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5 2 | Bosch 96% AFUE Gas Furnace
15 Service and Maintenance Procedures
WARNING: ELECTRICAL SHOCK, FIRE OR EXPLOSION HAZARD
Improper servicing could result in dangerous operation, serious
injury, death or property damage.
Before servicing, disconnect all electrical power to furnace.
When servicing controls, label all wires prior to
disconnecting. Reconnect wires correctly.
Verify proper operation after servicing.
WARNING: FIRE, EXPLOSION OR CARBON MONOXIDE
POISONING HAZARD
Failure to replace with proper control could result in fi re,
explosion or carbon monoxide poisoning.
Replace ONLY with the same model number or as specifi ed
by the manufacturer.
15.1 Annual Inspection
The furnace must be inspected by a qualifi ed installer or service agency at least
once per year. Inspect the furnace at the beginning of the heating season. This
will ensure that all furnace components are in proper working order and that the
heating system functions appropriately. Pay particular attention to the following
items. Repair or service as necessary.
a.
All fl ue gas carrying areas external to the furnace (i.e. chimney, vent
connector, vent pipe) are clear and free of obstructions.
b.
Check for any loose wiring, and correct as needed.
c.
Inspect heat exchangers and blowers for corrosion, deterioration, or
deposits of debris. Remove any obstructions.
d.
The vent connector is in place, slopes upward and is physically sound
without holes or excessive corrosion.
e.
The return-air duct connection(s) is physically sound, is sealed to the
furnace cabinet, and terminates outside the space containing the furnace.
f.
The physical support of the furnace is sound without sagging, cracks, gaps,
etc. around the base so as to provide a seal between the support and the
base.
g.
There are no obvious signs of deterioration of the furnace.
h.
The pilot and burner fl ames are in good adjustment (by comparison with
pictorial sketches or drawings of the main burner fl ame and, if applicable,
the pilot burner fl ame, refer to the Installation, Operation, and Maintenance
Manual for more information).
i.
Check the condensate drain and trap for leaks and cracks. Fill the trap with
water. Clean the drain and trap. The trap must be fi lled with water and the
drain and trap should be cleaned.
Data subject to change
15.2 Filters
A return air fi lter is not supplied with this furnace; however there must be a
means of fi ltering the return air. The installer must supply fi lter(s) at the time of
installation.
Filter maintenance
Improper fi lter maintenance is the most common cause of inadequate heating or
cooling performance. Clean permanent fi lter or replace disposable fi lter once a
month or more frequently as required. When replacing a fi lter, it must be replaced
with a fi lter of the same type and size.
Become familiar with fi lter location and procedures for removal cleaning and
replacing them. If help is needed, contact the installer of the furnace or a qualifi ed
service person.
Filter removal
Depending on the installation, diff ering fi lter arrangements can be applied. A media
air fi lter or electronic air cleaner can be used as an alternate fi lter.
Follow the fi lter sizes given in the Recommended Minimum Filter size (Table 2, page
22) to ensure proper unit performance.
For further details, see your distributor.
Upright fi lter removal
To remove fi lters from an external fi lter rack in an upright upfl ow installation, follow
the directions provided with external fi lter rack kit.
Clean, wash and dry a permanent fi lter. When using a permanent fi lter, both
sides should be sprayed with a dust adhesive as recommended on the adhesive
container. Spray adhesives for use with permanent fi lters can be found at some
hardware stores. BE SURE AIRFLOW DIRECTION ARROW POINTS TOWARDS THE
BLOWER.
Inspect fi lter. If your dirty fi lter is the disposable type, replace dirty fi lter with the
same type and size fi lter. If your dirty fi lter is a permanent fi lter, clean as follows:
Clean, wash, and dry a permanent filter. When using a permanent filter,
both sides should be sprayed with a dust adhesive as recommended on
the adhesive container.
If badly torn or uncleanable, these filters must be replaced by equal
size permanent, high velocity filters. Throwaway filters must not be
used as replacement for permanent filters.
15.3 Induced Draft And Circulating Blower Motors
The bearings in the induced draft blower and circulator blower motors are
permanently lubricated by the manufacturer. No further lubrication is required.
Check motor windings for accumulation of dust which may cause overheating.
Clean as necessary.
15.4 Flame Sensor (Qualifi ed Service Technicians Only)
Under some conditions the fuel or air supply can create a nearly invisible coating
on the fl ame sensor. This coating acts as an insulator causing a drop in the fl ame
sense signal. If the fl ame sense signal drops too low, the furnace will not sense the
fl ame and will lock out. The fl ame sensor should be carefully cleaned by a qualifi ed
service technician using emery cloth or steel wool. Following cleaning, the fl ame
sense signal should be 1 to 6 microamps at 115 volts.
Installation, Operation & Maintenance
04.2019 | Bosch Thermotechnology Corp.
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