Unitary products group PxDU series User manual

OWNER’S MANUAL
TWO STAGE
MID - EFFICIENCY
GAS-FIRED FURNACES
UPFLOW/HORIZONTAL MODELS: P*DU / G8D-UH / L8D-UH
DOWNFLOW MODELS: P*DD / G8D-DN
035-14396-000 REV B (4/00)
CONTENTS
HOW YOUR GAS FURNACE WORKS. . . . 2
KEEP THE FURNACE AREA CLEAR . . . . .2
START-UP AND SHUTDOWN GENERAL
INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . .2
FOR YOUR SAFETY, READ BEFORE
OPERATING: . . . . . . . . . . . . . . . . . . . . . . . .2
WHAT TO DO IF YOU SMELL GAS: . . . . . .2
LIGHTING INSTRUCTIONS . . . . . . . . . . . . .2
SHUTDOWN INSTRUCTIONS . . . . . . . . . . .3
YOUR FURNACE'S FILTER -
WHAT IT DOES . . . . . . . . . . . . . . . . . . . . . . 3
FREQUENCY OF CHECKING FILTERS . . .3
LOCATING / REMOVING FILTERS . . . . . . .3
HOW TO CLEAN YOUR
FURNACE'S FILTER . . . . . . . . . . . . . . . . . .4
MOTOR LUBRICATION . . . . . . . . . . . . . . . .4
INSTALLATION & MAINTENANCE
INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . .4
WARNING: If the information in this manual is not
followed exactl
y
, a fire or ex
p
losion ma
y
result causin
g
p
ro
p
ert
y
dama
g
e,
p
ersonal in
j
ur
y
or loss of life.
- Do not store or use
g
asoline or other flammable va
p
ors
and li
q
uids in the vicinit
y
of this or an
y
other a
pp
liance.
- WHAT TO DO IF YOU SMELL GAS
•Do not tr
y
to li
g
ht an
y
a
pp
liance.
•Do not touch an
y
electrical switch; do not use an
y
p
hone in
y
our buildin
g
.
•Immediatel
y
call
y
our
g
as su
pp
lier from a nei
g
hbor’s
p
hone. Follow the
g
as su
pp
lier’s instructions.
•If
y
ou cannot reach
y
our
g
as su
pp
lier, call the fire
de
p
artment.
- Installation and service must be
p
erformed b
y
a
q
uali-
fied installer, service a
g
enc
y
or the
g
as su
pp
lier.

035-14396-000 REV B (4/00)
2Unitary Products Group
HOW YOUR GAS FURNACE WORKS
Your furnace is a very easy appliance to
take for granted. Season after season, it sits
there in your home, keeping you warm and
comfortable. For this reason, you may never
have given much thought to the way your
furnace operates. In order to get the safest
and most efficient operation from your fur-
nace, though, you should understand how
your furnace does its job.
When you set your thermostat to provide
more heat in your home, you are starting the
heating cycle of the furnace. First, the
inducer motor starts to purge the heat
exchanger of any remaining gasses. Next,
the hot surface ignitor glows and after a
warm-up period the gas valve opens and
ignition occurs. A short time later the blower
starts and distributes the warm air through-
out the home. When the temperature set on
your thermostat is reached, the gas valve
closes, the main burners are turned off, and
the blower continues to run until the remain-
ing warm air in the system is distributed.
When the blower stops, the heating cycle
has ended.
KEEP THE FURNACE AREA CLEAR
NEVER . . . use the area around your fur-
nace as a storage area for items which
could block the normal flow of air. This flow
of air is required for ventilation of the various
furnace components.
NEVER. . store flammable materials of
any kind near your furnace. Gasoline, sol-
vents, and other volatile liquids should be
stored only in approved containers outside
your home. These materials vaporize easily
and are extremely dangerous.
NEVER . . .store cleaning materials near
your furnace. Materials such as bleaches,
detergents, powdered cleansers, etc., can
cause corrosion of the heat exchangers.
START-UP AND SHUTDOWN
GENERAL INSTRUCTIONS
Read and follow these procedures CARE-
FULLY and COMPLETELY.
Before attempting to start your furnace,
always do the following things FIRST:
• Turn the thermostat OFF.
• Open windows or make other provi-
sions to ventilate the area around the
furnace.
• If the blower is running, wait until it
shuts off automatically.
• Turn off all electrical power to the fur-
nace.
• Make sure all metal surfaces of the fur-
nace have cooled to room temperature
before beginning.
FOR YOUR SAFETY, READ BEFORE
OPERATING:
A. This appliance does not have a pilot. It
is equipped with an ignition device
which automatically lights the burners.
Do not try to light the burners by hand.
B. BEFORE OPERATING, smell all
around the appliance area for gas. Be
sure to smell next to the floor because
some gas is heavier than air and will
settle on the floor.
WHAT TO DO IF YOU SMELL GAS:
• Do not try to light any appliance.
• Do not touch any electrical switch; do
not use any phone in your building.
• Extinguish any open flame
• Immediately call your gas supplier from
a neighbor's phone. Follow the gas
supplier's instructions.
• If you cannot reach your gas supplier,
call the fire department.
• Use only your hand to turn the gas con-
trol knob. Never use tools. If the knob
will not turn by hand, don't try to repair it.
Call a qualified service technician. Force
or attempted repair may result in a fire or
explosion.
LIGHTING INSTRUCTIONS
1. STOP! Read all preceding safety
information.
2. Set the thermostat to lowest setting.
3. Turn off all electrical power to the
appliance.
4. This furnace is equipped with an
ignition device which automatically
lights the burners. Do not try to light
the burners by hand.
5. Remove the control access panel.
6. Turn gas control switch to "OFF".
Do not block or obstruct air openin
g
s:
1. On the furnace.
2. Air openings communicating with the
air in which the furnace is installed.
3. The spacings around the furnace.
Insulatin
g
materials ma
y
be flammable.
When a furnace is installed in an attic or
other insulated space, or if insulation is
added, examine the furnace area to
ensure that the furnace is kept clear and
free of insulation.
If
y
ou do not follow these instructions
exactl
y
, a fire or explosion ma
y
result,
causin
g
propert
y
dama
g
e, personal
injur
y
or loss of life.
Do not use this furnace if an
y
part has
been under water. Immediatel
y
call a qual-
ified service technician to inspect the fur-
nace and to replace an
y
part of the control
s
y
stem and an
y
g
as control which has
been underwater.
Congratulations . . .
On your purchase of one of the most versatile furnaces available in the industry today. This compact, energy-efficient furnace
has been precision designed, manufactured of high-quality materials and has passed many rigorous inspections and tests to
ensure many years of satisfactory service. This booklet is meant to increase your understanding of your unit, tell you how to
operate it efficiently and how to obtain the greatest measure of comfort at the lowest operating expense. Please read this book-
let thoroughly. We appreciate your interest in our product and your decision to purchase our furnace. Enjoy your comfort.

035-14396-000 REV B (4/00)
Unitary Products Group 3
7. Wait five (5) minutes to clear out any
gas. If you then smell gas, STOP!
Follow step B in the preceding safety
information. If you don't smell gas,
go to the next step.
8. Turn gas control switch to "ON". Do
not force.
9. Replace control access panel.
10.Turn on all electrical power to the
appliance.
11.Set thermostat to the desired set-
ting.
12.The unit will go through a 17-second
igniter warm-up period. Then if the
unit does not light within 7 seconds,
the unit will go through two additional
cycles before locking out.
13.If the furnace will not operate, follow
the instructions "To Turn OFF Gas
To Furnace" and call your service
technician or gas supplier.
SHUTDOWN INSTRUCTIONS
To Turn OFF Gas To Furnace
1. Set thermostat to the lowest setting.
2. Turn off all electrical power to the
furnace if service is to be performed.
3. Remove the control access panel.
4. Turn the knob on the gas control
clockwise to OFF.
5. Replace the control access panel.
YOUR FURNACE'S FILTER - WHAT
IT DOES
The filter in your furnace takes the lint and
dust out of the air that passes through it.
This keeps dirt particles from getting into the
moving parts of the furnace, where they
could cause serious damage. It also keeps
the dirt from circulating through your home.
As the filter continues to collect these parti-
cles, it becomes clogged and no longer
allows enough air to circulate through the
furnace. If this happens, the heat exchang-
ers and blower motor could overheat; a
potentially dangerous situation. It is very
important to keep the air filter clean! Never
operate your furnace without a suitable air
filter.
FREQUENCY OF CHECKING
FILTERS
Clean your furnace's filter at least every
three months. If you need to replace a filter,
check the filter chart to be sure you install
the right size and type of filter for your fur-
nace.
If your home is new, you should check the
filter every week for the first four weeks after
you begin to use the furnace, and then at
least every three weeks after that, especially
if the system runs constantly.
NOTE: Some installations ma
y
have more
than one filter.
LOCATING / REMOVING FILTERS
Upflow Furnaces
Most upflow furnaces have their filters
located on the side or bottom of the furnace
in a filter frame.
If your furnace has this type return filter
frame, remove the door by pulling on it.
Slide the filter out of its channel. To replace
after cleaning, slide filter into place and
snap the door on the end of the filter rack.
Some installations may have filters located
in the blower compartment. Check with the
installer for your filter location.
To check filters located in the blower com-
partment, remove the upper furnace door by
lifting up. Pull out bottom of door and lower
from furnace. Remove the blower compart-
ment panel by lifting up.
NOTE:The sprin
g
-loaded safet
y
cutoff
switch, mounted under the blower deck will
automaticall
y
cut off the electrical power
suppl
y
to the furnace when the blower panel
is removed
.
To remove bottom mounted filter(s) on all
furnaces, push the looped end of the filter
retainer to the side and then lift up. Reverse
the procedure to reinstall filters.
Downflow Furnaces
Should overheatin
g
occur, or the
g
as sup-
pl
y
fail to shut off, shut off the main man-
ual
g
as valve to the furnace before
shuttin
g
off the electrical suppl
y
.
T
y
pical Gas Pipin
g
GAS VALVE
DROPLEG
GROUND JOINT UNION
MAY BE INSTALLED
INSIDEOROUTSIDEUNIT
TO GAS
SUP
PLY
T
O GAS
S
UPPLY
EXTERNAL MANUAL
SHUTOFFVALVE
Gas Valve - White-Rod
g
ers 36E96
When replacin
g
filters DO NOT use a t
y
pe
with excessivel
y
hi
g
h pressure drop.
Some hi
g
h efficienc
y
filters available will
cause the furnace to operate improperl
y
and could result in a safet
y
hazard.
LOW FIRE
REGULATOR
ADJUSTMENT
SEAL SCREW
HIGH FIRE
REGULATOR
ADJUSTMENT
SEAL SCREW
Upflow Furnace Bottom Mount Filter
Retainer
UPFLOW FURNACE WITH
EXTERNAL FILTER RACK

Subject to chan
g
e without notice. Printed in U.S.A. 035-14396-000 REV B (4/00)
Copyri
g
ht © by Unitary Products Group 2000. All ri
g
hts reserved. Supersedes: 035-14396-000 REV A (4/00)
Unitary 5005 Norman
Products York OK
Group Drive 73069
035-14396-000 REV B (4/00)
The filters in your downflow furnace are
located in the plenum or ductwork above the
furnace.To check the filters, turn off the elec-
trical supply to the furnace.
Remove the access cover in the return air
duct above furnace and slide the filter(s) out
of the filter channel. You may need to tilt the
filter in order to clear the vent pipe.
NOTE:The sprin
g
-loaded safet
y
cutoff
switch, mounted to the blower deck will
automaticall
y
cut off the electrical suppl
y
to
the furnace when the blower access door is
removed.
Horizontal Furnaces
Most horizontal furnaces have their filters
located in a filter grille(s) so that it may be
easily changed without gaining access to
the attic or crawl space.
Some installations may have a filter rack
near the furnace. With this type of acces-
sory, unsnap the filter rack door and pull.
The filter is attached to the door and will
slide out. If you are unsure where the fur-
nace filter is installed, check with the
installer.
HOW TO CLEAN YOUR FURNACE'S
FILTER
High-velocity filters may be cleaned with a
vacuum cleaner or washed with a garden
hose. Be sure to shake off excess water
before re-installing the filter.
MOTOR LUBRICATION
The motors in these furnaces are perma-
nently lubricated, and require no periodic oil-
ing.
INSTALLATION & MAINTENANCE
INSTRUCTIONS
The manufacturer strongly recommends
regular periodic preventative maintenance
on this equipment.
The person most familiar with the equipment
in your system is your dealer. The dealer
can ensure your maintenance program
meets the conditions of the warranty, maxi-
mize the efficiency of the equipment, and
service your unit within the mandated guide-
lines with regard to unlawful discharge of
refrigerants.
The inspection should include heating ele-
ment, vent piping, to see that they are clear
and free of obstructions and without holes or
corrosion. Make sure the horizontal run of
the vent system slopes upward and all of the
connections are secure.
Make sure the return air duct connections
are physically sound and sealed to the fur-
nace casing. Make sure no sagging, cracks,
gaps, etc. exist around the base of the fur-
nace.
Routine periodic maintenance checks
should be done on your furnace at least
every time you check the filters. Proper
burner flame appearance is shown in fig-
ure..
Remove the front panels and turn the knob
on the gas control to the OFF position.
Check the following items:
•Check for dust and lint on the sensor
and main burners.
•Check the vent pipe and chimney for
blockage, corrosion or leakage or any
obstructions.
•Check all components to be sure they
are in good condition and that there
are no obvious signs of deterioration.
If all components appear to be in good oper-
ating condition, turn the gas control to the
ON position. Replace the front panels.
Restore gas and power supplies to the fur-
nace, and set thermostat to the desired tem-
perature.If, during your inspection of your
furnace, you find any of the following condi-
tions, do not operate the furnace:
•Excessive amounts of dust and lint on
components.
•Damaged or deteriorated components
or surfaces.
•Leaks or blockage in the vent pipe pas-
sages.
Call a certified service contractor to check
your furnace, or for more information if you
have questions about the operation of your
furnace.
Downflow Furnace - T
y
pical Filter
Location
Horizontal Furnace - T
y
pical Filter
Location
VENT PIPE
FURNACE
RETURN
AIR
DUCT
ACCESS
PANEL
FURNACE RETURN AIR DUCT
Before proceedin
g
, be sure the area is
well ventilated. Turn the thermostat OFF.
If the blower is runnin
g
, wait until it stops
automaticall
y
. Turn OFF the
g
as and
electrical power supplies to the furnace.
Check all metal parts and surfaces to be
sure the
y
have cooled to room tempera-
ture before
y
ou be
g
in.
In order to ensure safe, reliable operation
and long product life, it is recommended
that the entire heating system be
inspected annually by a qualified service
person.
Proper Burner Flame Appearance
SUGGESTED HIGH VELOCITY FILTER SIZES
UP/HZ
CABINET SIZES
FILTER SIZE
SIDE BOTTOM
(A) 14 1/2 16 x 26 14 x 26
(B) 17 1/2 16 x 26 16 x 26
(C) 21 (2) 16 x 26 20 x 26
(D) 24 1/2 (2) 16 x 26 24 x 26
Downflow
Cabinet Sizes Filter Size
All Models (2) 14 x 20
Blue cone portion of flame should enter
heat exchanger tube