Cautions; Furnace Removal - Suburban NT-12S Service Manual

A yearly inspection should be made of all gaskets on the furnace. If any gaskets show signs
of leakage or deterioration, they must be replaced to assure proper pressurization of the
sealed combustion chamber.
Motors used on RV furnaces are permanently lubricated and do not require oiling.
1. Never operate the furnace with the electrode wire disconnected or with the electrode
assembly removed from the furnace.
2. Never use a battery charger to checkout an electronic ignition furnace -use a 12-volt
battery.
3. Never use a screwdriver or any part of the electrode assembly while the furnace is in
operation.
4. Be certain that the spark from the electrode never reaches the flame sensor portion of
the electrode assembly. (See Figure 2 for correct gapping).
5. Be sure the electrode assembly screws are snug at all times, especially after the
electrode has been removed and reinstalled.
6. If the module board is found to be defective, it must be replaced - it is not field
repairable. Any attempts to repair the board may alter the board and cause it to
operate in an unsatisfactory manner.
7. Ensure that the gap between electrode and ground is always 1/8". The gap between the
ground and the flame sensor should be approximately twice the gap between electrode
and ground to ensure no sparking to sensor. Sparking to sensor will damage the
module board (see Figure 7).
To replace parts or service the latter generation furnaces, the M and S series, it is
necessary to follow these steps:
1. Disconnect gas and power supply.
2. Remove vent cap assembly (4 sheetmetal screws and one 3" exhaust baffle screw, see
Figure 2).
3. Remove the cabinet front.
4. Remove the shipping screw securing the chamber shield to the cabinet.
5. Pull chamber outward completely to gain access to all controls and parts for adjustment
or replacement.
NOTE: Our service technicians are available to assist you in making repairs or parts
replacements from 8:00 a.m. to 5:00 p.m. EST, Monday through Friday (except holidays),
by calling (615) 775-2131.

CAUTIONS

FURNACE REMOVAL