DAKA 521FB User manual

DAKA 521FB Manual Page 1 of 32 January 2009
Rev. 2, June 2012
MODEL 521FB
WOOD-BURNING FURNACE MANUAL
Manufactured in the U.S.A. by
DAKA CORPORATION
955 Industrial Street NE
Pine City, Minnesota 55063
Phone: [phone] Fax: [phone]
www.dakacorp.com

DAKA 521FB Manual Page 2 of 32 January 2009
Rev. 2, June 2012
I. LIMITED WARRANTY
This model has been tested and listed in accordance with
Underwriters Laboratories Standard UL 391-2010 –March 2010 and Sept. 2010
for Solid Fuel Central and Supplementary Furnace by
Intertek Testing Services/Warnock Hersey Inc.
International Conference of Building Officials (ICBO) Report No. TL116
Council of American Building Officials (CABO) Report No. NER QA219
Purchase Date:
Purchased From:
Model #:
Serial #:
DAKA Corporation warrants the combustion chambers of its supplementary and central furnaces to be free of
defects in material or workmanship for five years (non-prorated) from date of sale. All other components, including
electronics, gaskets and grates, are covered in the same manner for a period of one year.
DAKA Corporation will repair or replace defective components, at our option, at no charge for parts and labor,
and will pay freight charge for one-way shipment for warranty claims during the first year. In second and
subsequent years, only parts and labor will be provided at no charge. DAKA Corporation is not responsible for
installation or dismantling costs.
The warranty is void if unit is not used in a residential service connected to conventional basement-type upflow
central heating system, if non-approved fuels are used in firing of units, or if unit is damaged due to accident,
improper installation or negligence.
For service under this warranty, contact selling dealer or DAKA Corporation, Customer Service Dept.,
955 Industrial St. NE, Pine City, MN 55063; telephone [phone] or email [e-mail].
Implied warranties including that of merchantability are expressly limited in duration to the duration of this
warranty. DAKA Corporation disclaims any responsibility for consequential damages. Some states do not allow
limitations on how long an implied warranty lasts, or the exclusion or limitation of incidental or consequential
damages, so this limitation and exclusion may not apply to you.
This warranty gives you specific legal rights and you also may have other rights that vary from state to state.
This is our exclusive written warranty.
SAVE
THESE
INSTRUCTIONS.
This furnace meets
U.S. Test Standard: UL 391-2010 –MARCH 2010 AND SEPT. 2010

DAKA 521FB Manual Page 3 of 32 January 2009
Rev. 2, June 2012
II. TABLE OF CONTENTS
DAKA 521FB
WOOD-BURNING FURNACE MANUAL
I. LIMITED WARRANTY..................................................................................................2
II. TABLE OF CONTENTS ............................................................................................... 3
III. FEATURES ..................................................................................................................4
IV. SPECIFICATIONS........................................................................................................5
V. OPTIONAL FURNACE ACCESSORIES ......................................................................6
VI. GENERAL WOOD-BURNING SAFETY ...................................................................7, 8
VII. CHECKING SHIPMENT...............................................................................................9
VIII. PLANNING YOUR INSTALLATION ......................................................................10-14
A. General
B. Clearances
C. Chimney
D. Supplementary/Add-on
E. Central
IX. ASSEMBLY INSTRUCTIONS ...............................................................................15-20
A. Components (Main)
B. Electrical components (Fan Control, Wiring)
C. Cold Air Return Filter Box
X. INSTALLATION.....................................................................................................21-25
A. Connecting to Ductwork
1. Supplementary/Add-On
2. Central
3. Alternative Connection Options
B. Connecting to Chimney
XI. OPERATING INSTRUCTIONS............................................................................. 26, 27
A. General
B. Operating Controls: Snap Disc Fan Control & Automatic Damper Control
C. Emergency
XII. MAINTENANCE INSTRUCTIONS..............................................................................28
XIII. TROUBLESHOOTING ............................................................................................... 29
XIV. PARTS LIST & EXPLODED VIEW............................................................................. 30

DAKA 521FB Manual Page 4 of 32 January 2009
Rev. 2, June 2012
III. FEATURES
5-Year Warranty –
5-year non-prorated warranty on
firebox; 1 year on all other materials.
See Written Warranty for details.
Snap Disc Thermostat –A
highly reliable independent
snap disc thermostat controls
blower.
Heavy Duty Cast Iron Grates –
High heat resistance provides
longer life.
2 Sides and
Back Fire Brick
Lining –Durable
construction for
long life and
consistent heat.
UL Tested by WHI –
Tested to UL Standard
391-2010 –March
2010 and Sept. 2010.
Ensures safety and
efficiency.
42,000 to
105,000 BTU’s –
Offers wide range
of heat output.
8 Hour Burn Time –
For average heating
output, up to 12 hours
of “overnight” heating
needs.
Complete 7
gauge (3/16”)
steel throughout
Firebox –Most
competitors offer
only a 10-gauge
firebox; approx.
half the strength of
a DAKA Furnace.
Heats Homes up
to 2,600 sq. ft. –
Largest heating
capacity for the
price available in
the market.
USE AS AN ADD-ON or CENTRAL FURNACE
–Add-on utilizes existing central ductwork and distribution system
–Central application has its own ductwork.
NOTE: Return Cold Air Filter Box included but not
shown. The filter box improves indoor air quality.
Large Fire Box
holds 90 lbs.of
22” logs – Allows
for maximum burn
time.
Automatic Damper Control –For
maintenance free, consistent heat;
automatically adjusts air supply to fire.
Backdraft Damper –
Factory-installed warm air
back draft damper is
included with every
521FB furnace.
Full Length Ash Pan –Makes ash handling
more convenient and reduces spillage; no
back on ash pan for ease of dumping.
2-8” Warm Air Outlets
–for secure connection
of 8” round duct pipe.
Heavy Duty Cast Iron
Door –Prevents warping
and maximizes efficiency.
Blower, 550 CFM –
1/10 HP helps maintain
CFM at higher static
pressures. Totally
enclosed, permanently
lubricated ball-bearings.

DAKA 521FB Manual Page 5 of 32 January 2009
Rev. 2, June 2012
IV. SPECIFICATIONS
DAKA MODEL 521FB WOOD-BURNING FURNACE SPECIFICATIONS
Manufacturer:
DAKA Corporation
Model:
521FB
U.L. Approval:
Tested to U.L. Standard 391–March 2010 & Sept. 2010 by WHI
Fuel Type:
Wood / Coal
Dimensions:
44” Height x 24” Width x 25-½” Depth
BTU Output:
42,000 –105,000 per hour
Fuel Capacity:
22” Log Length / 90 lb.
Air Outlet Size:
2 –8” round
Flue Outlet Size:
6” round
Weight:
432 lbs.

DAKA 521FB Manual Page 6 of 32 January 2009
Rev. 2, June 2012
V. OPTIONAL FURNACE ACCESSORIES
DAKA CORPORATION
955 Industrial St NE, Pine City MN 55063
Telephone: [phone] Fax: [phone]
Email: [e-mail] Website: www.dakacorp.com
Visit our website or call 1-800-884-3252
for pricing and shipping information.
273 - TWIN 550-CFM BLOWER KIT
For installations requiring additional air pressure, such as
for use as a central furnace. Kit includes one 550-cfm split-
capacitor blower, wiring and instructions. For use with
models 521FB/621/622, many earlier deluxe models.
258 –DUAL BLOWER RETURN COLD AIR FILTER BOX
With No. 273 twin blower kit installed, this galvanized filter
box covers both blowers. Takes one 14" x 25 x 1” paper
furnace filter (not included.).
218 -LARGE MULTI-SPEED BLOWER & FILTER BOX
Mounts on side of furnace to provide increased air delivery
for higher static pressure central furnace applications. Kit
includes a direct drive 1/3 HP motor with multi speeds
(select speed based on wiring configuration), squirrel cage
& housing assembly, galvanized sheet metal cold air return
filter box, mounting hardware & assembly instructions.
223 - HOT-TUBE™ DOMESTIC HOT WATER PREHEATER
Connects to present domestic hot water tank to provide
gallons of piping hot water. Weldless boiler pipe has working
pressure of 1200lbs./sq. in. Kit includes pre-heater pipe,
hardware, gaskets and instructions.
238D - SOFT COAL SHAKER GRATE KIT
Replaces wood-burning grate to permit burning of
bituminous and sub-bituminous coal in Deluxe models
311/411/521FB/621/622 above, many earlier models.
Includes extra -thick 3-section shaker grates and shaker rod
assembly & fire door with spinner knob.
`
253 - FORCED DRAFT CONVERSION KIT
Adds convenience of living area control of heat output of
Deluxe models 521FB and 621, many earlier models. Kit
includes 35-cfm draft blower, wall thermostat,
transformer/relay, controls, wiring and instructions.
283 - BAROMETRIC DRAFT REGULATOR
Installs in chimney connector to help provide constant draft
control, extend burn times, save fuel, avoid over-firing, and
reduce creosote formation. Adjustable from .02" to .08"
updraft. For 6" pipe. U.L. Listed.

DAKA 521FB Manual Page 7 of 32 January 2009
Rev. 2, June 2012
VI. GENERAL WOOD-BURNING SAFETY
STOP FOR SAFETY!
Safe assembly, operating and maintenance practices should
always be followed whenever using any equipment.
READ THROUGH THE ENTIRE MANUAL BEFORE BEGINNING
YOUR INSTALLATION OR OPERATING YOUR FURNACE.
FOLLOW ALL STEPS EXACTLY!
WARNING: Disconnect all power before making
electrical connection. For power supply connections,
use No. 14 AWG or larger wires acceptable for at
least 105C. Check local codes for acceptable
components.
WARNING: Do not over fire the furnace. Over firing
will happen if the fire door or ash door is left open
during operation. Such actions can result in very
dangerous operating conditions.
WARNING –Risk of fire! Do not operate with flue
draft exceeding .06” WC. (measured in water
column). Use of a draft gauge is highly
recommended. Follow gauge manufacturer’s
instructions. Gauges to measure chimney draft are
readily available at furnace shops and are
economical to purchase or rent. If a draft gauge is
not available, with the draft regulator fully installed
and a good fire burning, adjust the counterbalance
weight closer to the gate for as low a draft setting as
possible, without the fire dying or getting smoke-
back with the stove door slightly open. To obtain
higher heat levels, move the weight away from the
gate to increase the setting.
WARNING: Do not operate with fuel loading or ash
removal doors open. Do not store fuel or other
combustible material within marked installation
clearances. Inspect and clean flues and chimney
regularly.
WARNING: Do not operate furnace while under the
influence of drugs or alcohol.
WARNING: For further information on using your
furnace safely, contact the National Fire Protection
Association (NFPA) at www.nfpa.org.
WARNING: To prevent burns, always wear
protective clothing, leather hearth gloves and eye
protection, while tending the fire.
WARNING: While in operation, keep the fire door
and ash door closed at all times except while
tending the fire.
WARNING: Burn wood only or burn coal only.
CAUTION: Hot Surfaces! Keep children away. Do
not touch during operation. Maintain clearance to
combustibles as listed on nameplate. Refer to
product nameplate and manual for additional
information.
CAUTION: During a power failure, set auto damper
no higher than EPF setting. Remove furnace air
filter. Air jacket top and sides may be removed to
keep the firebox from overheating. DO NOT expect
the furnace to keep the house as warm as when
power is on. Do not attempt to increase heat output
by opening ash door or fire door.
CAUTION: Turn off all power to furnace
before cleaning.

DAKA 521FB Manual Page 8 of 32 January 2009
Rev. 2, June 2012
VI. GENERAL WOOD-BURNING SAFETY
Building Codes: Check local building and mechanical codes prior to installation to ensure
conformance with all requirements.
Home Insurance: Review home insurance policy for coverage.
Paint Odor: During initial start-up, the unit may omit fumes as the paint outside shell cures. Please
provide outside ventilation throughout the home to help clear the odor.
Ash Disposal: Ashes should be placed in a metal container with a tight-fitting lid. The closed
container of ashes should be placed on a non-combustible floor or on the ground –well away from all
combustible materials pending final disposal. The ashes may be disposed of by burial in the soil or
otherwise locally dispersed. They should be retained in the closed container until all cinders have
thoroughly cooled.
Creosote: Formation & Need for Removal
When wood is burned slowly, it produces tar and other organic vapors that combine with expelled
moisture to form creosote. The creosote vapors condense in the relatively cool chimney flue of a slow-
burning fire. As a result, creosote residue accumulates on the flue lining. When ignited, this creosote
makes an extremely hot fire.
The chimney connector and chimney should be inspected at least twice monthly during the heating
season to determine if a creosote buildup has occurred. If creosote has accumulated, it should be
removed to reduce the risk of a chimney fire.
SAFETY NOTICE
IF THIS FURNACE IS NOT PROPERLY
INSTALLED, A HOUSE/BUILDING FIRE
MAY RESULT. FOR YOUR SAFETY,
CONTACT LOCAL BUILDING OR FIRE
OFFICIALS ABOUT PERMITS,
RESTRICTIONS AND INSTALLATION
REQUIREMENTS FOR YOUR AREA.
REFER TO MARKING ON APPLIANCE
FOR ADDITIONAL INFORMATION.

DAKA 521FB Manual Page 9 of 32 January 2009
Rev. 2, June 2012
VII. CHECKING SHIPMENT
UNPACKING
DO NOT LIFT FULL CARTON THAT
CONTAINS FIREBRICK AND BLOWER FROM
INSIDE THE FIREBOX.
Open box and remove individual firebricks and
blower first.
Check piece count against parts list in back of
manual.
MISSING OR DAMAGED PARTS
PLEASE DO NOT RETURN THE PRODUCT
TO THE STORE WHERE PURCHASED.
CALL DAKA CORPORATION DIRECTLY.
1-800-884-3252 Monday through Friday
8:00 AM to 4:30 PM Central Time
It is our goal to send replacement parts to you
immediately after we receive your order.
In order to assist our Customer Service
Representative, please have the following
information available.
Furnace Model Number
Product Part Number
Description
Furnace Serial Number
We are committed to customer satisfaction and
are dedicating our efforts to earn your
continued support.
FIG. 2
FIG. 1

DAKA 521FB Manual Page 10 of 32 January 2009
Rev. 2, June 2012
VIII. PLANNING YOUR INSTALLATION
PLANNING YOUR INSTALLATION
Read through the entire manual before
beginning your installation. Follow all steps
exactly. Your Model 521FB Furnace can be
installed as a supplementary/Add-on Furnace
or as a free-standing central furnace with its
own plenum and ductwork.
Review the location options below and
determine how you are going to install your
system.
A. GENERAL
1. The DAKA 521FB wood-burning furnace is
designed for use only in conventional up
flow systems. It must deliver heated air to a
supply (warm air) plenum –never to
ductwork. When installed as an Add-On
furnace, the warm air supply from this
furnace must never be connected to the
cold-air return inlet of the primary furnace;
components of the primary furnace may
overheat causing damage to the primary
furnace.
2. Check local building and mechanical codes
prior to installation to insure conformance
with all requirements. Review home
insurance policy for coverage.
3. A qualified individual familiar with solid-fuel
systems must install this furnace.
4. Installation of this furnace in mobile homes
is prohibited.
5. For garage installation, check your local
building code ordinance.
6. Do not operate as a room heater.
DANGER –Risk of fire or
explosion –Do not burn garbage,
gasoline, drain oil or other
flammable liquids.
B. CLEARANCES
1) FLOOR PROTECTION
1. This furnace must be installed on a non-
combustible floor surface such as solid
concrete or 3/8” non-combustible floor protector
board. This surface must extend at least 16” in
front and 8” to both sides of the furnace and
also extend at least 2” out from the sides of the
chimney connector. See FIG. 3 for details.
FIG. 3
Dimensions shown are minimum
clear distances for floor protector or
non-combustible floor.

DAKA 521FB Manual Page 11 of 32 January 2009
Rev. 2, June 2012
VIII. PLANNING YOUR INSTALLATION
B. CLEARANCES –continued
2) Wall Clearances to Combustibles
See FIG. 4.
Furnace to sidewall: 18”
Flue to sidewall: 27”
Furnace to back wall: 32 ½”
Flue to back wall: 23”
Furnace to front wall: 48”
Non-combustible sidewall: 6”
Sides of DAKA furnace to primary
furnace: 9”
FIG. 4
Dimensions shown are minimum
distances to stay clear from combustible
walls.
C. CHIMNEY
1) General
Chimney Requirements:
1) Minimum 6” inside diameter
2) “Type HT” (High Temperature)-listed
appliance-type chimney or a code-complying
tile-lined masonry chimney.
3) Chimney must extend 3’ above roofline and
be at least 2’ higher than any point of roof within
10’. See FIG. 5.
DO NOT install more than two 90° degree
elbows in the flue pipe to help maintain proper
draft.
This furnace requires its own independent
chimney. DO NOT connect to a chimney flue
serving another appliance. See FIG. 6.
All horizontal runs must have a minimum
upward rise of ¼” per foot.
The chimney connector (smoke pipe leading to
chimney flue) must be of minimum 24-ga. pipe
with each section joined with three sheet metal
screws. All fissures should be sealed with
furnace cement. Do not use galvanized pipe as
the coating could melt and cause toxic fumes.
A stack thermometer is recommended. Stack
temperatures can be checked with a simple
surface-mounted or probe-type thermometer. It
is recommended to maintain normal operating
range of 300-600 ° F. Temperatures lower than
300° F indicate insufficient draft or inadequate
combustion air and may result in creosote
formation in chimney flue.
The maximum draft setting is a maximum of
.06” W.C. (measured in water column). Use of
a gauge is highly recommended. Follow gauge
manufacturer’s instructions. Gauges to
measure chimney draft are readily available at
furnace shops and are economical to purchase
or rent. If a draft gauge is not available, with
the draft regulator fully installed and a good fire
burning, adjust the counterbalance weight
closer to the gate for as low a draft setting as
possible, without the fire dying or getting
smoke-back with the stove door slightly open.
To obtain higher heat levels, move the weight
away from the gate to increase the setting.
[An optional DAKA barometric regulator #283 may be used in the
chimney connector to help increase furnace efficiency by maintaining
a consistent draft. See FIGS. 5 & 6 on page 12.]

DAKA 521FB Manual Page 12 of 32 January 2009
Rev. 2, June 2012
VIII. PLANNING YOUR INSTALLATION
C. CHIMNEY –continued
2) Chimney Options
a) Masonry –Before using an existing masonry
chimney, have the chimney inspected, cleaned
and make all necessary repairs before attaching
the furnace. The flue pipe and fittings you will
need to connect your furnace directly to a
masonry chimney are shown in FIG. 5. If the
flue pipe must go through a combustible wall or
ceiling before entering the masonry chimney,
consult a qualified mason or chimney dealer.
The installation must conform to all local building
and fire codes and the latest edition of the
National Association of Fire Protection (NFPA)
Publication 211. If there is a cleanout in the
base of the chimney, close it tightly. The
chimney flue pipe must not pass through an
attic or roof space, closet, or any concealed
space, or floor, ceiling, wall or combustible
construction. See FIG. 5.
b) Factory Built –Factory built chimneys are
generally stainless steel, insulated, multi-wall
pipes. Chimney must be listed to UL103 and
carry a rating of “HT” (High Temperature). The
top of the chimney must be at least three 3 feet
above the roof and be at least two 2 feet higher
than any point of the roof within ten feet –See
FIG. 6. A factory-built chimney must be
installed to the manufacturer’s specs.
If you have any questions regarding venting your
furnace, request a copy of the National Fire
Protection Association’s (NFPA) Publication 211
[Standard for Chimneys, Fireplaces, Vents &
Solid Fuel-based Appliances].
National Fire Protection Association
1 Battery March Park, Quincy MA 02169-7471,
1-617-770-3000 or online at www.nfpa.org.
NOTE:
This furnace must be connected to a minimum 6”
listed Type HT (High Temp) appliance-type chimney
or a code-compliant tile-lined masonry chimney.
Connection to a chimney flue serving another
appliance is prohibited.
FIG. 5
FIG. 6

DAKA 521FB Manual Page 13 of 32 January 2009
Rev. 2, June 2012
VIII. PLANNING YOUR INSTALLATION
FIG. 7
Supplementary/
Add-On
Installation
GENERAL INFORMATION
This furnace model is designed for a conventional up flow residential central force air heating
system. It may be installed as a SUPPLEMENTARY/ADD-ON or CENTRAL FURNACE APPLICATION.
It is designed to operate with a maximum warm air duct pressure of 0.2” water column and a maximum warm air
duct temperature of 250° degrees F. The warm air supply duct system must be constructed of materials with a
minimum temperature rating of 250° degrees F. Plenums installed to the furnace must be constructed of metal.
Do not use flexible pipe.
IMPORTANT: WHETHER INSTALLED AS A SUPPLEMENTARY/ADD-ON OR CENTRAL
FURNACE, INSTALLATION OF A COLD AIR RETURN LINE IS MANDATORY.
NOTE: Any time you increase the air flow, we recommend that you increase the size of the
outlets and the cold air return line.
D. SUPPLEMENTARY/ADD-ON FURNACE APPLICATION
When installed as a Supplementary/Add-On furnace, this DAKA furnace model is designed to work in conjunction
with a conventional up flow residential central forced air heating system. See FIG. 7.
Air can be provided to the DAKA furnace through the same cold air return line that is used by the primary furnace.
This will require installation of an air line between the cold air filter box and the cold air return line of the primary
furnace.
NOTE: When used as a Supplementary/Add-On furnace, confirm that your primary furnace is capable of running
at an external static pressure greater than 0.2” W.C. This information should be found on the primary furnace
nameplate.
It can be connected in parallel to a conventional primary furnace system. Using present ductwork, the DAKA
supplementary furnace system & blower lifts the warm air from the wood-burning furnace into the plenum of the
primary furnace for distribution by the primary furnace blower. The heat produced by the wood-burning furnace
should be able to keep the room temperature above that of the setting of the primary furnace wall thermostat.
This will keep the primary furnace from burning any gas, oil, or electricity beyond what is required to run the
primary distribution blower. Should the wood fire fail to provide sufficient heat, the primary furnace will begin
operating as usual.
When used as a supplementary/Add-On furnace, a fixed back-draft damper may be required in the 8” warm duct
pipes from the DAKA furnace. They also may be needed in the plenum of the existing primary furnace.
Installation of these back-draft dampers is to prevent overheating. We recommend that once the units are
operating that both units be monitored to make sure that neither is overheating.

DAKA 521FB Manual Page 14 of 32 January 2009
Rev. 2, June 2012
VIII. PLANNING YOUR INSTALLATION
E. CENTRAL FURNACE APPLICATION
When installed with its own plenum and ductwork, the furnace will operate as a freestanding Central
furnace. See FIG. 8.
The 550-cfm blower provided is often sufficient to provide air distribution for smaller homes with short
duct runs. A second optional 550-cfm blower (DAKA #273), or a large side-mounted multi-speed
blower & filter box (DAKA #218), may be required for larger homes with longer ductwork (available
online at www.dakacorp.com).
CAUTION: DO NOT USE AS A FREE-STANDING RADIANT HEATER.
NOTE: A cold air return line must be installed between the cold air return filter box and the rooms
being serviced by the warm air outputs of the DAKA furnace.
FIG. 8

DAKA 521FB Manual Page 15 of 32 January 2009
Rev. 2, June 2012
IX. ASSEMBLY INSTRUCTIONS
INSTALL FIRE DOOR
1. Attach fire door hinge to front of furnace.
See FIG. 9. Position hinge against furnace
with hinge pinhole closest to door opening.
When viewing hinge bracket from top, make
sure that the notched corner is facing away
from door opening.
2. Insert two ¼” hex bolts through hinge
bracket and holes located just to the right of
the door opening. Place washer and nut on
bolt from INSIDE furnace. NOTE: ¼” nut
that is used is a lock-nut and will require
that you use an open-end wrench to hold
the nut while turning the bolt with socket
driver on exterior. Center bolts in slotted
holes to start with. Tighten bolts enough to
hold bracket in place with fire door installed.
3. Install fire door onto hinge bracket. See
FIG. 10. Insert hinge pin from top down.
NOTE: Rotate door handle
counterclockwise to secure door in the
closed position.
4. With fire door installed, check fire door for
proper fit –doorframe should hit center of
rope gasket. If door doesn’t fit properly
(e.g., cast iron door hits door frame rather
than gasket), note location of problem and
then remove fire door. With fire door
removed, adjust hinge bracket location.
The holes in the hinge bracket are slotted
vertically for up and down adjustment. The
holes in the furnace are slotted horizontally
for left to right adjustment. Once the
proper placement has been found,
tighten bolts securely to prevent hinge
from moving.
INSTALL ASH PAN & ASH DOOR
1. Insert thermal gasket between ash door and
ash pan front, making sure that silver foil
side of gasket is facing INWARD toward ash
pan.
2. Securely attach ash door to ash pan using
two (2) ¼” bolts and nuts provided. See
FIG. 11.
NOTE: Ash pan is open-ended scoop design
for easy emptying of ash pan.
FIG. 9
Fire door 
Fire Door
FIG. 10
Ash Pan
FIG. 11

DAKA 521FB Manual Page 16 of 32 January 2009
Rev. 2, June 2012
IX. ASSEMBLY INSTRUCTIONS
Cast Iron Grate 
INSTALL FIRE BRICK
With everything removed from inside firebox,
install firebrick.
1. To install firebrick, hold firebrick in standing
position and angle top of firebrick toward
outside wall. Slip top edge of firebrick under
retaining angle. Stand firebrick up so bottom of
brick sits evenly on support rail.
2. Center rear firebrick (3) across back of
firebox. Insert sidewall firebrick (5 ea) at front
of furnace. As more are inserted, push brick as
far back as possible towards rear of furnace.
NOTE: There will be a small gap in each back
corner. This is normal and will not adversely
affect operation.
INSTALL CAST IRON GRATE
With reinforcement ribs facing down, insert
grate through fire door opening. Grate must be
held at a 45° degree angle as shown in FIG. 12.
Place one side edge down on support rail.
Drop other side down. Grate should lie flat on
both side support rails.
INSTALL AUTOMATIC DAMPER CONTROL
Remove Automatic Damper Control from
protective wrapping. Remove ¼” bolt and ¼”
nut that were installed in one corner of damper
control for shipping purposes only.
Attach Automatic Damper Control assembly to
front of furnace below the fire door opening with
six (6) No. 12 x ½” screws. Install top corner
screws first. Do not completely tighten until all
six screws have been inserted into holes.
NOTE: To ease installation of screws, use one
drop of motor oil on each screw before
installing. Use a 5/16” nut driver or a 5/16”
socket to install screws. TIGHTEN FIRMLY.
See FIG. 13.
Auto Damper
FIG.
FIG. 12
Grate 
FIG. 13
Auto Damper
Control 

DAKA 521FB Manual Page 17 of 32 January 2009
Rev. 2, June 2012
IX. ASSEMBLY INSTRUCTIONS
INSTALL BLOWER
NOTE: For Add-On furnace installation, do
NOT remove the back-draft damper plate.
For Central Furnace installation, back-draft
damper plate may be removed. (It is located
inside the blower inlet on the right hand side of
back of furnace. Break wire nut to remove).
Install 550-cfm blower over inlet on right hand
side of back of furnace using four (4) No. 12 x
½” screws. See FIG. 14.
CAUTION: Handle blower by the housing unit.
DO NOT REACH INSIDE IMPELLER CAVITY.
INSTALL AIR JACKET PANELS
Furnace is shipped with air jacket panels
installed. If loose or removed during
installation, re-install as follows:
1. Install bottom edge of side panel into
channel on bottom support rail. Working
from the bottom up, press side panel tightly
against firebox. See FIG. 15.
2. Install top air jacket from back to front
making sure air jacket lip goes OVER the
outside of side panels (shoebox style fit).
NOTE: To ease top over sides, insert a
putty knife under top lip and pry lip outward
over side panel. See FIG. 17.
INSTALL SWING PLATE
Open fire door and carefully feel for two (2)
steel hooks above door opening. With bent
edge facing inward, hang swing plate from
hooks. See FIG. 15.
FIG. 14
Blower 
FIG. 15

DAKA 521FB Manual Page 18 of 32 January 2009
Rev. 2, June 2012
IX. ASSEMBLY INSTRUCTIONS
MOUNT JUNCTION BOX, INSTALL FAN CONTROL,
INSTALL CONDUIT WITH PRE-RUN WIRES, & WIRING
INSTALL FAN CONTROL ASSEMBLY
Junction Box and Conduit (FIG. 16):
1. Remove cover plate from junction box.
2. Mount junction box using two (2) No. 12 x
½” screws onto left side of furnace in outer
pre-punched holes.
NOTE: Screws go in upper left and bottom
right slotted corners.
3. Remove one knockout plug from bottom
and one knockout plug from top or from
whichever side your power supply will be
entering.
4. Place a conduit connector on each end of
the flexible conduit.
5. Insert one connector in the bottom hole of
the junction box located on side of furnace.
6. Attach the other connector to the junction
box on blower motor.
Snap Disc Fan Control: (FIG. 17)
1. Mount Snap Disc Fan Control using two
(2) No. 12 x ½” screws onto left side of
furnace in inner pre-punched holes
located within the junction box.
NOTE: Make sure Fan Control is flush
against furnace air jacket panel.
FIG. 16
Junction Box &
Cover
FIG. 17
Outside Wiring

DAKA 521FB Manual Page 19 of 32 January 2009
Rev. 2, June 2012
IX. ASSEMBLY INSTRUCTIONS
WIRING INSTRUCTIONS
WARNING: Disconnect all power before
making electrical connection.
Power Supply Connections
1. Using an approved conduit and connector,
bring a 3-wire 120V AC 15-amp minimum
electrical service to the Junction Box.
2. Use minimum No. 14 AWG or larger wires,
rated for at least 105C (not provided).
NOTE: Power connections should be made by
a qualified installer to comply with The National
Fire Protection Association (NFPA) Standard
No. 70 (National Electric Code) and all local
codes and regulations.
Blower Junction Box Wiring:
1. Inside the blower junction box, connect
wires with two blue wire nuts as follows: a)
Black wire to one blue wire; b) White wire to
other blue wire. Blower motor operates in
one direction only & is not reversible.
2. Tuck the wires into blower junction box.
3. Replace blower junction box cover.
Fan Control Wiring:
1. Attach one of the crimp terminals to black
(hot) power supply wire.
2. Attach the other crimp terminal to one end
of one blue wire coming from blower.
3. Attach the two crimp terminals to each side
of the Snap Disc Fan Control.
4. Connect other blue wire to white wire
supplying power to the unit.
5. Connect green ground wires together.
6. Check all connections for tightness and
electrical safety.
7. Coil all wires within junction box.
8. Install 4” square Junction box cover plate.
FIG. 18

DAKA 521FB Manual Page 20 of 32 January 2009
Rev. 2, June 2012
IX. ASSEMBLY INSTRUCTIONS
COLD AIR RETURN FILTER BOX
ASSEMBLY & INSTALLATION
1. Using the sheet metal screws provided (Key 6) first attach the bottom panel (Key 2) to side
panel A (Key 3)
2. Next, attach side panel B (Key 4) and side panel C (Key 5) to bottom panel (Key 2).
3. With blower and wiring already installed on DAKA furnace, the next step is to loosen, but not
remove, all four screws holding the fan hole cover plate. (See FIG. 2).
4. Remove air jacket top and right side air jacket panel from DAKA furnace.
5. Take the partially assembled filter box and slide it into position. Once in position, slide outer
flange on panel A (Key 3) under the fan hole cover plate. Retighten the four screws holding
the fan hole cover plate. Once these screws are tightened, they will hold the left side of the
filter box in position.
6. Install top panel of filter box to all side panels.
7. Reinstall right air jacket side panel, making sure back edge of air jacket panel overlaps outer
flange on panel C. Once air jacket side panel is in position, it will hold the right side of the
filter box in position.
8. Place air jacket top back onto DAKA furnace.
9. INSTALLATION OF A COLD AIR RETURN LINE IS MANDATORY:
−Minimum size is 13” x 13” or 170 square inches.
10. Furnace Filter: Size 14 x 20 x 1 fiberglass filter (side may be cut to fit width of filter box).