deterioration and good connections. Proper operation of the
electronic spark ignition system requires a minimum flame signal of
0.2 microamps as measured by a microampmeter. Do not attempt to
disassemble the ignition controller. There are no field replaceable com-
ponents in the control enclosure.
CAUTION: Due to high voltage on pilot spark
wire and pilot electrode, do not touch when
energized. See Hazard Levels, page 2.
Burners - Normally it is unnecessary to clean the main burners but
during the annual cleaning of the heat exchanger tubes it is wise to
inspect the burners for plugged ports. Main burners may be cleaned
using air pressure. Use an air nozzle to blow out scale and dust accu-
mulation from the burner ports. Alternately blow through the burner
ports and the venturi. Use a fine wire to dislodge any stubborn par-
ticles. Do not use anything that might change the port size.
Clean the burner rack flash carryover systems with air pressure.
Figure 21 - Pilot Burner Spark Gap
Figure 22 --
Vertical Spark
Pilot
Figure 23 - Pilot Location
of burner
3/4"
(+ or - 1/32")
Burner
Rear
Support
of pilot and
sensor
2-3/4"
NOTE: Use only factory-authorized replacement parts.
CAUTION: When cleaning, wearing eye
protection is recommended.
When re-installing
the pilot, be sure to
include the pilot
hole cover plate.
Burner Orifices for Sea Level Operation
Size Qty Natural Gas Propane Gas
Drill Size P/N Drill Size P/N
75 4 45 38678 1.2 mm 63003
100 4 41 11792 1.45 mm 61652
125 5 41 11792 1.45 mm 61652
140 5 38 45870 1.55 mm 61653
170 6 38 45870 1.55 mm 61653
200 7 38 45870 1.55 mm 61653
225 8 38 45870 1.55 mm 61653
250 9 39 45871 1.55 mm 61653
300 11 39 45871 53 9789
350 13 39 45871 53 9879
400 15 39 45871 53 9879