Kenmore Condensing gas furnaces Guide

your
oIng
from
ing,
St ,
® If: _
• R_FERENCF-
SAVE THiS MANUAL FOR FUTURE _

SERVICE TECHNICIAN CHECK_
'When the furnace is being inspected for:c0ndition
and operation have the Service Technician check the
following items.
For additional information the Service Technician
can consult the installation instructions and ap-
plicable service manual for the furna'ce.
1. Check for adequate combustion air being sup-
plied to the furnace area and all air openings in-
to or from the furnace.
2. Check all flue gas passages including main and
pilot burners, heat exchanger, and vent pipe.
3. Check gas pipe and all connections inside and
leading to the furnace for leaks.
4. Check electrical wiring and connections.
5. Check supply and return air ducts for leakage,
blockage and connections to-furnace,
.Check circulating air blower wheel and motor,
clean and lubricate if required,
7. Perform: an Operational checkout on the furnace
tO :be sure safety: c0nt¢ols function and that fur-
nace oper_te_ _r0perly. ' ....
FREEZING TEMPERATURES
AND YOUR HOME
Your furnace is equipped with safety devices that may
keep it from operating if there are any abnormal con-
ditions affecting the furnace and L.P. models may not
operate if there is even a brief or slight interruption
in the electric power or gas supply,
tf your furnace remains shut down long enough dur-
ing freezing temperatures, for water pipes to freeze
it could result in serious water damage,
tf your home will be unattended during this time you
should take these precautions.
1. Shut the water off at the main inlet into your home
anddrain the water lines if possible,
2. Have someone check your home as often as
necessary for temperature conditions that could
cause water damage. Suggest they call a qualified
service agency if required,

COMBUSTION AIR/INDOOR ,HUMIDITY
(How. They Affect Your Safety and Comfort)
.! An energy efficient home or ahome using exhaus_
fans, fireplaces, clothes dryers, and gas appliances in-
creases this problem and your appliances could be
starving for air, which is unsafe.
This'_ay result in more and more air being drawn from
the house until fresh air is sucked in through an ap-
pliance flue or fireplace chimney. Carbon monoxide
can be the result.
J
Your home needs to breathe and the different
temperatures and humidity ranges in your home dur-
ing the year makes it necessary to be sensitive to air
requirements and potential ventilation problems.
Because of high energy costs for home heating,
new materials and methods are being used in con-
struction and remodeling. The improved construction
and additional insulation has made these homes much
tighter around windows and doors so that air leakage
is minimal. This may create aproblem in supplying
enough combustion and ventilation air for gas-fired or
other fuel burning appliances. Fresh air is needed for
combustion and ventilation of flue gases.
Carbon monoxide or "CO" is a colorless and odorless
gas produced when fuel is not burned completely or
when the flame does not receive sufficient oxygen.
CARBON MONOXIDE CAN RESULT IN
ASPHYXIATION.
Be aware of these air starvation signalsi
1. Headaches-Nausea-Dizziness
2. Excessive humidity-Heavily frosted win-
dows or a moist "clammy" feeling in the
home.
3. Smoke from the fireplace won't draw up
the chimney.
4. Flue gases ,won't draw up the appliance
flue pipe.
1. How do I know if my furnace or other appliances are receiving enough
air for proper combustion and ventilation of flue gases?
Use the following checkout procedure to determine
if the air leakage into your home is adequate tosupp-
tyth e needs of your appliances and fireplace. If you
are uncertain about your ability to perform these
checks contact your installing dealer or place of
purchase.
5. Check for draft hood spillage at each appliance.
(Hold a lighted_matCh 2" from draft opening as :
shown for the:typical gas water heaterii :
FIG. 1 CHECK :FOR DRAFT HOOD SPILLAGE
A.
1.
Make the inspection as follows:
Close all doors and windows. If you have a
fireplace, start a fire and wait until flames are bur-
ing vigorously.
2. Turn on all exhausting devices, such as: kitchen
and bathroom exhaust fans - dryers (gas or
electric)
3. Turn on all vented gas appliances, such as: heating
equipment (includes any room heaters) water
heaters.
4. Wait ten (10) minutes for drafts to stabilize.
B. No Spillage -
if match flame pulls toward draft hood, this in-
dicates sufficient infiltration air. Return exhausting
devices and appliances to the condition you found
them.

}.- -: :>:h _ :i:/;,:'=; _ ':
"I:!S;I;!, _Lii_:i;_:_:_i_:_ :_'
Combustion Air iAdoor Humidity (Cont.)
C. Drafthood Spillage - _ _::_:
If there is spillage at a draft hood - (rfi_ch goes
out or flame wavers away from draft'Jiood):
1. Check for plugged flue connectors and chimneys.
Check and repair stoppage and test again.
2. if you have a fireplace, open awindow or door
near the fireplace and then check for spillage.
a. If spillage stops, do not use the fireplace until
you can supply fresh air by a permanent duct.
3. If you have kitchen and bathroom exhaust fans
turn them off and check for spillage.
a. If spillage stops, do not use exhaust fans until
you can supply fresh air by apermanent duct.
Circuit breakers for fans should be turned off.
4. Spillage means air starvation and a fresh air duct
or air intakes must be installed to provide air
directly to the furnace or other gas appliance.
These must comply with local and state building
codes or in their absence with the National Fuel
Gas Code NFPA 54/ANSI Z223.1, current edition.
2. What is Relative Humidity and how do I know if it is tOo high or low?
Relative humidity is the amount of water vapor in the air
relative to the amount the air can hold at the same tempera-
ture. Example: At 40% relative humidity, the air can hold
60% more moisture before it is saturated.
The colder the air, the less moisture it can hold. As air is
warmed, its ability to hold moisture is increased. Example;
A winter day, outdoor temperature 10°F, and relative
humidity of 70%. If that air enters ahome and is warmed
to 72°F the relative humidity will drop to 6% (very dry) if
no more moisture is added.
Relative humidity is important to your health and home as
proper humidification helps cut down on incidences of
respiratory illness and helps keep air cleaner and fresher.
HAS YOUR FURNACE BEEN REPLACED?
This furnace is very efficient and has amuch smaller vent
(flue) pipe with a brower in the venting system.
The smalMr vent and blower increases the efficiency of the
furnace but they will also decrease the amount of natural
air infiltration into the house. This is because less air will
escape up the vent system during the off cycle so less cold
dry air will enter the house by it_fllteration, This in conjunc-
tion with other items may cause the humidity to raise to
uncomfortable levels. This condition can usually be elimi-
nated by minor changes in everyday routines, see "If
Humidity Is Too High".
VISUAL METHODS OF GAUGING INDOOR
HUMIDITY:
• Frequent fogging or excessive condensation on inside
windows indicates the indoor humidity level is too high
for outdoor weather conditions. Damage to the buiiding
may result if the condition persists. (Condensation on in-
side of storm windows indicates loose inside windows.
Adding weatherstripping to tighten inside windows
usually corrects this problem.)
A good relative humidity is one just high enough to barely
start condensation along the lower edges or tower corners
of the windows. More than that can be damaging°
IF HUMIDITY IS TOOHiGH,I. '_!'"
Condensation occurs when Warm; moist air Cdntacts a_c6o!
surface (window or outside wall, for,example), add drops of
water or acoating of frost form. The c05densation problem
increases as the outside temperature decreases.
A high humidity level usually result sfr0i:n bathing or cook-
ing, etc. Suggestions for correcting this problem:
1. Turn down or discontinue use of humidifier.
2, Use range and bathroom exhaust fans while cooking and
bathing or open a door or window for afew minutes to
bring in cool dryer air.
3. Cook with pans covered.
4. Take shorter baths or showers with cooler water.
5. Install afresh air intake duct. Cold, dry air brought in
from outside to the furnace area lowers the indoor
humidity_level.
6. ffthe above measures do not correctthe problem, have
appliances checked. A rmalfunctioning appliance can
contribute water vapor to the house,
7. -if the above items do not correct the problem consult
a heating contractor about adding aheat recovery ven-
tilator or afr to air heat exchanger.
RECOMMENDED INDOOR HUMIDITY:
Use the following table as a guide. It shows the recommend-
ed maximum indoor humidity in relationship to the outdoor
temperature.
TEMPERATURE HUMIDITY
•Drop three ice cubes into a glass of water and stir. If,
within three minutes, moisture does not form on the
glass, the air is too dry and a humidifier would be
beneficial. (Do not perform this test in the kitchen, as
cooking vapors may produce inaccurate results.)
+20°E and above 35%
+10"F 30%
0°F 25%
-10°F 20%
-20°F 15%
4

YOUR FURNACE
Condensing furnaces have ahigher efficiency rating
than conventional gas furnaces, but are basically the
same in design and operation, The major difference
is the addition of a secondary heat exchanger which
captures heat that would normally go out the furnace
vent pipe,
By capturing this heat the flue gases are cooled to a
point where most of the vapor' (mainly water) con-
denses out and must be drained away, Because the
gases are cooled down plastic pipe is used for the vent
pipe in place Of metal.
The following paragraphs and Illustration wil! help you
to understand the main parts of your furnace and how
they operate.
DOOR INTERLOCK SWITCH
All of the electrical power for the furnace goes through
the Door Interlock Switch and the furnace will not
operate if the Blower Door is not properly in place.
ELECTRICAL
JUNCTION/CONTROL BOX
System Relay
Fan Relay
Transformer-1 15V to
DOOR INTERLOCK SWITCH
EXHAUST TEMPERATURE
LIMIT SWITCH
COMBUSTION AIR
BLOWER
FAN/LIMIT CONTROL
ELECTRONIC SPARK
MODULE
FLAME ROLLOUT
SPARK IGNITOR/PILOT BURNER
OR HOT SURFACE IGNITOR
AND MAIN BURNERS INFORMATION LABELS
Safety & Service Clearances
Lighting Instructions (inside or on
Back Side of Door Panel)
Rating Plate FIG. 2
TYPICAL COUNTERFLOW
CIRCULATING AIR BLOWER
AIR PROVING SWITCH
SECONDARY HEAT EXCHANGER
PRIMARY HEAT EXCHANGER
White Rodgers Valve - 36 E Series
Hot Surface Ignition
@
Honeywell Valve - 8204 Series
Spark to Pilot Ignition

Your Furnace (Cont.)
AIR PROVING SWITCH
LIMIT CONTROL
IGNITOR/SENSOR
COMBUSTION AIR BLOWER
EXHAUST TEMPERATURE
UMIT SWITCH
ELECTRICAL JUNCTION
BOX
DOOR INTERLOCK
ELECTRICAL CONTROL BOX
SYSTEM RELAY
FAN RELAY
TRANSFORMER-115V - 24V.
White Rodgers Valve 3'6 i i
- E Series
Hot Surface ignition
Honeywell Valve _8204 Series
Spark to Pilot ignition
PRIMARY HEAT EXCHANGER
GAS VALVE
FLAME ROLLOUT SENSOR
SECONDARY HEAT
EXCHANGER'
FAN CONTROL
ELECTRONIC SPARK
MODULE
CIRCULATING AIR BLOWER
FILTER (SHOWN IN BOTTOM)
MAY BE MOUNTED IN SIDE
THE OSTAT FIG, 3
TYPICAL UPFLOW
See separate description under "Thermostat". As the
temperature in your home drops the thermostat closes
and completes a tow voltage (24V) control circuit to
the System Relay inside the control I_ox. This relay
closes and provides power to the Electronic Ignition
Module, and Combustion Air Blower. The thermostat
also completes a circuit to an internal heater inside
the Fan/Limit Control. This allows more precise Fan
"ON" control to help maintain comfortable
temperatures in your home.
ELECTRONIC SPARK
MODULE/GAS VALVE
When the thermostat calls for heat it completes a Low
voltage (24V) circuit to the electronic ignition module.
The module either starts an electric spark or activates
a hot surface ignitor to ignite the gas as the gas valve
opens letting gas through to pilot or main burner.
When the flame is firmly established the module will
shut off. For safety it will automatically restart if the
flame is interrupted. !f there is an abnormal function,
the gas valve is designed to automatically shut off the
gas.
COMBUSTION AIR BLOV#ER
The System Relay closes to start the Combustion Air
Blower which exhausts the vent gases out through
the vent pipe. The blower creates a pressure differen-
tial inside the furnace which provides the right amount
of induced draft (air) to properly control combustion
for maximum efficiency. This part of the system pro-
vides several safety features as the electrical circuit
for the Electronic Ignition Module/Gas Valve must go
through a Flame Rol! Out Sensor, Air Proving Switch,
Exhaust Temperature Limit Switch and the
temperature limit portion of the Fan/Limit Control.
If the right amount of air is not going through the fur-
nace or if temperatures are too hot the electrical cir-
cu=t to the Electronic Ignition Module/Gas Valve will
be interrupted.
6

Your Furnace (Cont.)
CIRCULATING AIR BLOWER
The blower to circulate room air through the furnace
starts as soon as the internal.heater in the Fan/Limit
control causes the fan switch portion to close com-
pleting the electrical circuit.
It shuts off when the Fan/Limit Control opens the elec-
trical circuit. This means the blower comes on approx-
imately 30 seconds after the fu'rnace first starts and
it continues to run unti] the furnace cools down. This
helps to achieve the maximum comfort and efficien-
cy. from your furnace.
FAN RELAY
This relay provides electric power to the Circulating
Air Blower for continuous blower operation (Ther-
mostat Fan Switch set to "FAN ON") and for the
blower to run if central .air conditioning is installed.
FAN/LIMIT CONTROL
The Fan/Limit Contro! provides power to the Cir-
culating Air Blower to keep it on, until the furnace
cools down. The limit portion provides safety because
it will open the low voltage control circuit, shutting
the furnace down if it gets too hot.
The fan off setting can be adjusted if the fan remains
on long enough that cool drafts are felt in the room
after the furnace shuts off. Contact a Qualified Ser-
vice Technician.
DRAIN TRAP ASSEMBLY
The drain trap has a float in it, that will cause the fur-
nace to shut down if the drain lines become
obstructed. If this happens the trap and lines must be
taken apart and cleaned. See "Condensate Disposal'"
page 10.
Thermostat
Your furnace will not operate properly without agood
quality, correctly installed thermostat. The thermostat
location is very important as it must be sensing
average room temperatures. It must not be exposed
to hot or cold drafts or hot or cold spots on the wall,
such as outside walls or awalt with pipes inside or
openings into attic.
There are many types and styles of thermostats but
the operation is usually similar. BE SURE TO BECOME
FAMILIAR WITH YOUR THERMOSTAT, The simplest
type of thermostat only starts and stops the furnace
to maintain the proper room temperature. The most
widely used types will control both heating and cool-
ing functions and will have a Fan Switch with Auto
and ON settings. On Auto, the Circulating Air Blower
will cycle on/off with the furnace but if, switched to
ON it will run constantly whether or not the furnace
is on.
In addition there are thermostats that automatically
switch from Heating to Cooling and with night set-
backs. The night set-back, or multiple set-back type,
will lower the temperature at night or during the day
when no one is at home.
HEATING:
Posftion the Thermostat System Switch on HEAT, Set
the Fan Switch to AUTO for the blower to cycle
ON/OFF. Sefect desired temperature setting and fur-
nace will automatically start up and shut off as re-
quired to maintain that setting, Fan Switch may be
positioned to ON for continuous air circulation only
if that position maintains the same or a higher blower
speed so you have the same or greater- airflow.
CAUTION
Continuous Fan ON at too slow of a blower speed may
cause improper furnace operation and possible
damage to the heat exchanger,
HEATING ANTICIPATOR:
For more precise comfort control your thermostat may
have an adjustable Heat Anticipator. (Some are not ad-
justable). For most homes the anticipator should be
set on the value listed in the Tech Data Sheet which
is found in the Furnace Technical Support Manual.
If your furnace cycles ON/OFF with very short-ON in-
tervals or _f the OFF cycle is so long that room
temperatures become uncomfortable the anticipator
setting may need to be adjusted.
To Adjust:
Remove thermostat cover and locate anticipator,
Check ,the setting. !f not on.thesetting recommen_
ed for your furnace, moye the lever to the proper set-'
ting and try it.for a day or two,
To lengthen burner-on time move' the indicator
towards "Longer"_ To decrease burner-on time move
in opposite direction,
ira= ii i ii
NOTE :
To accurately determine the effect do not adjust
more than half ascale marking at a time and
I
iI allow a day between adjustments.
I ii iiiiiiii II II III I ' iiiiiiiiiiiiii
COOLING:
For cooling simply position the system switch to
COOL Instead of HEAT and thermostat will function
in the same manner to control cooling.
7

Operating Your Furnace
Keep the blower access door and upper access panel
in place except for inspection or maintenance. An
automatic switch prevents furnace operation if the
blower door is not in place.
Before starting your furnace be sure you read and
understand all of the procedures in this manual. Check
to make sure the furnace filter is clean and correctly
installed.
STARTING THE FURNACE
See page 5 or 6 for location and illustration of gas
valve.
1. Turn the thermostat to its lowest temperature
setting or to OFF if equipped with a System
Select Switch.
2. Turn Manual Shutoff Valve, in the gas line, to
OFF position, should be a right angle or 90 ° to
gas line.
3. Turn OFF electric power to furnace at disconnect
switch or circuit breaker.
4. Remove furnace access panel, exposing gas con-
trois and burner compartment.
5. Locate gas valve and identify settings.
The valve is marked with ON -- OFF positions.
6. Turn the knob all the way to OFF. Make sure it
has been in OFF for at least 5 minutes before
proceedint].
7. Turn the contrQ! knob to ON (Depress knob to
turn on some Honeywell valves).
Replace access panels and doors.
Turn ON electric power for furnace,
Open the,-Manual Shutoff Valve in the gas4ine,
: ,, ..... .... ,, • , ,.. -
Set therm0stat:to desired temperature-and
System Select Switch to HEAT if equipped.
The furnace witI begin sparkingto ignite the pilot flame
or the hot surface ignitor will heat up to ignite the gas.
When the system verifies a steady flame the ignition
system will shut off.
.
9.
10.
11.
WIHH HOT SURFACE
IGNITION SYSTEM
Furnace will make several attempts to lite before go-
ing into lockout. Each attempt requires alonger time
with the total cycle taking approximately 8-10
minutes.
If air remaining in the tines on a new installation
prevents the furnace from lighting ONE additional cy-
cle may'be tried, tf furnace does not light, turn the
thermostat to its lowest setting. Wait one minute,
then turn it back up abovethe temperature shown on
the thermometer. This starts the ignition cycle over
again. DO NOT REPEAT MORE THAN ONCE. If fur-
nace will not light, call a qualified Service Agency.
TURNING OFF THE FURNACE
1. Set the thermostat to the lowest setting or set
System Select Switch to OFF if equipped.
,_Shouidoverheating occur or the gas supply fail to
shut off, shut off the manual gas valve to the fur-
nace before shutting off the electrical supply.
EXTENDED SHUTDOWN
1. Set thermostat to lowest setting or set System
Select Switch to OFF if equipped.
2. Turn Manual Shutoff Valve to off position, right
angle or 90 Dto gas line.
3. Turn electric power off. (May be left "ON" for
set-back or chronograph type thermostat with
batteries, provided thermostat has a system
select switch to place in the "OFF" position.)
4. Turn the gas valve control knob to "OFF".
Winter Shutdown
tf there is the possibility of freezing temperatures,
remove the Condensate drain trap and empty to pre. *,
vent freezing. ........ ....... ....
L P Model Furnaces
With Spark to Pilot Ignition (System Retries)
The ignition system will spark to light the pilot for 90
seconds. If the pilot does not light within 90 seconds
the system will shut off for 5 minutes and then it will
try again for 90 seconds. It will continue to cycle un-
til the pilot lights, (90 seconds ON/5 minutes OFF).
If the unit does not start after 3 tries or approximate-
ly 20 minutes, shut ,the unit off at the thermostat and
call a qualified Service Agency. ..

FURNACE MAINTENANCE
it is recommended .that you have your furnace in-
spected and serviced on an annual basis (before the
heating season) by a quaUfied service technician.
You may perform maintenance on the furnace
yourself, but remember that certain mechanical and
electrical skills and tools are required to properly per-
form maintenance on the furnace. Personal iniury or
death may result if you are not properly trained. You
should call your installing dealer or place of purchase
if you are uncertain about your ability to perform
maintenance, ,'
Filter Replacement
The fitter will normaliy be found inside the furnace
blower compartment, see pages 5 and 6, but alter-
nate locations may be aremote filter rack attached
to the outside of the furnace, aseparate return air
cabinet attached to furnace or a remote filter grille.
Remote filter grilles and return air cabinets wil! usual-
ly have a hinged door or removable panel to be able
to remove filter. Filter racks attached to the furnace
will usually be made so the filter simply slides out one
side for removal. Use only the same size filter. The
type must be the same unless replacing a disposable
tow velocity type, with awashable high velocity type.
AIR FILTERS -- Monthly
The air fi!ter(s) should be inspected at least monthly
and cleaned or replaced as required. There are two
types of filters most commonly used. The most widely
used is the fiberglass disposable type which should
be replaced before it becomes clogged. The other type
commonly in use is the washable type constructed of
aluminum mesh, foam, or reinforced fibers. Washable
filters may be cleaned by soaking in mild detergent
and rinsing with water.
,NOTE ....
Some filters are marked with an arrow to indicate
the proper direction of air flow through the filter.
"When installing the arrow must point in the direc-
tion of the air flow. Remember that dirty fitters
are the most common cause of inadequate
heating or coo}ing performance.
.immm
The table on page 10 lists recommended sizes and
types of filters that may be used with your furnace,
based on the input rating and nominal tons of air con-
ditioning that may be used with the furnace.
However, the furnace installer may have used a larger
filter for additional air volume or if the furnace was
installed for Heating Only with aremote filter cabinet
or central return he may have installed a smaller filter.
If air conditioning has been added since your furnace
was installed, make sure the filter size is adequate.
Replacement filters should be of the same type and
size to ensure adequate air flow and filtering, unless
a disposable low velocity filter is replaced with a
washable high velocity type.
Filter Replacement/Upflow (Hi-Boy)
See Figure 4
1. Turn off electric power for furnace at circuit
breaker or disconnect switch.
.
3.
.
.
6.
7.
FIGURE 4
Remove blower compartment door.
Pull back on filter clip and remove filter being
careful not to dislodge dirt and debris from filter.
Inspect filter and replace or clean washable type.
If filter is aluminum mesh it should be recoated
wit.h filter coating spray.
Reinstall filter under clips. If filter is marked for air
flow direction make sure it's insta$1ed correctly.
Replace blower compartment door making sure
that it's tightly closed.
Turn on electric power for the furnace.
FILTER REPLACEMENT
?

Furnace Maintenance (Cont.)
Filter ReplacementlCounterflow
See Figure 5
1. Turn off electric power for furnace at circuit
breaker ordisconnect switch.
2. Remove blower compartment door.
3. Reach up through right side and lift upward and
swing top of filter towards center of furnace then
purl filter down and remove being careful not to
dislodge dirt and debris from filter.
4. Inspect filter and replace or clean washable type.
If filter is aluminum mesh it should be recoated
with filter c0at[ng spray.
FIG. 5 COUNTERFLOW FILTER
REPLACEMENT
CONDENSATE DISPOSAL
MonthlylAnnually
Your furnace has acondensate trap as part of the vent
system: The moisture in the flue gases will condense
and collect in the trap to go to an inside drain or be
pumped to a sewer line using a condensate pump.
]:he Condensate Trap and Condensate Neutralizer Car-
tridge (_{ used) in the drain line leading from the trap
will require some maintenance. Disassemble and clean
trap and cartridge prior to each heating season or if
drain line becomes plugged.
Inspect the drain fine and overflow line at least mon-
thly. If the Condensate Neutralizer Cartridge becomes
plugged the condensate will flow through the
overflow line. If this happens clean both cartridge and
trap.
TO CLEAN: Disconnect the drain line cartridge and
unscrew end cap from cartridge. Pour the neutralizer
out and thoroughly flush neutralizer and inside of car-
tridge with water. Pour neutralizer back into cartridge,
adding neutralizer if cartridge is less than ¾ full.
Unscrew trap from _/ent Connecting Tee and flush
throughly with water, use soap if necessary to clean,
DO NOT USE any kind of solvents. Make sure float
is reinstalled in trap, Ref. Fig. 7.
Reassemble and sea[ threaded connections with
silicone rubber (bathtub caulk)or pipe dope approved
for plastic pipe.
See repair parts section in the Furnace Technical Sup-
port Manual, to order replacement neutralizer.
Do not use Condensate for any reason as it is acidic.
5. Reinstall felt filter first. If filter is marked for air
flow direction make sure it's installed correctlY,
6, Replace blower compartment door making sure
that it's tightly closed.
7. Turn on electric power for the furnace.
FIG. 6 RECOMMENDED REMOTE FILTER SIZES
Nominal Toes
Air Conditioning
Nominal Air Flow
Cubic Feet per Minute
Up Thru 2Tons
800-900 CFM
2_'%ns
9OO-I 100 CFM
L3 Tone
1100-1300 CFM
3_'%.s
3300-I_00 CFM
4Tons
1500-1700 CFM
4_ Tons
1700-1900 CFM
5Tons
1900-2100 CFM
Recommended Filter Sizes
Sq, |_¢h Surface AtealNominal Size
Disposable Filters
432
20X25
480
20X30
576
14X25(2)
........672
16X25(2)
768
20×25121
864
20X25{2)
96O
20X30 12i
Cleanable Filzers
26O
15X20
288
14X25
346
t6X25
404
20X25
461
20X25
5_9
2_XZ5
576
24X25
Furnace Size
1000 X BTUH
40 50
75 (counter flow)
(onty]
40 5,0
75 1on
40 50
75 100
100 125
75 Eupflow on_y)
125
100 (upf!ow only)
125
125
10
FURNACE CONDITION AND
FLUE GAS PASSAGES/Monthly
A properly adjusted gas furnace.should not require
cleaning at frequent intervals, but it should be in-
spected regularly to ensure safe and efficient opera-
tion. A brief monthly inspection is recommended that
does not require disassembly, in addition you should
have the furnace inspected, and cleaned if required,
by aqualified service technician annually.
During the monthly inspection check the vent pipe and
fresh air intake (if installed), to be sure they are clear
and free of obstructions. Check vent pipe for evidence
of condensate leakage, tight joints, secure attachment
to furnace and sagging pipe.
Horizontal sections of pipe must slope upward 1/4"
per foot except sections between furnace and drain
trap when trap is not mounted directly on furnace.
Any horizontal section (max. 4" long) must slope down
a minimum of 1/4" per foot to trap. Vertical sections
to trap can be a maximum of 5 feet.
Check return air duct to make sure it is sealed to fur-
nace casing and that it is in good physical condition.
It must terminate outside the space containing the
furnace with no holes or inlets in furnace space.

Furnace Maintenance
FIG. 7 TYPICAL INSTALLATION (Cont.)
The floor or furnace base must be in good physical
condition. For Upflovv Furnace with a bottom return
the floor or base area around the furnace must form
a seat (no sagging, cracks defects etc.) to prevent air-
from being pulled in from furnace area, or any defect
area must be sealed between floor or base and
furnace.
Remove the front panel and use a flashlight to inspect
the visible part of the heat exchanger, burners and ig-
nitor. Check for loose soot and give particular atten-
tion to obvious deterioration from corrosion or other
sources. Check for any signs of condensate leakage
inside furnace cabinet.
tf soot or deterioration is found or if there is evidence
of condensate leakage inside furnace DO NOT
OPERATE FURNACE.
Calt a qualified service technician.
/ AIN BURNER 8L PILOT
FLAMESI! onthly
Allow furnace to run approximately 10 minutes then
inspect the main burner flames and pilot flame (ex-
cept furnaces with Hot Surface Ignition).
MAIN BURNER FLAMES should be stable, soft and
blue, (dust may cause orange tips or they may have
,wisps of yellow but they must not have solid yellow
tip_). They should extend directly upward from burner
without curling, floating or lifting off. They must not
touch the sides of the heat exchanger.
Con'tact a qualified service agency at once if an ab-
normal flame appearance should develop.
FIG. 8 MAIN BURNER FLAME
PILOT FLAME should surround 3/8"' to 1/2" of the
ignitor/sensor tip.
FIG. 9 PILOT FLAME
]]

.....SERVICE H
If your furnace fails to operate P'r6_edy_,, yalu.:may avoid i_ .convenience and the cost of a se£yicecall:by.cbeck-ing
the fotloWJng::,_eints' before you call for.service. .....................
NO HEAT OR
POSSIBLE CAUSE ':.:.,:_;.. •
.. " " <:s,_:
Thermostat not set correctl:y;
No electric power to furnase,
Filter is dirty. ..:
Gas, is •.shut _ff, ,:_:,' " '
Warm, air..r_g, isters ,clQse:d,or.,:blo_.ed.
Return grilles blocked.
WHAT TO DO :
Set •above room.temperature. Onhea_ingJcbofing Systems, turn
system switch to "Heat"; fan switch to "Auto" or "'On" (con-
tmu0us fan :operation). '
Cbeck fuse or circ..Uit breaker,.:Replace blown fuse, 'Reset breaker.
TuFn switch on. Be,sc_re blower access door _s se6ure,ty installed...
Clean fi.l:ter, i. . ,.:
Turn-gas valve on. "'. ., t
•,-Open _egisters..-Move rugs_, furniture, ether obstructions.. ...... :
Vent Pipe is dbstructed or Drainlines
on Condensate TraP. a-re _obstrL_otod.,_
causing float •..t.e,,r,ise,and. _blo¢..k,,#.#nt
pipe,
'Furnace has a pressure switch in the vent System which interrupts
:the elec:_.dca[ circdit: If the furnace is ,vented horizontally check the
outlet area to make sure it is not obstructed, Check cJrain lines and
Condensate Trap.
rURNACrE
Model NO. "::
FUrnace Size _Btuh) ',,
S:eria! No. •""::._:;;-,., .::!::.:•_'::
Where Purchased ,..
installer, .-.
_eale:r ............
RE ORD
_Da_:e
Date
Phone
Service History _..:.:'. "
_ociel No. Size. Set, a! _e. e&c. w_H be found on _he Furnace _at_ng Plan:e, see Page 5.

your
oIng
from
ing,
St ,
® If: _
• R_FERENCF-
SAVE THiS MANUAL FOR FUTURE _

SERVICE TECHNICIAN CHECK_
'When the furnace is being inspected for:c0ndition
and operation have the Service Technician check the
following items.
For additional information the Service Technician
can consult the installation instructions and ap-
plicable service manual for the furna'ce.
1. Check for adequate combustion air being sup-
plied to the furnace area and all air openings in-
to or from the furnace.
2. Check all flue gas passages including main and
pilot burners, heat exchanger, and vent pipe.
3. Check gas pipe and all connections inside and
leading to the furnace for leaks.
4. Check electrical wiring and connections.
5. Check supply and return air ducts for leakage,
blockage and connections to-furnace,
.Check circulating air blower wheel and motor,
clean and lubricate if required,
7. Perform: an Operational checkout on the furnace
tO :be sure safety: c0nt¢ols function and that fur-
nace oper_te_ _r0perly. ' ....
FREEZING TEMPERATURES
AND YOUR HOME
Your furnace is equipped with safety devices that may
keep it from operating if there are any abnormal con-
ditions affecting the furnace and L.P. models may not
operate if there is even a brief or slight interruption
in the electric power or gas supply,
tf your furnace remains shut down long enough dur-
ing freezing temperatures, for water pipes to freeze
it could result in serious water damage,
tf your home will be unattended during this time you
should take these precautions.
1. Shut the water off at the main inlet into your home
anddrain the water lines if possible,
2. Have someone check your home as often as
necessary for temperature conditions that could
cause water damage. Suggest they call a qualified
service agency if required,

COMBUSTION AIR/INDOOR ,HUMIDITY
(How. They Affect Your Safety and Comfort)
.! An energy efficient home or ahome using exhaus_
fans, fireplaces, clothes dryers, and gas appliances in-
creases this problem and your appliances could be
starving for air, which is unsafe.
This'_ay result in more and more air being drawn from
the house until fresh air is sucked in through an ap-
pliance flue or fireplace chimney. Carbon monoxide
can be the result.
J
Your home needs to breathe and the different
temperatures and humidity ranges in your home dur-
ing the year makes it necessary to be sensitive to air
requirements and potential ventilation problems.
Because of high energy costs for home heating,
new materials and methods are being used in con-
struction and remodeling. The improved construction
and additional insulation has made these homes much
tighter around windows and doors so that air leakage
is minimal. This may create aproblem in supplying
enough combustion and ventilation air for gas-fired or
other fuel burning appliances. Fresh air is needed for
combustion and ventilation of flue gases.
Carbon monoxide or "CO" is a colorless and odorless
gas produced when fuel is not burned completely or
when the flame does not receive sufficient oxygen.
CARBON MONOXIDE CAN RESULT IN
ASPHYXIATION.
Be aware of these air starvation signalsi
1. Headaches-Nausea-Dizziness
2. Excessive humidity-Heavily frosted win-
dows or a moist "clammy" feeling in the
home.
3. Smoke from the fireplace won't draw up
the chimney.
4. Flue gases ,won't draw up the appliance
flue pipe.
1. How do I know if my furnace or other appliances are receiving enough
air for proper combustion and ventilation of flue gases?
Use the following checkout procedure to determine
if the air leakage into your home is adequate tosupp-
tyth e needs of your appliances and fireplace. If you
are uncertain about your ability to perform these
checks contact your installing dealer or place of
purchase.
5. Check for draft hood spillage at each appliance.
(Hold a lighted_matCh 2" from draft opening as :
shown for the:typical gas water heaterii :
FIG. 1 CHECK :FOR DRAFT HOOD SPILLAGE
A.
1.
Make the inspection as follows:
Close all doors and windows. If you have a
fireplace, start a fire and wait until flames are bur-
ing vigorously.
2. Turn on all exhausting devices, such as: kitchen
and bathroom exhaust fans - dryers (gas or
electric)
3. Turn on all vented gas appliances, such as: heating
equipment (includes any room heaters) water
heaters.
4. Wait ten (10) minutes for drafts to stabilize.
B. No Spillage -
if match flame pulls toward draft hood, this in-
dicates sufficient infiltration air. Return exhausting
devices and appliances to the condition you found
them.

}.- -: :>:h _ :i:/;,:'=; _ ':
"I:!S;I;!, _Lii_:i;_:_:_i_:_ :_'
Combustion Air iAdoor Humidity (Cont.)
C. Drafthood Spillage - _ _::_:
If there is spillage at a draft hood - (rfi_ch goes
out or flame wavers away from draft'Jiood):
1. Check for plugged flue connectors and chimneys.
Check and repair stoppage and test again.
2. if you have a fireplace, open awindow or door
near the fireplace and then check for spillage.
a. If spillage stops, do not use the fireplace until
you can supply fresh air by a permanent duct.
3. If you have kitchen and bathroom exhaust fans
turn them off and check for spillage.
a. If spillage stops, do not use exhaust fans until
you can supply fresh air by apermanent duct.
Circuit breakers for fans should be turned off.
4. Spillage means air starvation and a fresh air duct
or air intakes must be installed to provide air
directly to the furnace or other gas appliance.
These must comply with local and state building
codes or in their absence with the National Fuel
Gas Code NFPA 54/ANSI Z223.1, current edition.
2. What is Relative Humidity and how do I know if it is tOo high or low?
Relative humidity is the amount of water vapor in the air
relative to the amount the air can hold at the same tempera-
ture. Example: At 40% relative humidity, the air can hold
60% more moisture before it is saturated.
The colder the air, the less moisture it can hold. As air is
warmed, its ability to hold moisture is increased. Example;
A winter day, outdoor temperature 10°F, and relative
humidity of 70%. If that air enters ahome and is warmed
to 72°F the relative humidity will drop to 6% (very dry) if
no more moisture is added.
Relative humidity is important to your health and home as
proper humidification helps cut down on incidences of
respiratory illness and helps keep air cleaner and fresher.
HAS YOUR FURNACE BEEN REPLACED?
This furnace is very efficient and has amuch smaller vent
(flue) pipe with a brower in the venting system.
The smalMr vent and blower increases the efficiency of the
furnace but they will also decrease the amount of natural
air infiltration into the house. This is because less air will
escape up the vent system during the off cycle so less cold
dry air will enter the house by it_fllteration, This in conjunc-
tion with other items may cause the humidity to raise to
uncomfortable levels. This condition can usually be elimi-
nated by minor changes in everyday routines, see "If
Humidity Is Too High".
VISUAL METHODS OF GAUGING INDOOR
HUMIDITY:
• Frequent fogging or excessive condensation on inside
windows indicates the indoor humidity level is too high
for outdoor weather conditions. Damage to the buiiding
may result if the condition persists. (Condensation on in-
side of storm windows indicates loose inside windows.
Adding weatherstripping to tighten inside windows
usually corrects this problem.)
A good relative humidity is one just high enough to barely
start condensation along the lower edges or tower corners
of the windows. More than that can be damaging°
IF HUMIDITY IS TOOHiGH,I. '_!'"
Condensation occurs when Warm; moist air Cdntacts a_c6o!
surface (window or outside wall, for,example), add drops of
water or acoating of frost form. The c05densation problem
increases as the outside temperature decreases.
A high humidity level usually result sfr0i:n bathing or cook-
ing, etc. Suggestions for correcting this problem:
1. Turn down or discontinue use of humidifier.
2, Use range and bathroom exhaust fans while cooking and
bathing or open a door or window for afew minutes to
bring in cool dryer air.
3. Cook with pans covered.
4. Take shorter baths or showers with cooler water.
5. Install afresh air intake duct. Cold, dry air brought in
from outside to the furnace area lowers the indoor
humidity_level.
6. ffthe above measures do not correctthe problem, have
appliances checked. A rmalfunctioning appliance can
contribute water vapor to the house,
7. -if the above items do not correct the problem consult
a heating contractor about adding aheat recovery ven-
tilator or afr to air heat exchanger.
RECOMMENDED INDOOR HUMIDITY:
Use the following table as a guide. It shows the recommend-
ed maximum indoor humidity in relationship to the outdoor
temperature.
TEMPERATURE HUMIDITY
•Drop three ice cubes into a glass of water and stir. If,
within three minutes, moisture does not form on the
glass, the air is too dry and a humidifier would be
beneficial. (Do not perform this test in the kitchen, as
cooking vapors may produce inaccurate results.)
+20°E and above 35%
+10"F 30%
0°F 25%
-10°F 20%
-20°F 15%
4

YOUR FURNACE
Condensing furnaces have ahigher efficiency rating
than conventional gas furnaces, but are basically the
same in design and operation, The major difference
is the addition of a secondary heat exchanger which
captures heat that would normally go out the furnace
vent pipe,
By capturing this heat the flue gases are cooled to a
point where most of the vapor' (mainly water) con-
denses out and must be drained away, Because the
gases are cooled down plastic pipe is used for the vent
pipe in place Of metal.
The following paragraphs and Illustration wil! help you
to understand the main parts of your furnace and how
they operate.
DOOR INTERLOCK SWITCH
All of the electrical power for the furnace goes through
the Door Interlock Switch and the furnace will not
operate if the Blower Door is not properly in place.
ELECTRICAL
JUNCTION/CONTROL BOX
System Relay
Fan Relay
Transformer-1 15V to
DOOR INTERLOCK SWITCH
EXHAUST TEMPERATURE
LIMIT SWITCH
COMBUSTION AIR
BLOWER
FAN/LIMIT CONTROL
ELECTRONIC SPARK
MODULE
FLAME ROLLOUT
SPARK IGNITOR/PILOT BURNER
OR HOT SURFACE IGNITOR
AND MAIN BURNERS INFORMATION LABELS
Safety & Service Clearances
Lighting Instructions (inside or on
Back Side of Door Panel)
Rating Plate FIG. 2
TYPICAL COUNTERFLOW
CIRCULATING AIR BLOWER
AIR PROVING SWITCH
SECONDARY HEAT EXCHANGER
PRIMARY HEAT EXCHANGER
White Rodgers Valve - 36 E Series
Hot Surface Ignition
@
Honeywell Valve - 8204 Series
Spark to Pilot Ignition

Your Furnace (Cont.)
AIR PROVING SWITCH
LIMIT CONTROL
IGNITOR/SENSOR
COMBUSTION AIR BLOWER
EXHAUST TEMPERATURE
UMIT SWITCH
ELECTRICAL JUNCTION
BOX
DOOR INTERLOCK
ELECTRICAL CONTROL BOX
SYSTEM RELAY
FAN RELAY
TRANSFORMER-115V - 24V.
White Rodgers Valve 3'6 i i
- E Series
Hot Surface ignition
Honeywell Valve _8204 Series
Spark to Pilot ignition
PRIMARY HEAT EXCHANGER
GAS VALVE
FLAME ROLLOUT SENSOR
SECONDARY HEAT
EXCHANGER'
FAN CONTROL
ELECTRONIC SPARK
MODULE
CIRCULATING AIR BLOWER
FILTER (SHOWN IN BOTTOM)
MAY BE MOUNTED IN SIDE
THE OSTAT FIG, 3
TYPICAL UPFLOW
See separate description under "Thermostat". As the
temperature in your home drops the thermostat closes
and completes a tow voltage (24V) control circuit to
the System Relay inside the control I_ox. This relay
closes and provides power to the Electronic Ignition
Module, and Combustion Air Blower. The thermostat
also completes a circuit to an internal heater inside
the Fan/Limit Control. This allows more precise Fan
"ON" control to help maintain comfortable
temperatures in your home.
ELECTRONIC SPARK
MODULE/GAS VALVE
When the thermostat calls for heat it completes a Low
voltage (24V) circuit to the electronic ignition module.
The module either starts an electric spark or activates
a hot surface ignitor to ignite the gas as the gas valve
opens letting gas through to pilot or main burner.
When the flame is firmly established the module will
shut off. For safety it will automatically restart if the
flame is interrupted. !f there is an abnormal function,
the gas valve is designed to automatically shut off the
gas.
COMBUSTION AIR BLOV#ER
The System Relay closes to start the Combustion Air
Blower which exhausts the vent gases out through
the vent pipe. The blower creates a pressure differen-
tial inside the furnace which provides the right amount
of induced draft (air) to properly control combustion
for maximum efficiency. This part of the system pro-
vides several safety features as the electrical circuit
for the Electronic Ignition Module/Gas Valve must go
through a Flame Rol! Out Sensor, Air Proving Switch,
Exhaust Temperature Limit Switch and the
temperature limit portion of the Fan/Limit Control.
If the right amount of air is not going through the fur-
nace or if temperatures are too hot the electrical cir-
cu=t to the Electronic Ignition Module/Gas Valve will
be interrupted.
6

Your Furnace (Cont.)
CIRCULATING AIR BLOWER
The blower to circulate room air through the furnace
starts as soon as the internal.heater in the Fan/Limit
control causes the fan switch portion to close com-
pleting the electrical circuit.
It shuts off when the Fan/Limit Control opens the elec-
trical circuit. This means the blower comes on approx-
imately 30 seconds after the fu'rnace first starts and
it continues to run unti] the furnace cools down. This
helps to achieve the maximum comfort and efficien-
cy. from your furnace.
FAN RELAY
This relay provides electric power to the Circulating
Air Blower for continuous blower operation (Ther-
mostat Fan Switch set to "FAN ON") and for the
blower to run if central .air conditioning is installed.
FAN/LIMIT CONTROL
The Fan/Limit Contro! provides power to the Cir-
culating Air Blower to keep it on, until the furnace
cools down. The limit portion provides safety because
it will open the low voltage control circuit, shutting
the furnace down if it gets too hot.
The fan off setting can be adjusted if the fan remains
on long enough that cool drafts are felt in the room
after the furnace shuts off. Contact a Qualified Ser-
vice Technician.
DRAIN TRAP ASSEMBLY
The drain trap has a float in it, that will cause the fur-
nace to shut down if the drain lines become
obstructed. If this happens the trap and lines must be
taken apart and cleaned. See "Condensate Disposal'"
page 10.
Thermostat
Your furnace will not operate properly without agood
quality, correctly installed thermostat. The thermostat
location is very important as it must be sensing
average room temperatures. It must not be exposed
to hot or cold drafts or hot or cold spots on the wall,
such as outside walls or awalt with pipes inside or
openings into attic.
There are many types and styles of thermostats but
the operation is usually similar. BE SURE TO BECOME
FAMILIAR WITH YOUR THERMOSTAT, The simplest
type of thermostat only starts and stops the furnace
to maintain the proper room temperature. The most
widely used types will control both heating and cool-
ing functions and will have a Fan Switch with Auto
and ON settings. On Auto, the Circulating Air Blower
will cycle on/off with the furnace but if, switched to
ON it will run constantly whether or not the furnace
is on.
In addition there are thermostats that automatically
switch from Heating to Cooling and with night set-
backs. The night set-back, or multiple set-back type,
will lower the temperature at night or during the day
when no one is at home.
HEATING:
Posftion the Thermostat System Switch on HEAT, Set
the Fan Switch to AUTO for the blower to cycle
ON/OFF. Sefect desired temperature setting and fur-
nace will automatically start up and shut off as re-
quired to maintain that setting, Fan Switch may be
positioned to ON for continuous air circulation only
if that position maintains the same or a higher blower
speed so you have the same or greater- airflow.
CAUTION
Continuous Fan ON at too slow of a blower speed may
cause improper furnace operation and possible
damage to the heat exchanger,
HEATING ANTICIPATOR:
For more precise comfort control your thermostat may
have an adjustable Heat Anticipator. (Some are not ad-
justable). For most homes the anticipator should be
set on the value listed in the Tech Data Sheet which
is found in the Furnace Technical Support Manual.
If your furnace cycles ON/OFF with very short-ON in-
tervals or _f the OFF cycle is so long that room
temperatures become uncomfortable the anticipator
setting may need to be adjusted.
To Adjust:
Remove thermostat cover and locate anticipator,
Check ,the setting. !f not on.thesetting recommen_
ed for your furnace, moye the lever to the proper set-'
ting and try it.for a day or two,
To lengthen burner-on time move' the indicator
towards "Longer"_ To decrease burner-on time move
in opposite direction,
ira= ii i ii
NOTE :
To accurately determine the effect do not adjust
more than half ascale marking at a time and
I
iI allow a day between adjustments.
I ii iiiiiiii II II III I ' iiiiiiiiiiiiii
COOLING:
For cooling simply position the system switch to
COOL Instead of HEAT and thermostat will function
in the same manner to control cooling.
7

Operating Your Furnace
Keep the blower access door and upper access panel
in place except for inspection or maintenance. An
automatic switch prevents furnace operation if the
blower door is not in place.
Before starting your furnace be sure you read and
understand all of the procedures in this manual. Check
to make sure the furnace filter is clean and correctly
installed.
STARTING THE FURNACE
See page 5 or 6 for location and illustration of gas
valve.
1. Turn the thermostat to its lowest temperature
setting or to OFF if equipped with a System
Select Switch.
2. Turn Manual Shutoff Valve, in the gas line, to
OFF position, should be a right angle or 90 ° to
gas line.
3. Turn OFF electric power to furnace at disconnect
switch or circuit breaker.
4. Remove furnace access panel, exposing gas con-
trois and burner compartment.
5. Locate gas valve and identify settings.
The valve is marked with ON -- OFF positions.
6. Turn the knob all the way to OFF. Make sure it
has been in OFF for at least 5 minutes before
proceedint].
7. Turn the contrQ! knob to ON (Depress knob to
turn on some Honeywell valves).
Replace access panels and doors.
Turn ON electric power for furnace,
Open the,-Manual Shutoff Valve in the gas4ine,
: ,, ..... .... ,, • , ,.. -
Set therm0stat:to desired temperature-and
System Select Switch to HEAT if equipped.
The furnace witI begin sparkingto ignite the pilot flame
or the hot surface ignitor will heat up to ignite the gas.
When the system verifies a steady flame the ignition
system will shut off.
.
9.
10.
11.
WIHH HOT SURFACE
IGNITION SYSTEM
Furnace will make several attempts to lite before go-
ing into lockout. Each attempt requires alonger time
with the total cycle taking approximately 8-10
minutes.
If air remaining in the tines on a new installation
prevents the furnace from lighting ONE additional cy-
cle may'be tried, tf furnace does not light, turn the
thermostat to its lowest setting. Wait one minute,
then turn it back up abovethe temperature shown on
the thermometer. This starts the ignition cycle over
again. DO NOT REPEAT MORE THAN ONCE. If fur-
nace will not light, call a qualified Service Agency.
TURNING OFF THE FURNACE
1. Set the thermostat to the lowest setting or set
System Select Switch to OFF if equipped.
,_Shouidoverheating occur or the gas supply fail to
shut off, shut off the manual gas valve to the fur-
nace before shutting off the electrical supply.
EXTENDED SHUTDOWN
1. Set thermostat to lowest setting or set System
Select Switch to OFF if equipped.
2. Turn Manual Shutoff Valve to off position, right
angle or 90 Dto gas line.
3. Turn electric power off. (May be left "ON" for
set-back or chronograph type thermostat with
batteries, provided thermostat has a system
select switch to place in the "OFF" position.)
4. Turn the gas valve control knob to "OFF".
Winter Shutdown
tf there is the possibility of freezing temperatures,
remove the Condensate drain trap and empty to pre. *,
vent freezing. ........ ....... ....
L P Model Furnaces
With Spark to Pilot Ignition (System Retries)
The ignition system will spark to light the pilot for 90
seconds. If the pilot does not light within 90 seconds
the system will shut off for 5 minutes and then it will
try again for 90 seconds. It will continue to cycle un-
til the pilot lights, (90 seconds ON/5 minutes OFF).
If the unit does not start after 3 tries or approximate-
ly 20 minutes, shut ,the unit off at the thermostat and
call a qualified Service Agency. ..