Dynavent DNV25NB Quick start guide

Save this manual for future reference.
DYNAVENT

WINDOW WALL FURNACE
DIRECT-VENT NATURAL GAS HEATER
OWNER’S OPERATION AND INSTALLATION MANUAL
SOLIDSTATE IGNITION
50 60 70 80 90
50 60 70 80 90
DNV25NB
DNV40NB
25,000 and 40,000 BTU/Hr“B”Model Furnaces
FOR YOUR SAFETY
Donotstoreorusegasolineorotherflammablevapors
andliquidsinthevicinityofthisoranyotherappliance.
FOR YOUR SAFETY
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.
• Immediatelycallyourgassupplierfromaneighbor’s
phone. Follow the gas supplier’s instructions.
• If you cannot reach your gas supplier, call the fire
department.
WARNING:Improperin-
stallation, adjustment,
alteration, service, or
maintenancecancause
injury or property dam-
age.Refertothismanual
for correct installation
and operational proce-
dures.Forassistanceor
additional information
consult a qualified in-
staller, service agency,
or the gas supplier.
WARNING:Iftheinformationintheseinstructionsisnot
followedexactly,afireorexplosionmayresultcausing
property damage, personal injury, or loss of life.
— Installation and ser-
vicemustbeperformed
by a qualified installer,
service agency, or the
gas supplier.
* Aftermarket: Completion of sale, not for purpose of resale, from the manufacturer
Thisappliancemaybeinstalledinanaftermarket*,permanentlylocated,manufac-
tured (mobile) home, where not prohibited by local codes.
Thisapplianceisonlyforusewiththetypeofgasindicatedontheratingplate.This
appliance is not convertible for use with other gases.

2
201835
DIRECT-VENT NATURAL GAS HEATER
DYNAVENT
®
gases will result. Carbon monoxide
poisoning from backed-up flue gases
could occur. The State of California
lists carbon monoxide as a reproduc-
tive toxin under Proposition 65.
7. Never install the furnace
• in a recreational vehicle
• in an alcove
• on an inside wall
• as a fireplace insert
• in high traffic areas
• in windy or drafty areas
• behind a door or where an open door
would block normal air flow
8. Provide the following minimum fur-
nace clearances from furnace front
cover to combustibles (as viewed from
the front of furnace):
Below Front Cover: 6 inches
Adjoining Wall: 12 inches
Above Front Cover: 12 inches
Front: 8 feet
9. Do not obstruct the flow of combus-
tion and ventilation air in any way. Pro-
vide adequate clearances around air
openings into the combustion chamber
alongwith adequate accessibility clear-
anceforservicingandproperoperation.
10. Providethefollowingminimum furnace
clearancesfromfurnacecabinet (portion
of cabinet extending into outside air, as
viewed from the rear of furnace):
Cabinet Back: 36 inches
Cabinet Sides: 6 inches
Cabinet Bottom: Must be high enough
off the ground to prevent snow, water,
leaves,or any other objects from block-
ing cabinet vents.
11. Always follow lighting instructions.
Never attempt to light burner with a
match or butane torch.
12. Do not run furnace
• where flammable liquids or vapors
are used or stored
• under dusty conditions
13. Do not use furnaceasacooking device.
14. Do not alter furnaceoritscontrols.Any
change may create a safety hazard.
15. Do not use furnace if any part has been
under water. Immediately call a quali-
fied service person to inspect the fur-
nace and to replace any part of the con-
trol system and any gas control which
has been under water.
Carbon Monoxide Poisoning: Early signs of
carbon monoxide poisoning resemble the flu,
with headaches, dizziness, and/or nausea. If
you have these signs, the furnace may not be
workingproperly.Getfreshairatonce!Have
furnace serviced. Some people are more af-
fected by carbon monoxide than others. These
include pregnant women, people with heart or
lung disease or anemia, those under the influ-
ence of alcohol, and those at high altitudes.
NaturalGas:Naturalgasisodorless.Anodor-
makingagentisaddedtonaturalgas.Theodor
helps you detect a natural gas leak. However,
the odor added to natural gas can fade. Natural
gasmaybepresenteventhoughnoodorexists.
Makecertainyou read andunderstandallwarn-
ings. Keep this manual for reference. It is your
guidetosafeandproperoperationofthisfurnace.
1. A qualified service person must install
furnace.
2. This appliance is only for use with the
typeofgasindicated on the rating plate.
Thisapplianceisnotconvertibleforuse
with other gases.
3. Use only natural gas. Do not convert
furnace to use different fuel type.
4. If you smell gas
• Shut off gas supply.
• Do not try to light any appliance.
• Donottouchanyelectricalswitch;do
not use any phone in your building.
• Immediately call your gas supplier
from a neighbor’s phone. Follow the
gas supplier’s instructions.
• Ifyoucannotreachyourgassupplier,
call the fire department.
5. Do not block the flow of combustion
air (outside air) or heated air (room air)
to the furnace.
6. This furnace must have fresh air for
proper operation. If not, poor fuel com-
bustion and improper venting of flue
SAFETY
INFORMATION
WARNINGS
IMPORTANT: Read this owner’s
manual carefully and completely
beforetryingtoassemble,operate,
or service this furnace. Improper
use of this furnace can cause seri-
ousinjuryordeathfromburns,fire,
explosion, electrical shock, and
carbon monoxide poisoning.
DANGER: Carbon monoxide
poisoning may lead to death!
WARNING: Any change to
this heater or its controls can
be dangerous.
Do not place clothing or other
flammable material on or near
the appliance. Never place any
objects on the furnace.
Surfaceoffurnacebecomesvery
hot when running furnace. Keep
children and adults away from
hot surface to avoid burns or
clothingignition.Furnacewillre-
main hot for a time after shut-
down. Allow surface to cool be-
fore touching.
Due to high temperatures, the
appliance should be located out
oftrafficandawayfromfurniture
and draperies.
Carefully supervise young chil-
dren when they are in the same
room with furnace.
Turnofffurnaceandunplugandlet
cool before servicing. Unless you
need gas supply for testing, shut
off equipment shutoff valve before
servicing. Only a qualified service
person should service and repair
furnace and venting system.
Replace any safety screen or
guard removed for servicing be-
fore operating furnace.
You must keep control compart-
ments, burners, and circulating
airpassagesclean.Morefrequent
cleaning may be needed due to
excessive lint and dust from car-
peting, bedding material, etc.
Turnoffthegasvalveandunplug
before cleaning furnace.

3
201835
OWNER’S MANUAL
LOCAL CODES
Install and use furnace with care. Follow all
localcodes.Intheabsenceoflocalcodes,use
the latest edition of the following:
•National Fuel Gas Code ANS Z223.1,
also known as NFPA54 * (USA)
• National Electric Code ANS/NFPA 70*
•CAN/CGA-B149[.1 or .2] Installation
Codes** (Canada).
*Available from:
American National Standards Institute, Inc.
1430 Broadway
New York, NY 10018
National Fire Protection Association, Inc.
Batterymarch Park
Quincy, MA 02269
**Available from:
Standards Council of Canada
350 Sparks Street
Ottawa, Ontario K1R 7S8
This furnace must be grounded when in-
stalled. Follow all local codes. In the ab-
sence of local codes, refer to the National
ElectricalCodeANS/NFPANo.70(U.S.A.)
or CSA C22.1 Canadian Electrical Code,
Part I (Canada).
The installation must conform with local
codes,intheabsenceoflocalcodes,withthe
National Fuel Gas Code, ANS Z223.1/Ca-
nadianInstallationCode,CAN/CGAB149.
When installing furnace in a manufactured
(mobile) home, follow the Manufactured
Home Construction and Safety Standard,
Title 24CFR, Part 3280 (formerly the Fed-
eral Standard for Mobile Home Construc-
tion and Safety, Title 24, part 280; 1975).
When such a standard is not applicable,
followtheStandardforManufacturedHome
Installations, 1982 (Manufactured Home
Sites, Communities, and Set-Ups), ANS
A225.1/NFPA 501A.
InCanada,installfurnaceinaccordancewith
StandardCSAZ240.4-GasEquippedRecre-
ational Vehicles and Mobile Housing and
any applicable local codes and regulations.
Appliance input ratings are based on sea
leveloperation and need not be changedfor
operation up to 2,000 feet elevation. For
operation at elevations above 2,000 feet,
manufactured to specified deration condi-
tions for Canada and the United States.
UNPACKING
1. Remove furnace from carton.
2. Remove all protective packaging ap-
plied to furnace for shipment.
3. Removethe following items from carton:
• Hardware package containing four
large screws, two small screws, and
thermostat mounting plate
• Hardware package (thermostat and
two screws)
• Equipment shutoff valve
If any of these items are missing,
promptly inform dealer where you
bought furnace.
4. Checkfurnaceforanyshipping damage.
If furnace is damaged, promptly inform
dealer where you bought furnace.
PRODUCT
FEATURES
HOT SURFACE IGNITOR
Thisfurnacehasanelectronicignitor.There
isnostandingpilot. Nomatchesorbatteries
are required.
THERMOSTATIC HEAT
CONTROL
The thermostat is temperature sensitive. It
automatically turns the furnace on and off.
This results in the greatest heating comfort.
This can also result in lower gas bills.
LIMIT SWITCH
Thelimitswitchshutsoffthegastothemain
burner if the furnace becomes too hot to
operate safely.
DNV25NB DNV40NB
*Rated Heating Input (BTU/Hr) 25,000 40,000
Thermal Output Capacity
(average loss calculation) 18,750 Btu/Hr 30,000 Btu/Hr
Type Gas Natural Only Natural Only
Ignition Hot Surface Ignitor Hot Surface Ignitor
Operating Amps 1.5 2
Volts/Cycles 120/60 120/60
Main Burner 1 2
Pressure Regulator Setting 3.5" W.C. 3.5" W.C.
Inlet Connection 3/8 NPT 3/8 NPT
Inlet Gas Pressure (in. of water)*
Maximum 7" 7"
Minimum 5" 5"
Dimensions, Inches (H x W x D)
Furnace 15 3/32 x 16 1/8x 23 5/815 3/32 x 21 3/4x 23 5/8
Weight (pounds)
Furnace 53 71
Shipping 65 98
* For purposes of input adjustment.
SPECIFICATIONS

4
201835
DIRECT-VENT NATURAL GAS HEATER
DYNAVENT
®
6" Minimum
Adjacent
Side
Wall
Ceiling
Finished Floor, Carpet, Tile, etc.
12"
Minimum
12" Minimum
Figure1-MountingClearancesasViewed
from Front of Furnace
The clearance between the cabinet and the
wall it passes through is 0 inches.
Provide the following minimum clearances
from furnace cabinet (portion of cabinet
extending into outside air, as viewed from
the rear of furnace) to obstructions:
Cabinet Back: 36 inches
Cabinet Sides: 6 inches
Cabinet Bottom: Must be high enough
off the ground to prevent snow, water,
leaves,oranyotherobjectsfromblock-
ing vents.
Minimum Clearances
Provide the following minimum clearances
from furnace front cover to combustibles
(as viewed from the front of furnace, see
Figure 1):
Below Front Cover: 6 inches
Above Front Cover: 12 inches
Adjoining Wall: 12 inches
Front: 8 feet
WARNING: Due to high tem-
peratures,neverinstallthefurnace:
• in an inside wall
• in a recreation vehicle
• inawindowrecessedinathick
wall (creating an alcove)
• in an alcove
• behindadoororwhereanopen
doorwouldblocknormalairflow
• as a fireplace insert
• in high traffic areas
• near furniture or draperies
• in windy or drafty areas
CAUTION: If you install the
furnace in a home garage, locate
furnacewheremovingvehiclewill
not hit it.
Forconvenienceandefficiency,installfurnace:
• where there is easy access for operation,
inspection, and service
• in a central location, near an electrical
outlet
• wherethere is adequate clearance around
vents outside
Before installing furnace, inspect the wall,
floor,andoutsideareas.Makesurethereare
nopipes,wiring,oranythingelsethatwould
interferewithfurnaceinstallation.Ifyouare
installing thermostat in a wall, make sure
there are no pipes or wiring in the hollow
wallabovethefurnace.Thethermostatwires
will pass through this wall from the attic.
Mounting hardware needed to mount fur-
nace into wall is included with the furnace.
No venting material is needed. You must
furnishtoolsand all gas piping from the gas
source to the furnace inlet.
INSTALLATION
WARNING: A qualified ser-
vice person must install furnace.
Have service person inspect fur-
nace before use and at least an-
nually. Follow all local codes.
CHECK GAS TYPE
Use only natural gas. If your gas supply is
not natural gas, do not install furnace. Call
dealer where you bought furnace for proper
type furnace.
INSTALLATION ITEMS
Before installing furnace, make sure you
have all items below:
• electric drill
• drill bits
• Phillips screwdriver
• hammer
• pipe wrench
• stud locator or small finishing nails
• equipment shutoff valve (supplied)
• test gauge connection (see Figure 15,
page 10)
• piping (check local codes)
• sealant (resistant to propane/LP gas)
• ground joint union
• sediment trap
• tee joint
LOCATING FURNACE
This furnace is designed to be mounted in a
wallthatis4to18inchesthick.Youcanalso
mount furnace in a window.
WARNING: Do not install fur-
naceininteriorwallofbuilding.You
mustinstallfurnaceinexteriorwall
of building. Rear of furnace must
extend into open, outside air. This
letspoisonousexhaustgasesven-
tilate to the outdoors.
WARNING:Maintainthemini-
mumclearancesshowninFigure
1.Ifyoucan,providegreaterclear-
ances from floor, ceiling, and
joining wall.
WARNING:Turnoff electrical
circuitsthatpassthroughthewall
whereyouaregoingtoinstallthe
furnace.
NOTICE: This furnace must be
electrically grounded. Follow all
local codes. In the absence of
local codes, follow the National
Electric Code, ANS/NFPA 70
(U.S.)orCanadianElectricalCode
Part I-CSA C22.1 (Canada).

5
201835
OWNER’S MANUAL
CREATING WALL OPENING
AND MOUNTING FURNACE
Remove furnace front cover. Remove the
twoscrewsattheloweredgesoffrontcover.
Lift front cover away.
Installing in Normal Frame Wall
The25,000BTU/Hrmodelisdesignedtofit
between two wall studs set at 16 inch on
center. The 40,000 BTU/Hr model will not
fit between wall studs. Follow the steps
below to install.
1. Turn off electrical circuits that pass
through mounting wall. Make sure
there are no pipes or electrical wires in
area you intend to cut.
2. Use stud locator or small finishing nail
to find wall studs. When you locate
studs, drive a small finishing nail into
each stud. This provides a visual refer-
ence for stud locations.
3. 25,000 BTU/Hr Model: Cut an open-
inginwallbetweenthetwostuds.Make
opening 14 1/4" wide by 13 5/8" high
(see Figure 2). IMPORTANT: You
must install furnace horizontally. Do
not install furnace vertically.
40,000 BTU/Hr Model: Cut a 20 5/16"
wideby143/8"high opening in wall(see
Figure 2). Start your cut right next to
stud you are going to anchor cabinet to.
Cut across wall and through the next
stud. Stop cut at proper width.
IMPORTANT: You must installfurnace
horizontally. Do not install furnace ver-
tically.
4. 25,000 BTU/Hr Model: Mark screw
locations on wall (see Figure 2). Make
sure screws will anchor into studs.
Makesurescrewlocations match screw
holes on cabinet flange.
40,000 BTU/Hr Model: Mark screw
locations on wall (see Figure 2). Make
surescrewson one side will anchor into
studs. Screws on other side will only
anchor in wall material. Make sure
screw locations match screw holes on
INSTALLATION
(Continued)
Figure 2 - Wall Openings and Screw
Locations
Wall Studs
Wall
Opening
14 1/4"
13 5/8"
Approx.
Screw
Locations
Wall Studs
20 5/16"
14 3/8"
Wall Opening
Approx.
Screw
Locations
25,000 BTU/Hr Model
cabinet flange.
5. 25,000 BTU/Hr Model: Use a proper-
sized drill bit. Drill holes through wall
and into studs at marked locations.
40,000 BTU/Hr Model: Use a proper-
sized drill bit. On wall stud side of
opening, drill holes through wall and
intostudsatmarked locations. On other
side, drill holes through wall material.
6. Insert furnace into opening. Do this
from inside the room. Secure furnace
towallwith four largescrewsprovided.
7. On outside of wall, caulk opening be-
tween the cabinet and the rough edges
of opening.
40,000 BTU/Hr Model
Approx.
Screw
Locations
Installing in Masonry Wall
You can mount both models in a masonry
wall. Follow the steps below to install.
1. Cut opening in wall. Make opening 14 1/4"
wideby135/8" high for 25,000 BTU/Hr
models. Make opening 20 5/16" wide by
14 3/8" high for 40,000 BTU/Hr mod-
els. IMPORTANT: You must install
furnace horizontally. Do not install fur-
nace vertically.
INSTALLING THERMOSTAT
Mount the thermostat directly on the fur-
naceoronawallinanotherpartoftheroom.
If you have solid or masonry walls, mount
the thermostat on the furnace.
Mounting Thermostat to Furnace
1. Unplug furnace.
2. Locate red and white thermostat wires
coming out of side of furnace. These
wires are labeled “Thermostat.”
3. Cut thermostat wires to desired length.
4. Route thermostat wires through slot/
hole in side of thermostat mounting
plate. Then route wires through 5/8"
diameter hole in center of plate (see
Figure 4, page 6).
5. Connect thermostat wires to the two
terminal screws on back of thermostat
(see Figure 3). Connect red wire to “R”
terminal. Connect white wire to “W”
terminal.
WARNING: Unplug furnace
before installing thermostat.
2. Secure furnace to wall with toggle bolts
or hook bolts set in mortar.
3. Insert furnace into opening. Do this
from inside the room. Secure furnace
to wall with toggle bolts or hook bolts.
4. On outside of wall, caulk opening be-
tween the cabinet and the rough edges
of opening. You can also use mortar to
seal opening.
Figure 3 - Connecting Thermostat Wires
to Thermostat
Continued
W
R
Red Wire
White Wire

6
201835
DIRECT-VENT NATURAL GAS HEATER
DYNAVENT
®
Locating Thermostat on Wall
1. Locate thermostat 4 1/2to 5 feet above
the floor on an inside wall away from
any heat sources. The thermostat needs
to sense average room temperature.
Avoid the following:
HOT SPOTS
Concealed pipes or ducts
Fireplaces
Registers
TV sets and radios
Lamps or direct sunlight
Kitchen
COLD SPOTS
Concealed pipes or ducts
Stairwells (drafts) or doors (drafts)
Unheated rooms on other side of wall
DEAD SPOTS
Behind doors
Corners and alcoves
2. Before installing thermostat, inspect the
wall, floor, and attic areas. Make sure
there are no pipes, wiring, or anything
else that would interfere with install-
ing thermostat. Do not mount thermo-
stat to stud. If there are any obstruc-
tions, choose a new location.
6. Attach thermostat to thermostat mount-
ingplatewithscrews provided (see Fig-
ure 4). IMPORTANT: Note mounting
plate position in Figure 4. Correctly
position mounting plate for your model
furnace.
7. Insert thermostat mounting plate be-
tween wall and cabinet flange. Line up
top notch on mounting plate with top
screw on flange (see Figure 5).
IMPORTANT: Thermostat for 25,000
BTU/Hr model mounts on right side of
furnace (see Figure 5). Thermostat for
40,000 BTU/Hr model mounts on left
side of furnace (see Figure 5).
8. Insert screw in cabinet flange and ther-
mostatmountingplateandtightenfirmly.
IMPORTANT: Make sure thermostat
wiresdo not touch combustion chamber.
INSTALLATION
(Continued)
.2
.3
.4
.5
.7
1.0
SOLID STATE IGNITION
50 60 70 80 90
50 60 70 80 90
OFF
40,000 BTU/Hr Models
00000000000 00000000
00 00 00 00 00
00 00 00 00 00
SOLIDSTATEIGNITION
50 60 70 80 90
50 60 70 80 90
25,000 BTU/Hr Models
40,000 BTU/Hr Models
Figure5-InsertingThermostatMounting
Plate Between Wall and Cabinet Flange
Figure 4 - Attaching Thermostat to
Thermostat Mounting Plate
.2
.3
.4
.5
.7
1.0
SOLID STATE IGNITION
50 60 70 80 90
50 60 70 80 90
OFF
25,000 BTU/Hr Models
3. Provide two 18-gauge insulated stranded
wires for the thermostat wire. Also pro-
vide two wire nuts, and two wall anchors.
Thereisaredandawhitethermostatwire
coming from the furnace. The extra ther-
mostat wires you furnish attach to these
wires. Make sure you furnish a red and a
white wire. This will insure correct
hookup.Purchaseenoughthermostatwire
to go from the furnace to the thermostat
location. Do not cut and splice this wire.
The thermostat wire must be unbroken.
Routing Thermostat Cable
All wiring must meet local codes. The fol-
lowing instructions cover routing the wire
through the attic. You can run wiring from
a basement or crawl space.
1. Unplug furnace.
2. Beforedrillingholein wall,driveasmall
finishing nail through ceiling directly
above thermostat location. Pull nail out
andpushasmallstiffwirethroughhole.
Thishelpsyoulocatethermostat mount-
ing location when in attic.
3. In attic, locate stiff wire. Drill 1/2" hole
in center of ceiling wall plate next to
stiff wire. Remove wire.
4. Probe through drilled hole in wall plate
with a stiff wire to make sure there are
no pipes, wiring, or anything else
blocking the way for thermostat wires.
If you find blockage, choose new loca-
tion for thermostat.
5. Drill a 1/2" hole through the wall at
thermostat mounting location.
6. From attic, feed thermostat wires
through hole in ceiling plate until wires
reach thermostat location.
7. Make a small hook with a piece of stiff
wire. Run wire hook through 1/2" hole
in wall. Hook thermostat wires. Pull
wires through hole in wall. Make sure
6" of wires stick out.
8. Drive a small finishing nail in ceiling
above furnace.
25,000 BTU/Hr Model - Drive nail
above right side of furnace.
40,000 BTU/Hr Model - Drive nail
above left side of furnace.
Pull nail out and push a small stiff wire
throughhole.This helps you locate wire
routing location when in attic.
9. Repeat steps 3 and 4 above.

7
201835
OWNER’S MANUAL
10. Feed thermostat wires from attic to
furnace through 1/2" hole in ceiling
wall plate.
11. Connect thermostat wires from attic to
thermostat wires on furnace. Connect
red wires together, then connect white
wires together. Use wire nuts to make
connections. IMPORTANT: Makesure
thermostat wires do not touch combus-
tion chamber.
INSTALLATION
(Continued)
Mounting the Thermostat to Wall
1. Connect thermostat wires to the two
terminal screws on back of thermostat
(see Figure 6). Connect red wire to “R”
terminal. Connect white wire to “W”
terminal.
2. Push any excess wire back through hole
in wall and plug hole with insulation
to prevent drafts. Drafts affect the ther-
mostat operation.
3. Use thermostat base to mark mounting
screw locations.
4. Drillproper-sized holesforwallanchors.
5. Attach thermostat to wall using screws
provided (see Figure 7).
W
R
Red Wire
White Wire
Figure 7 - Mounting Thermostat to Wall
.2
.3
.4
.5
.7
1.0
SOLID STATE IGNITION
50 60 70 80 90
50 60 70 80 90
OFF
Figure 6 - Connecting Thermostat Wires
to Thermostat
Wall
Anchors
CAUTION: Use only new,
black iron or steel pipe. Copper
tubing may be acceptable in cer-
tain areas. Check local codes.
Use pipe large enough in diam-
eter to allow proper gas volume
to furnace. If pipe is too small,
undue loss of pressure will oc-
cur. Refer to chart on page 9.
WARNING: Unplug furnace
beforeconnectingtogassupply.
WARNING: Never connect
furnacetoprivate(non-utility)gas
wells. This gas is commonly
known as wellhead gas.
WARNING: A qualified ser-
vice person must connect fur-
nace to gas supply. Follow all
local codes.
CAUTION: Lightly apply pipe
joint sealant to male threads be-
fore connecting. Use pipe joint
sealant that is resistant to liquid
petroleum (LP) gas.
CONNECTING TO GAS
SUPPLY
All piping must comply with local codes
and ordinances or with the National Fuel
Gas Code (ANS Z223.1 NFPA No. 54),
whichever applies.
You can connect furnace to gas supply at
frontof furnace(inside)oratrearoffurnace
(outside).
Connecting Furnace to Gas
Supply at Front of Furnace
1. Locate gas inlet pipe on lower, right
front of furnace (see Figure 8).
2. Connect 3/8" NPT pipe or nipple to gas
inlet pipe (see Figure 8). See Provid-
ingGas Piping to Furnace, pages 9 and
10, for correct gas pipe installation.
Continued
Gas Inlet Pipe
Figure 8 - Connecting Gas from Inside of
Room
3/8" NPT
Pipe or
Nipple

8
201835
DIRECT-VENT NATURAL GAS HEATER
DYNAVENT
®
WARNING:Neveruseanopen
flame to check for a leak. Apply a
mixture of liquid soap and water
toalljoints.Bubblesformingshow
a leak. Correct all leaks at once.
Figure 14 - Inserting Pipe through
Knockout Hole
Figure 13 - Location of Knockout Plug
Knockout Plug
Connecting Furnace to Gas
Supply at Rear of Furnace
1. Remove the two screws in back of fur-
nace cabinet located by the exhaust
vent(s) (see Figures 9 and 10).
2. Remove two screws on front lower
flange that attach furnace flange to fur-
nace cabinet flange (see Figure 11).
Note: 40,000BTU/Hr model has a bot-
tom shield (see parts list, page 22, for
location). Removing two screws will
detach bottom shield.
3. Slide furnace out of furnace cabinet.
4. Locate gas inlet pipe on lower, right
front of furnace.
5. 40,000 BTU/Hr Model Only: Remove
screw holding gas inlet pipe clamp to
furnace.
6. Disconnect gas inlet pipe from 3/8"
manifold elbow. Turn gas inlet pipe
counterclockwise to disconnect (see
Figure 12).
7. Rotate the 3/8" manifold elbow 90°so
the opening is pointing downward (see
Figure 12).
8. Locate knockout plug in furnace cabi-
net. Knockout plug is in lower left rear
offurnacecabinet(as viewed from rear,
seeFigure 13). Remove knockout plug.
9. Slide furnace back into furnace cabi-
net.Make sure exhaust tube gaskets are
in place. Make sure exhaust and intake
vent tubes extend into vent caps on
back of cabinet. Replace two screws by
exhaust vent(s) removed in step 1.
10. 25,000 BTU/Hr Model: Replace two
screws removed in step 2. Attach fur-
nace flange and furnace cabinet lower
flange together.
40,000 BTU/Hr Model: Place bottom
shield back in place. Replace two
screws removed in step 2. Attach bot-
tom shield, furnace flange, and furnace
cabinet lower flange together.
INSTALLATION
(Continued)
Figure 9 - Locations of Screws in Back of
Furnace Cabinet (25,000 BTU/Hr Model)
Figure 10 - Locations of Screws in Back
ofFurnaceCabinet(40,000BTU/HrModel)
Figure 11 - Removing Screws on Lower
Flange (40,000 BTU/Hr Model Shown)
Figure 12 - Disconnecting Gas Inlet Pipe
(40,000 BTU/Hr Model Shown)
Remove Screw,
40,000 BTU/Hr
Model Only
Gas Inlet
Pipe Manifold Elbow
Furnace
Flange
Furnace
Cabinet
Flange
11. Run 3/8" pipe or nipple through knock-
out hole. Connect 3/8" pipe or nipple
to manifold elbow (see Figure 14). See
Providing Gas Piping to Furnace,
pages 9 and 10 for correct gas pipe in-
stallation.
12. Check connections for gas leak.
13. Caulk around pipe or nipple. This pre-
vents cold air entering knockout hole.
3/8" NPT

9
201835
OWNER’S MANUAL
Providing Gas Piping to Furnace
Youmustprovidegaspipingfromgassourcetofurnace.Thegaspipingmustbeinavertical
position where it connects to the furnace. This prevents interference with front cover
installation.
Consult your local gas company for proper routing of the gas lines.
Pipesizeisdetermined by the length of pipe from the gas source to the furnaceandthetotal
BTU load on the gas source.
AddthetotalBTUsrequiredforallappliancesconnectedtothegassourceincludingthisfurnace.
Divide this number by 1030. This will give you the approximate cubic feet per hour needed.
Example:
40,000 BTU/Hr
+ 15,000 BTU/Hr for other gas appliances
55,000 BTU/Hr total
55,000 ÷1030 = 53.4
Locate 53.4 or higher on chart below.
According to the chart below, you should use 50 feet or less of 1/2" pipe, 200 feet
or less of 3/4" pipe, etc...
MINIMUM
IRON PIPE
SIZE LENGTH OF PIPE (FEET)
10 20 30 40 50 60 70 80 90 100 125 150 175 200
3/8" 72 49 40 34 30 27 25 23 22 21 18 17 15 14
1/2" 132 92 73 63 56 50 46 43 40 38 34 31 28 26
3/4" 278 190 152 130 115 105 96 90 84 79 72 64 59 55
1" 520 350 285 245 215 195 180 170 160 150 130 120 110 100
1
1
/4"1050 730 590 500 440 400 370 350 320 305 275 250 225 210
1
1
/2"1600 1100 890 760 670 610 560 530 490 460 410 380 350 320
2" 3050 2100 1650 1450 1270 1150 1050 990 930 870 780 710 650 610
2
1
/2"4800 3300 2700 2300 2000 1850 1700 1600 1500 1400 1250 1130 1050 980
3" 8500 5900 4700 4100 3600 3250 3000 2800 2600 2500 2200 2000 1850 1700
4" 17500 12000 9700 8300 7400 6800 6200 5800 5400 5100 4500 4100 3800 3500
IMPORTANT: Checkgaslinepressureatgasmeterbeforeconnectingfurnacetogasline.Gas
linepressuremustbenolessthan5inches of water and no greater than 7 inches of water. Gas
pressures and input to the burners must not exceed the rated input and pressure shown on the
rating plate. For natural gas, manifold pressure should be 3.5 inches of water. For elevations
above 2000 feet, reduce rating 4% for each 1000 feet above sea level (U.S.A. only).
INSTALLATION
(Continued)
Continued

10
201835
DIRECT-VENT NATURAL GAS HEATER
DYNAVENT
®
INSTALLATION
(Continued)
CHECKING GAS
CONNECTIONS
WARNING: Test all gas pip-
ing and connections for leaks
after installation or servicing.
Correct all leaks at once.
WARNING:Neveruseanopen
flame to check for a leak. Apply a
mixture of liquid soap and water
toalljoints.Bubblesformingshow
a leak. Correct all leaks at once.
Pressure Testing Gas Supply
Piping System
Test Pressures In Excess Of 1/2 PSIG
(3.5 kPa)
1. Disconnect appliance with its appliance
main gas valve (control valve) and
equipment shutoff valve from gas
supply piping system. Pressures in
excess of 1/2 psig (3.5 kPa) will
damage heater regulator.
2. Cap off open end of gas pipe where
equipmentshutoffvalve was connected.
3. Pressurizesupply piping system by either
usingcompressedairoropeningmaingas
valve located on or near gas meter.
4. Check all joints of gas supply piping
system. Apply mixture of liquid soap
and water to gas joints. Bubbles form-
ing show a leak.
5. Correct all leaks at once.
6. Reconnect furnace and equipment
shutoff valve to gas supply. Check re-
connected fittings for leaks.
Installation must include an equipment
shutoffvalve(supplied),groundjointunion,
plugged 1/8" NPT tap, and a sediment trap.
Locate NPT tap within reach for test gauge
hook up. NPT tap must be upstream from
furnace (see Figure 15).
Install an equipment shutoff valve in an
accessible location. The equipment shutoff
valveisforturningonorshuttingoffthegas
to the appliance.
Apply pipe joint sealant lightly to male
threads. Prevent excess sealant from going
intopipe.Excesssealantinpipecouldresult
in clogged furnace valves.
Installsedimenttrapinsupplylineasshown
in Figure 15. Locate sediment trap where it
iswithinreachforcleaning.Asedimenttrap
trapsmoistureandcontaminants.Thiskeeps
them from going into furnace controls. If
sediment trap is not installed or is installed
wrong, furnace may not run properly.
IMPORTANT: Locatesedimenttrapwhere
trapped matter will not freeze. Install sedi-
ment trap in a vertical run of pipe. If gas
piping enters furnace from rear (outside),
youmustlocatesedimenttrapincrawlspace
(see Figure 15). If you install furnace in
structure with slab foundation, you must
installgaspipingtofrontoffurnace(inside)
(see Figure 15).
CAUTION:Usepipejointseal-
ant that is resistant to liquid pe-
troleum (LP) gas.
Slab Floor Installation
Equipment
Shutoff Valve
Test Gauge
Connection
To Gas Supply
3" Min.
Sediment
Trap
Gas Piping
Entering
Furnace
Front
(Inside)
Gas Piping
Entering
Furnace
Rear
(Inside)
To Gas Supply
Equipment
Shutoff
Valve
3" Min.
Sediment
Trap
Crawl Space Installation
Test Gauge
Connection
Figure 15 - Gas Connection

11
201835
OWNER’S MANUAL
O
POSI
P
O
Off Position
On Position
Figure 16 - Equipment Shutoff Valve
Test Pressures Equal To or Less Than
1/2 PSIG (3.5 kPa)
1. Close equipment shutoffvalve (see Fig-
ure 16).
2. Pressurizesupply piping system by either
usingcompressedairoropeningmaingas
valve located on or near gas meter.
3. Check all joints from gas meter to
equipment shutoff valve. Apply mix-
ture of liquid soap and water to gas
joints. Bubbles forming show a leak.
4. Correct all leaks at once.
Pressure Testing Furnace Gas
Connections
1. Open equipment shutoffvalve (see Fig-
ure 16).
2. Open main gas valve located on or near
gas meter.
3. Make sure control knob of furnace is
in the OFF position.
4. Check all joints from equipment shutoff
valve to gas inlet pipe. Apply mixture
of liquid soap and water to gas joints.
Bubbles forming show a leak.
5. Correct all leaks at once.
6. Turn on furnace (see Operating Fur-
nace, pages 12 and 13). Check the rest
of the internal joints for leaks.
7. Turn off furnace (see To Turn Off Gas
to Furnace, page 13).
INSTALLATION
(Continued)
ATTACHING CABINET
FRONT COVER
CAUTION:Donotoperatefur-
nacewithfrontcoverremovedor
mounted wrong. If front cover is
mounted wrong, you cannot se-
cure it to cabinet with screws.
1. Hook top of front cover over top cabi-
net flange.
2. Secure the sides of front cover to lower
sides of furnace cabinet with two
screws provided (see Figure 17).
IMPORTANT: Youmayhaveremovedfur-
nace from furnace cabinet during installa-
tion. You must correctly install furnace
within cabinet. If not, front cover will not
properly attach to cabinet. Make sure gas-
kets for intake and exhaust tubes are in
place. Make sure intake and exhaust tubes
extend into vent caps on cabinet back and
are secured with screws. Make sure you
securedflangeonbottomoffurnacetoflange
on bottom front of cabinet.
Figure 17 - Attaching Front Cover to
Cabinet
CONNECTING TO
ELECTRICAL SUPPLY
IMPORTANT: Followalllocalcodeswhen
connecting electricity to furnace. In the ab-
sence of local codes, refer to the latest edi-
tion of the National Electrical Code ANS/
NFPA No. 70. If you are not familiar with
wiringcodes,haveaqualifiedelectriciando
the wiring.
It is best to plug furnace into a separate and
permanent electrical line circuit.
1. Supply a 120-volt, 60-cycle, grounded
outlet at furnace location.
2. The furnace has a three-pronged
(grounded) plug. Use only a grounded,
three-prong outlet.
IMPORTANT: Some local codes require
rigid or semi-rigid conduit or metallic
sheathe cable. When using a semi-rigid or
metallic sheathe cable, the installer must
terminate the supply wire in the terminal
box opening.
Performance Check
Plug furnace into three-pronged outlet. If
ignitor remains on after main burner igni-
tion or if the valve chatters, you may have
reversed polarity.
1. Unplug furnace.
2. Turn off electricity to outlet.
3. Reverse 120-volt connections inside
outlet.
4. Turn on electricity to outlet.
5. Plug in furnace. Ignitor should turn off
aftermainburnerignites. If ignitor does
not turn off, or if valve continues to
chatter, turn off furnace and unplug.
Call a qualified service person.

12
201835
DIRECT-VENT NATURAL GAS HEATER
DYNAVENT
®
WARNING: Furnace burner,
combustion chamber, and ex-
haust port are very hot during
operation. Keep children and
adults away from hot surfaces to
avoid burns and clothing igni-
tion. Carefully supervise young
children when they are in the
same room as furnace. Furnace
will remain hot for a time after
shutdown. Let surface cool be-
fore touching.
OPERATING
FURNACE
WARNING: Do not operate
furnacewithfrontcoverremoved.
Unsafe operation could result.
CAUTION: Do not block cir-
culating air openings in the lou-
ver of the front cover. This is
necessary for furnace to operate
properly.
FOR YOUR SAFETY
READ BEFORE
LIGHTING
WARNING: If you do not fol-
low these instructions exactly, a
fireorexplosionmayresultcaus-
ing property damage, personal
injury, or loss of life.
A. This appliance does not have a pilot.
Itis equipped withanignitiondevice
which automatically lights the
burner.Donot try tolighttheburner
by hand.
NOTICE: If operating furnace for
the first time, a slight odor will
occur. This odor will go away
after a few hours of operation.
OPERATING
INSTRUCTIONS
WARNING: Always follow
lighting instructions. Never at-
tempttolightburnerwithamatch
or butane torch.
1. STOP! Read the safety information,
column 1.
2. Set the thermostat to lowest setting.
3. Turn off all electric power to the
furnace.
4. Turn equipment shutoff valve clock-
wise to OFF position (see
Figure 18).
5. Wait five(5) minutes toclearoutany
gas. Then smell for gas, including
near the floor. If you smell gas,
STOP! Follow “B” in the safety in-
formation, column 1. If you don’t
smell gas, go to next step.
6. Turn equipment shutoff valve coun-
terclockwise to ON position
(see Figure 18).
7. This furnace is equipped with an ig-
nition device which automatically
lights the burner. Do not try to light
the burner by hand.
8. Plug in furnace.
9. Set thermostat to desired setting. If
thermostat is set above room tem-
perature, the blower will come on.
10. Allow approximately 45 seconds for
ignition to occur. When ignition oc-
curs, the glo-bar will stay on for a
short period of time.The flamesens-
ingprobewillsensethe burnerflame
and shut off glo-bar.
If ignition does not occur within 22
seconds, the ignition control will at-
tempt to light burner three times.
This will take about two minutes. If
ignition does not occur, the ignition
control will lock out the glo-bar and
valve circuit. Air in the gas line or a
short gas interruption will prevent
furnace from igniting. If this hap-
pens, turn thermostat off and wait 5
minutes. Turn the thermostat back
on. The furnace will try to ignite
again.
11. If the furnace still does notignite,fol-
low instructions To Turn Off Gas to
Furnace, page 13. Call a qualified
service person. Do not attempt to re-
start furnace.
Figure 18 - Equipment Shutoff Valve
O
POSI
P
O
Off Position
On Position
B. BEFORE OPERATING smell all
aroundtheappliancearea forgas. Be
suretosmellnexttothefloorbecause
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.
• Donottouchanyelectric switch;do
notuseany phone in your building.
• Immediatelycallyourgassupplier
from a neighbor’s phone. Follow
the gas supplier’s instructions.
• If you cannot reach your gas sup-
plier, call the fire department.
C. Use only your hand to turn the
handle on the equipment shutoff
valve. Never use tools. If the handle
will not turn by hand, don’t try to
repairit. Call aqualifiedservicetech-
nician. Force or attempted repair
may result in a fire or explosion.
D. Do not use this appliance if any part
has been under water. Immediately
call a qualified service technician to
inspect the appliance and to replace
any part of the control system and
any gas control which has been un-
der water.

13
201835
OWNER’S MANUAL
OPERATING
FURNACE
(Continued)
1. Set thermostat to lowest setting
2. Turn equipment gas valve clockwise
to OFF position. Do not
force equipment gas valve.
3. Unplugfurnaceifserviceistobeper-
formed.
To Shut Down Furnace for an
Extended Period of Time
1. Turn equipment gas valve clockwise
to OFF position. Do not
force equipment gas valve.
2. Set thermostat on OFF.
TO TURN OFF GAS
TO FURNACE
CAUTION:Donottrytoadjust
heatinglevelsbyusingtheequip-
ment shutoff valve.
The thermostat responds to the room tem-
perature.When theroomtemperaturedrops
belowthe thermostatsetting,thethermostat
turns the furnace burner and blower on.
When the room temperature goes above the
thermostat setting, the thermostat turns the
furnace burner off. The blower will con-
tinue to blow about two to three minutes
after the burner goes out. The thermostat
keeps the room at a constant temperature.
THERMOSTAT
CONTROL
OPERATION
INSPECTING
BURNER FLAME
To observe burner flame, remove furnace
front cover. Remove the two screws at the
lower edges of front cover. Lift front cover
away. Locate viewing window on front of
combustion chamber. You can see burner
flame through this window.
Correct Burner Flame: Blue flame with
well-defined burner ports.
Incorrect Burner Flame: Yellow or lazy
flame without well-defined burner ports.
Ifburnerflameis incorrect, shutofffurnace
and contact a qualified service person.
Correct Flame
Pattern Incorrect Flame
Pattern
Figure 19 - Burner Flame Patterns
NORMAL
OPERATING
SEQUENCE
1. Whentheroomtemperaturedropsbelow
thethermostatsetting,thethermostatcalls
for heat. A 24-volt circuit is completed
through the time delay relay coil. After
three to five seconds, the contacts in the
relay close. The blowers come on.
2. One motor drives both the combustion
air blower and the circulating room air
blower. The combustion air blower
draws air from outside through the in-
take air vent. This air discharges into
the combustion chamber. The combus-
tion air blower then forces the combus-
tionproducts out of the exhaust tube(s).
The Combustion air blower is sealed
so that air does not pass between it and
the circulating room air blower.
3. Whenthe blower motor reaches 75%of
normalr.p.m.(threetofiveseconds),air
from the blower turns on the
microswitch. When the microswitch
activates, the electrical circuit is com-
pleted through the limit switch to the
control module. The glo bar begins to
glow. In about 15 seconds, the glo bar
becomeshotenoughto ignite theburner.
4. Another 24-volt circuit is completed
through the module to the main gas
valve. The valve opens. Gas passes
through the valve to the main burner.
The gas is ignited by the glo bar.
5. After the main burner ignites, theflame
detector senses the presence of flame.
This opens the circuit to the glo bar.
The glo bar shuts down.
6. The circulating room air blower pulls
return air in from the living area. This
air is heated as it flows past the com-
bustion chamber. The heated air is then
blown out into the room.
7. When the room temperature rises above
the thermostat setting, the circuit to the
valve opens and the burner shuts off.
8. The blower continues to run about two to
three minutes until the time delay relay
coilcools.When the coil cools, the circuit
to the motor opens. The blower shuts off.
LIMIT SWITCH
WARNING: Do not operate
furnacewithoutaproperly-work-
ing limit switch.
The limit switch will turn off the gas to the
main burner if the furnace becomes too hot.
When this happens, the main burner will go
out and the blower will continue to run for
two to three minutes. This usually happens
when circulating air is partially or com-
pletely blocked.
Occasionalcyclingof thelimitswitch isnot
bad. This indicates safe operation. Limit
switch cycling will most likely occur on
warm days. If this happens too often or for
a long period of time, the circulating air
system should be thoroughly cleaned by a
qualified service person.
If the circulating air system is cleaned and
the limit switch continues to shut down the
furnace, the limit switch is defective. A
defective limit switch cannot be repaired. It
must be replaced. For safety reasons, never
operate the furnace without a limit switch.

14
201835
DIRECT-VENT NATURAL GAS HEATER
DYNAVENT
®
WARNING: Turn off and un-
plug furnace and let cool before
cleaning. Turnequipmentshutoff
valve to OFF position. Only a
qualified service person should
service and repair furnace.
WARNING:Keepfurnaceclear
and free from combustible mate-
rials, gasoline, and other flam-
mable vapors and liquids.
CAUTION: You must keep
control areas, burner, and circu-
latingairpassagewaysoffurnace
clean. Inspect these areas of fur-
nace before each use. Have fur-
naceinspected yearlyby aquali-
fiedserviceperson.Furnacemay
needmorefrequentcleaningdue
to excessive lint from carpeting,
bedding material, pet hair, etc.
CLEANING AND
MAINTENANCE CAUTION: Label all wiring
prior to disconnection when ser-
vicingcontrols.Wiringerrorscan
cause improper and dangerous
operation.
Verifyproperoperation afterser-
vicing.
CABINET
Air Passageways
• Use a vacuum cleaner or pressurized air
to clean.
Exterior
• Use a soft cloth dampened with a mild
soap and water mixture. Wipe cabinet
and front cover to remove dust.
• Use a vacuum cleaner to remove dust
from front cover louvers.
EXHAUST AND INTAKE VENTS
Make sure the exhaust and intake vents are
not blocked. The intake combustion air and
the exhaust gases must be expelled to the
outside.Haveaqualifiedservicepersonclean
dirt and loose debris from vents annually.
GASKETS
Inspect all gaskets. If any gaskets show
signs of leakage or damage, replace them.
Safe operation of furnace depends on all
gaskets being tight.
FRONT COVER
Remove anything that may be blocking the
air to the louvers of the front cover.
COMBUSTION CHAMBER
AND MAIN BURNER
Check flame pattern of main burner often
(see Inspecting Burner Flame, page 13).
Havecombustionchamberandmainburner
cleaned if you have run the furnace with a
high yellow flame. Incomplete combustion
from lack of air causes the yellow flame.
This deposits soot inside the combustion
chamberandonthe burner.Contactaquali-
fied service person to clean combustion
chamber and main burner.
OUTSIDE VENT CAPS
Inspectoutsideventcapsforobstructionsor
soot. If soot is found, do not use furnace.
Contact a qualified service person to clean
furnace.

15
201835
OWNER’S MANUAL
TROUBLESHOOTING WARNING: Turn off and unplug furnace and let cool before servic-
ing.Unlessyouneedgassupplyfortesting,shutoffequipmentshutoff
valve before servicing. Only a qualified service person should service
and repair furnace.
Continued
www.desatech.com
Note: For additional help, visit DESA
International’stechnicalservicewebsite
at www.desatech.com.
Note: Alltroubleshootingitemsarelistedin
order of operation.
OBSERVED PROBLEM
No heat
POSSIBLE CAUSE
1. Thermostat off
2. Gas supply
3. Electrical connections and power
4. Motor
5. Malfunctioning microswitch
6. Gas valve
REMEDY
1. Check to be sure thermostat is calling for heat.
Wire to thermostat could be off terminal
2. Be sure equipment gas valve is in the open posi-
tion (level or parallel to gas line)
3. Be sure all electrical connections are secure
4. Motor must be operating at top speed before
burner will come on. If blower is not operating
at top speed, check voltage supply (minimum
100 voltsA.C.). If voltage supply is okay, check
for defective motor
5. Be sure the microswitch is sailing in far enough
to open the solenoid valve and to energize the
ignition control. If the switch is not sailing in,
cleananydustor dirt from the actuator pin. Other
reasons for the switch not sailing in are
A.Insufficient blower speed - Slow motor due to
faulty motor or lint and dust accumulation on
theblowerwheelsorrestrictionofreturnairto
the furnace
B. Faulty microswitch - Replace switch if cir-
cuit to ignition control is not completed when
switch is manually engaged. Switch should
also be replaced if blower motor running at
top speed fails to engage switch within six or
sevenseconds. Note: To service switch, com-
bustion chamber must be pulled out. Follow
steps 1, 2, 3, 9 and 10 on page 8 to remove
combustion chamber
6. Within 20 seconds after motor reaches 75% of
its r.p.m. and microswitch engages, check the
following:
A.Voltage at valve - If current is present but
valve is not opening, check wire connections
B. If wire connections okay - Replace valve
C. Novoltage at valve - Checkcircuitcompletion
through microswitch and limit switch as well
as wiring and wire connections. If no defects
are found, see Ignition Failures, page 16

16
201835
DIRECT-VENT NATURAL GAS HEATER
DYNAVENT
®
TROUBLESHOOTING
Continued
www.desatech.com
The electronic system is made up of two
parts: the ignition control and the glo bar.
The ignition control is the brain of the elec-
tronic system. It has several functions:
1. When the blower reaches full r.p.m., a
24-volt circuit is completed to the ig-
nition control. (Check across yellow
and orange wires.)
2. The red and blue wires at the ignition
control are the 120-volt input for the
glo-bar circuit. When the 24-volt cir-
cuit is completed, the ignition control
willcomplete the 120-volt circuit to the
glo bar and it begins to glow. (Check
this circuit across the two white wires
at the ignition control.)
3. After approximately 20 seconds, a 24-
volt circuit is completed through the ig-
nitioncontroltothegasvalve.(Thiscir-
cuit is checked from brown wire at ig-
nition control to a neutral ground.) This
circuit opens the valve, gas flows to the
burner and is ignited by the heat from
the glo bar. Note: Glo bar remains on.
4. When the burner flame is established,
the sensing probe will sense the pres-
ence of burner flame and open the glo-
bar circuit. The glo bar will then stop
glowing.
It is important to determine the type of
problembeingexperienced.Thentheproper
checkout procedure can be made. The fol-
lowing is a list of problems, how to identify
in which area the problem is located, and
how to correct it.
WARNINGS:
• Never connect unit or ignition
circuit to 230 volts.
• Neveroperateunitwithglobar
touching burner or any other
ground. Damage to ignition
control will occur.
• Be sure sensor probe never
touchesglobar.Thiswilldam-
age ignition control.
• If the ignition control is defec-
tive, it must be replaced. It is
not field-repairable.
CAUTION: Do not attempt to
repair the ignition control. This
may alter it and cause it to oper-
ate incorrectly.
IGNITION FAILURES
OBSERVED PROBLEM
No heat (continued)
POSSIBLE CAUSE
7. Blower not operating
8. Short cycling (motor goes on and off)
REMEDY
7. A. Check power supply to furnace
B. Check electrical connections at furnace
C. With thermostat points closed, check for cir-
cuitcompletionatmotor. If voltage is present,
replace motor. If no voltage is present at mo-
tor, check for:
• 24 volts on secondary coil or transformer. If
no voltage, replace transformer.
• If 24 volt transformer okay, check for circuit
completion across contacts on time delay
relay. Allow three to five seconds for con-
tact to close
• If circuit across contacts okay, check conti-
nuity of wiring in motor circuit
8. A. Check thermostat. Contacts should remain
closed. If contacts are breaking:
• Check thermostat anticipator setting. It
should be between .75 and 1.0
• If anticipator setting okay, check amp draw
across thermostat. If amp draw exceeds .65,
checkamp draw across coil of valve andtime
delay relay. Note: On initial operation of glo
bar, there is a momentary surge of approxi-
mately 4.0 amps
• If amp draw is within limits, check for shorts
in thermostat wiring
• If wiring is okay, replace thermostat

17
201835
OWNER’S MANUAL
www.desatech.com
OBSERVED PROBLEM
Ignition failures
POSSIBLE CAUSE
1. Glo bar will not glow - with blower run-
ning and microswitch engaged
2. Glo bar glows but burner will not
come on
3. Glo bar operating and gas valve open-
ing but burner will not light
4. If the ignitor remains on after main
burnerignitionor the valve chatters, re-
verse the 120-voltA.C. connections at
the wall receptacle
REMEDY
1. Check the following:
A. Check for 24 volts A.C. across yellow and
orange wires at ignition control. If no volt-
age, check microswitch and limit switch for
circuit completion as well as wiring and wir-
ing connections
B. Voltagepresentacrossyellowandorangewires,
check for 120-volt input to ignition control
across red and blue wires. If no voltage, check
wiring all the way back to power supply
C. 120 volts present across red and blue wires,
checkfor120voltsacrossthetwowhite wires
at ignition control. If no voltage, replace igni-
tion control
D. Voltage present across the two white wires,
check wiring and wire connections to glo bar
E. If wiring and wire connections okay, replace
glo bar. (Glo bar broken)
2. A. Check for voltage (24 volts A.C.) at valve
40 seconds after glo bar begins to glow. If
voltagepresentbutvalvenotopening,replace
valve
B. If no voltage at valve, check brown wire at
ignition control for continuity and good con-
nection
C. If wire and wire connections okay, replace
ignition control
3. A. Check gas flow through burner. If no gas is
coming through burner, check for obstruc-
tion in gas line, main burner orifice, or main
burner
B. If thermostat okay, check for 24 volt A.C.
circuit completion across yellow and orange
wires at ignition control. If no voltage, check
for circuit completion through limit switch
and microswitch
C. If voltage is present at ignition control across
yellow and orange wires yet burner contin-
ues to go off, replace ignition control
4. A. If polarity is okay yet burner continues to go
off,checkthermostattobesure it is still com-
pleting the valve circuit. If not, check for
excessive amp draw in valve circuit
B. If thermostat okay, check for 24 volt A.C.
circuit completion across yellow and orange
wires at ignition control. If no voltage, check
for circuit completion through limit switch
and microswitch
C. Voltage present at ignition control across
yellow and orange wires yet burner contin-
ues to go off, replace ignition control
Continued
TROUBLESHOOTING
Continued

18
201835
DIRECT-VENT NATURAL GAS HEATER
DYNAVENT
®
www.desatech.com
OBSERVED PROBLEM
Ignition failures
Excessive noise
Main burner will not cycle off
Furnace will not operate
POSSIBLE CAUSE
5. Burner cycles off and glo bar comes on
immediately, check the following:
1. Blower out of balance
2. Motor hums
1. Thermostat setting
2. Gas valve stuck open
1. Wiring connections or shorts
REMEDY
5. A. Check flame sensing probe. Be sure
probe is positioned in the burner
flameand glowing cherry red. Check
wire and wire connections at probe
and ignition control
B. If wire and wire connections okay,
check for voltage across brown and
orange wires at ignition control. If
no voltage, replace ignition control
C. If voltage present, check wiring and
wire connections at valve
D. If wire and wire connections okay,
replace valve
1. Replace blower
2. Replace motor
1. Check thermostat
2. Check gas valve. If stuck open, replace.
Do not attempt to repair valve!
1. Check all wiring to assure proper con-
nection or detect possible shorts
TROUBLESHOOTING
Continued

19
201835
OWNER’S MANUAL
1
2
3
4
5
6
7
Junction
Box
Black
Green
▲White
Black
White
White
Black
Transformer
White
Brown
Brown
Black
Motor Green
370 V.A.C.
Capacitor
5 MFD
Terminal Block
Black
ThermostatWhite Red Black
Yellow
Blue
Brown
Green
Black
Brown
White
Ignition
Control
Board
Probe
♦Black
White
White Glo-Bar
Gas Valve
Time Delay
Relay
Limit
Switch Sail Switch
★
▲
♦
White
115 V.A.C.
(Open)
Brown
Brown
Orange
White
White
Red
★★
Note:
1
2
3
4
5
6
7
Junction
Box
Black
Green
▲White
Black
Red
White
Black
Transformer
White
Brown
Brown Black
Brown
Motor Green
370 V.A.C.
Capacitor
5 MFD Yellow
Terminal Block
Black
ThermostatWhite Red Black
Yellow
Blue
Yellow
Brown
Green
Black
Brown
Orange
White
Ignition
Control
Board
Probe
♦Black
White
White Glo-Bar
Gas Valve
Time Delay
Relay
Limit
Switch Sail Switch
Note:
▲
♦
White
115 V.A.C.
White
(Open)
WIRING DIAGRAMS
Figure 21 - Wiring Diagram (40,000 BTU/Hr Model)
Figure 20 - Wiring Diagram (25,000 BTU/Hr Model)
Note: Use only original replacement parts.
Thiswillprotectyourwarrantycoveragefor
parts replaced under warranty.
PARTS UNDER WARRANTY
Contactauthorizeddealersof this product.If
theycan’tsupplyoriginalreplacementpart(s),
callDESAInternational’sTechnicalService
Department at 1-800-323-5190. When call-
ing DESA International, have ready:
• your name
• your address
• model and serial number of your furnace
• how furnace was malfunctioning
• typeofgasused(propane/LPornaturalgas)
• purchase date
Usually,wewillaskyoutoreturnthedefec-
tive part to the factory.
PARTS NOT UNDER
WARRANTY
Contact authorized dealers of this product.
If they can’t supply original replacement
part(s), either contact your nearest Parts
Central (see below) or call DESA
International’s Parts Department at 1-800-
972-7879. When calling DESA Interna-
tional, have ready:
• model number of your furnace
• the replacement part number
REPLACEMENT
PARTS

20
201835
DIRECT-VENT NATURAL GAS HEATER
DYNAVENT
®
These Parts Centrals are privately owned businesses. They have agreed to support our
customer’sneedsbyprovidingoriginalreplacementpartsandaccessories.Forcertainparts,
someParts Centralsmayreferyoutoadealer inyourarea.WhencallingaParts Central,ask
for the Parts Department.
PARTS CENTRALS
Howard Industries
8855 Washington Blvd.
Culver City, CA 90232
310-837-9100
www.howind.com
Victor Manufacturing
42 Rumsey Road
E. Hartford, CT 06108-1164
NY, NJ, DE, PA, MD
1-800-243-9360
203-289-4223
Fax: [phone]
www.fwwebb.com
Controlled Engineering
299 Roosevelt Road
Glen Ellyn, IL 60137-5618
630-469-7300
www.controld.com
Portable Heater Parts
342 N. Country Road 400E
Valparaiso, IN 46383-9704
1-800-362-6951
219-462-7441
www.portableheaterparts.com
[email protected]
[email protected]
F B D
1349 Adams Street
Bowling Green, KY 42103-3414
1-800-654-8534
[phone]
Fax: [phone]
[email protected]
Central Air Supply
424 North Rockwell
Oklahoma City, OK 73127-6119
405-495-0014
Halco Enterprises
208 Carter Drive, Unit 21
West Chester, PA 19382-4500
1-800-368-0803
610-430-7717
www.halcoenterprises.com
Laportes Parts & Service
2444 N 5th Street
Hartsville, SC 29550-7704
803-332-0191
Cans Unlimited, Inc.
P. O. Box 649
Taylor, SC 29687-0013
1-800-845-5301
803-879-3009
[email protected]
Hughes Supply
1311 S Fern Street
Arlington, VA 22202-2809
703-416-8555
Tuco Industrial Products
5223 180th St. SW, Suite 4A-1
Lynwood, WA 98037-4506
1-800-735-1268
425-743-9533
www.tucoheat.com
Auer Steel & Heating Supply
2935 W. Silver Spring Dr.
Milwaukee, WI 53209-4224
414-463-1234
www.auersteel.com
Master Parts Dist.
1251 Mound Ave. NW
Grand Rapids, MI 49504-2672
1-800-446-1446
616-791-0505
Fax: [phone]
ww.nbmc.com
Washer Equipment Co.
1715 Main Street
Kansas City, MO 64108-2195
KS, MO, AR
816-842-3911
Controls, Inc.
6820 Glenwood Ave.
Raleigh, NC 27612-7133
NC, SC, VA, MD
1-800-334-5886
919-787-2242
Tarantin Tank Co.
P.O. Box 6129
Freehold, NJ 07728-6129
1-800-922-0724
908-780-9340
www.tarantin.com
East Coast Energy
707 Broadway
W. Long Branch, NJ 07764-1542
1-800-755-8809
732-870-8809
www.njplaza.com/ecep
Dayton Hardware
P. O. Box 275
North Dayton Station
Dayton, OH 45404-0275
Ohio Only - 1-800-762-3426
937-258-3721
TECHNICAL
SERVICE
SERVICE HINTS
When Gas Pressure Is Too Low
• glo-bar glows, but burner will not ignite
When Gas Quality Is Bad
• burner will not stay lit
• burner will produce flames and soot
Youmayfeelyourgaspressureistoolowor
gas quality is bad. If so, contact your local
gas supplier.
You may have further questions about in-
stallation, operation, or troubleshooting. If
so,contactDESAInternational’sTechnical
Service Department at 1-800-323-5190.
You can also visit DESA International’s
technical service web site at
www.desatech.com.