Central Boiler FORGE 1500 User manual

OWNER’S MANUAL
FORGE 1500
FORGE 3500
SAVE THESE
INSTRUCTIONS
(p/n 9000578 - REV. A) - 12-DEC-2017
WARNING: If the information in this manual is not followed exactly, a re or explosion may result causing
property damage, personal injury or loss of life.
– Do not store or use gasoline or other ammable vapors and liquids in the vicinity of this or any other appliance.
– WHAT TO DO IF YOU SMELL GAS
• Do not try to light any appliance.
• Do not touch any electrical switch.
• Immediately call your gas supplier. Follow the supplier’s instructions.
• If you cannot reach your gas supplier, call the re department.
– Installation and service must be performed by a qualied installer, service agency or the gas supplier.
Portland
Oregon USA
OMNI-Test Laboratories, Inc.
Tested &
Listed By
US
OUTDOOR COAL FURNACE
0117CB037S

Central Boiler, Inc. • 20502 160th Street • Greenbush, MN 56726
www.CentralBoiler.com
For parts and accessories, service or repairs, call your authorized Central Boiler dealer or heating contractor. Record
the information below for future reference.
Model Serial Number Installation Date
Dealership Name Phone Number
Owner Name
e Forge outdoor hydronic heater by Central Boiler is listed by OMNI-Test Laboratories to the applicable portions of the following
standards: UL 2523-2013 Solid Fuel-Fired Hydronic Heating Appliances, Water Heaters, and Boilers, CAN/CSA-B366.1-11 (R2015)
Solid Fuel-Fired Central Heating Appliance. Certied to add to an existing heating system.
e Forge includes two 4-foot stainless steel insulated chimney sections (6" in diameter, p/n 6500004). Use only stainless steel solid
fuel chimneys specied by Central Boiler.
Adjust for ue draft between -0.05 and -0.08 in. WC (-12.45 Pa and -19.91 Pa). Maximum draft is marked on nameplate.
Forge 1500 - Water Capacity: 150 gal. - Weight: 1,750 lbs
Forge 3500 - Water Capacity: 210 gal. - Weight: 2,150 lbs
French Owner's Manual and decal set available upon request from your dealer
(Manuel d'installation en français et décalcomanies disponible sur demande auprès de votre revendeur)
• Any person(s) operating a hydronic heater must comply with all applicable laws, including but not limited to local ordinances.
• Improper use or failure to maintain the hydronic heater may cause nuisance conditions. e person(s) operating a hydronic heater is/
are responsible for operation in a manner that does not create a nuisance condition. Meeting the setback distance and stack height
recommendations from the manufacturer and requirements in applicable State and local regulations may not always be adequate to prevent
nuisance conditions in some areas due to terrain or other factors.
• Operating an outdoor furnace may not be suitable to some individuals' abilities or lifestyles. Be sure to review the Owner's Manual for the
appliance with your dealer.
OUTDOOR COAL FURNACE

Contents
How to Use This Guide
e guide is divided into sections
to help with the operation and
maintenance of the outdoor furnace.
If questions arise that are not
answered with this manual, consult
with your authorized Central Boiler
dealer.
CENTRAL BOILER ONLINE RESOURCES............................................................ iv
Terms and Symbols............................................................................1
Glossary and Industry Terminology ..............................................................2
Foundation...................................................................................3
Access to Ports on Outdoor Furnace.................................................... 4
Ground Rod Kit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Furnace Installation - Connecting to Your Existing System ................................ 5
Chimney Recommendations.......................................................... 8
Important Precautionary Information ................................................. 9
Helpful Tips....................................................................... 11
Understanding Coal ................................................................ 12
Anthracite ..................................................................................12
Bituminous..................................................................................13
Lignite......................................................................................13
Operating Instructions ............................................................. 14
FireStar Combustion Controller .................................................................14
Firebox Door Opening Procedure................................................................14
Maintaining the Ash Bed ......................................................................15
Cold Start Firing..............................................................................15
Adding Heat Load ............................................................................19
Loading Frequency ...........................................................................19
About Clinkers ...............................................................................24
Dump to Empty Procedure.....................................................................25
Dump and Reload Procedure...................................................................25
Ash Cleanout ................................................................................26
Maintenance...................................................................... 28
Control Locations.............................................................................29
ROUTINE MAINTENANCE.......................................................................29
WATER QUALITY AND MAINTENANCE .................................................. 40
Water Test Kits and Test Results.................................................................40
Testing Supply Water .........................................................................41
Corrosion Inhibitor Plus™ and InitialTreatment ...................................................41
Testing Treated Water in the Outdoor Furnace.....................................................42
SYSTEM MAINTENANCE .......................................................................43
POST HEATING SEASON MAINTENANCE...........................................................44
Flushing the System ..........................................................................44
SERVICEABLE ITEMS ................................................................ 46
FIREBOX DOOR HINGE / LATCH BEARING ADJUSTMENT..............................................46
FIREBOX DOOR SEAL ..........................................................................47
ASH REMOVAL DOOR SEAL .....................................................................48
THERMOCOUPLE .............................................................................49
TROUBLESHOOTING ................................................................ 50
GENERAL INFORMATION............................................................. 57
Coal Sizes ...................................................................................57
Decals. .....................................................................................58
WIRING DIAGRAM.................................................................. 59

FORGE OUTDOOR COAL FURNACE • OWNER'S MANUAL
CENTRAL BOILER ONLINE RESOURCES
Enter CentralBoiler.com in your browser or scan the code using any QR code reader app on your smartphone to access Central
Boiler's library of information to help with installation, operation and maintenance of your Central Boiler outdoor furnace.
Detailed Furnace Installation Variations - http://www.CentralBoiler.com - go to Explore > Furnace Installation
View and/or download PDFs to assist in installation of your outdoor furnace. Information and examples
regarding pumps, foundations, chimneys and support structures, ermoPEX piping, and example congurations
for a variety of heating congurations.
Product Service Videos - http://www.CentralBoiler.com - go to Explore > Videos
Push-t Fittings
Central Boiler's push-t ttings make conguring and connecting your
heating system easy and quick.
Performing a Water Test
Testing and maintaining the water in your system is critical for the
operation and longevity of your heating system.
INSTALLATIONS IN MASSACHUSETTS:
1. All installation components must be products approved in the Commonwealth of Massachusetts by the Gas and Plumbing Board.
2. e maximum run of tubing from the water heater to a fan coil is 50 linear feet.
3. Persons operating this hydronic heater are responsible for operation of the hydronic heater so as not to cause a condition of air pollution as
dened in 310 CMR 7.01(1).
Videos to supplement the Owner's Manual are available at
www.youtube.com/centralboilerinc
Watch tips on initial startup, testing system water and more.

1
FORGE OUTDOOR COAL FURNACE • OWNER'S MANUAL
Terms and Symbols
e outdoor furnace and this installation guide use the following terms and
symbols to bring attention to the presence of hazards of various risk levels and
important information concerning the use and maintenance of the outdoor
furnace.
This symbol and text indicate an imminently hazardous situation which, if ignored,
will result in death or serious injury.
This symbol and text indicate the presence of a hazard which can cause severe personal
injury or death to an operator or bystander, or substantial property damage if ignored.
CAUTION
This symbol and text indicate the presence of a hazard which can cause minor personal
injury or property damage if ignored.
NOTE: Indicates supplementary information worthy of particular attention relating
to installation, operation, or maintenance of the outdoor furnace but is not related to a
hazardous condition.
Be sure to follow all instructions and related precautions as they are meant for
your safety and protection. Store this manual in a readily accessible location for
future reference.
Forge 1500 Measurements
A B C D E F G IH
cm
in.
- Measurement (G) includes two 4 ft (1.2 m) chimney sections.
- All measurements are approximate
- Measurement (F) is from firebox door to chimney inspection cover.
Forge 3500 Measurements
A B C D E F G IH
cm
in.
© 2016 Central Boiler
DH
E
B
A
G
I
F
C
43 72 53 49 53 3 2669 144
109 183 135 124 135 8 66175 366
47 79 63 51 64 3 2679 151
119 201 160 130 163 8 66201 384

2FORGE OUTDOOR COAL FURNACE • OWNER'S MANUAL
Glossary and Industry Terminology
Several terms and words used throughout this owner's manual are unique to
the coal-burning industry:
Clinker
A mass of fused ash. A clinker is typically very hard and may have the
appearance of lava rock or melted glass (see About Clinkers section for more).
NOTE: Coke can sometimes look like a clinker and vice versa. The coke will typically be less
dense and will burn over time (a clinker will not).
Coke
Coal that has had all its volatiles burned o with only carbon remaining.
Fines
Coal that is typically smaller than barley size (see the anthracite size chart in the
General Information section).
Flashback
A sudden ignition of combustible gases. Flashback typically happens when
combustible gases, already at the temperature of ignition but starved of oxygen,
are suddenly introduced to an oxygen-rich environment. For this owner's
manual, it refers to an instance with the rebox door or ash door being opened
when combustible gases are present, or when breaking up a burning coal bed.
Under Air
e main combustion air supply. Under air is the air that is introduced under
the burn grates and forced through the fuel load.
Pu Back
Pu back is similar to ashback, but sometimes happens when the outdoor
furnace starts up after being idle. e gases ignite and a large plume of smoke
is emitted out of the chimney. Pu back typically happens when the outdoor
furnace is loaded with fresh coal when there is little or no call for heat, allowing
volatile gases to build up.
Run of Mine
Coal that has been extracted from the earth but has not been sorted and sized
in any way.
Over Air
Over air is additional air that is introduced into the rebox above the burning
coals. Its purpose is to provide supplementary air to allow the volatiles and
smoke to be burned o. is feature is especially useful when burning coal
such as bituminous that smokes a lot or has a higher concentrations of volatiles.
Volatiles
Combustible gases released when coal is heated.

3
FORGE OUTDOOR COAL FURNACE • OWNER'S MANUAL
Foundation
e outdoor furnace may be installed directly on stable, level ground without
the necessity of a foundation, although installing the outdoor furnace on a
foundation oers many advantages. e outdoor furnace is less likely to move
due to frost heaving. A foundation keeps the area directly around the outdoor
furnace free of standing water and can help to keep unwanted pests out. It can
also raise the furnace up to provide a more comfortable height of the rebox
door opening.
If the ground is unstable, one option is to use patio blocks under the perimeter
of the base. Another option is to pour a concrete foundation.
To install the outdoor furnace on a concrete foundation, refer to the illustration
for dimensions and for the location of the hollowed-out area for each model. A
4" to 6" (10 to 15 cm) thick concrete slab works well; however, a thicker slab
may be used to obtain the desired door opening height.
If the area for the concrete slab is unstable and/or aected by frost heaving,
consider installing 2" closed-cell insulation beneath the front portion of the
slab and under the area of the ground used for walking.
CAUTION
Do not use any combustible materials for the foundation.
NOTE: The installation surface or foundation must be noncombustible. The hot supply and
return lines must also be protected from possible exposure to sunlight, re or physical
damage that may be caused by an occurrence outside the outdoor furnace enclosure.
Foundations may consist of concrete, crushed rock or patio blocks.
Do not use any combustible
materials for the foundation.
CAUTION
© 2016 Central Boiler
Outdoor furnace must be installed on a noncombustible surface or foundation that incorporates an enclosure
that will prevent supply and return lines from possible exposure to sunlight, fire, or physical damage that may be
caused by an occurrence outside the outdoor furnace enclosure. Foundation may consist of concrete, crushed
rock, or patio blocks.
44 in. (1.12 m) from the back
48 in. (1.22 m) from the front
12 in. (0.3 m) from the sides
18 in. (0.46 m) from the chimney
inspection cover
Do not store wood or other
combustible material within installation
clearances.
Installation Clearances to Combustibles
56"
(142 cm)
Forge 1500
(Foundation Optional)
46"
(117 cm)
Front
66"
(168 cm)
Forge 3500
(Foundation Optional)
50"
(127 cm)
8"
(20 cm)
13"
(33 cm)
Front
26"
(66 cm)
8"
(20 cm)
13"
(33 cm)
26"
(66 cm)

4FORGE OUTDOOR COAL FURNACE • OWNER'S MANUAL
Access to Ports on Outdoor Furnace
Ports are provided that allow mounting circulation pumps on the outdoor
furnace. Refer to the illustrations in this section for proper supply and return
line and pump installations for your model.
NOTE: The Installation Guide provides more information on pump selection. For even more
detailed information, see the Hydronic Component Selection Guide (p/n 2482), available
from your Central Boiler dealer.
556
224
5000018
5800006
388
534
388
118
118
118
180
6054
5926
133
1330
PEX Pipe
3/4" Return Side View
2 - Pump Parts Lists*
For 3/4" (1" PEX) system
198
296
6 118 Close Nipple, 3/4"
2 133 Tee NPT, 3/4"
2 388 Hex Bushing,
1-1/4" x 3/4"
1 5800004 007 Pump
2 180 Bushing, 3/4" x 1/8"
2 198 Ball Valve, 3/4"
2 224 Isolation Flange Kit,
3/4"
2 296 Swing Check Valve,
3/4"
2 556 Power Supply Cord
4 1330 MPT to PEX, 3/4" x 1"
4 5926 Stainless Steel Clamp
Crimp Ring, 1"
2 6054 Temperature Gauge
1 6593 Grounding Rod Kit
1 5000018 Nipple, 3/4" x 3"
1 534 Nipple, 3/4" x 7"
1 5800006 009 Pump
*Parts and accessories sold separately.
Pump size may vary.
For illustration purposes only
5800004
556 171
224
5000018
388
388
118
118
118
180
6054
5926
133
1330
PEX Pipe
3/4" Return Side View
1 - Pump Parts Lists*
For 3/4" (1" PEX) system
198
296
3 118 Close Nipple, 3/4"
1 133 Tee NPT, 3/4"
1 388 Hex Bushing,
1-1/4" x 3/4"
1 171 007 Pump
1 180 Bushing, 3/4" x 1/8"
1 198 Ball Valve, 3/4"
2 224 Isolation Flange, 3/4"
1 296 Swing Check Valve,
3/4"
1 556 Power Supply Cord
1 1330 MPT to PEX, 3/4" x 1"
2 5926 Stainless Steel Clamp
Crimp Ring, 1"
1 6054 Temperature Gauge
1 6593 Grounding Rod Kit
1 5000018 Nipple, 3/4" x 3"
*Parts and accessories sold separately.
Pump size may vary.
For illustration purposes only
Forge 3500 Models – 2-Pump Conguration*Forge 1500 Models – 1-Pump Conguration*

5
FORGE OUTDOOR COAL FURNACE • OWNER'S MANUAL
Ground Rod Kit
e outdoor furnace must be electrically bonded to ground in accordance with
the requirements of the authority having jurisdiction or, in absence of such
requirements, with the National Electrical Code, ANSI/NFPA 70 and/or the
Canadian Electrical Code Part 1, CSA C22.1 Electrical Code.
Install a Ground Rod Kit (p/n 6593) and connect it to the outdoor furnace.
1. In the water line trench near the outdoor furnace, drive the ground rod
into the ground until the top of the ground rod is below the ground
surface.
2. Route the ground wire from the ground rod under the outdoor furnace
base and over to the frame of the outdoor furnace.
3. Secure the ground terminal with a cap screw (1/4" x 3/4"), star washer
and nut. Secure the ground wire to the terminal; then secure the ground
wire to the ground rod with the clamp. Tighten all hardware securely.
NOTE: A hole for the ground terminal has been pre-punched in the outdoor furnace base
near the pumps.
Furnace Installation - Connecting to Your Existing System
A common installation is to connect the outdoor furnace to an existing water
heater and then to an existing forced air system. A water-to-air heat exchanger
is mounted in the plenum or duct work of the existing furnace. Heated water
from the outdoor furnace either continuously ows through the water-to-air
heat exchanger or is diverted through a 3-way zone valve. When the thermostat
senses the need for heat, the fan on the existing furnace forces air through the
heat exchanger, transferring heat throughout the existing ductwork.
NOTE: There are numerous ways to connect to your heating system. Refer to the Central
Boiler Outdoor Furnace Installation Guide for other installations.
Detailed Furnace Installation Variations
Visit CentralBoiler.com to access
a library of detailed illustrations
for connecting to a wide variety of
existing heating systems and for
other heating options.

6FORGE OUTDOOR COAL FURNACE • OWNER'S MANUAL
H
C
M
R
Hot Supply
Water-to-Water
Heat Exchanger
Bypass Line
Thermostatic
Mixing Valve
This horizontal assembly
must not exceed a height
of 4 inches (10 cm) above top
of water heater.
Existing
Water
Heater
1"
Central
PEX®
Optional Bypass
Valve
Heat
Exchanger
Plenum
Existing
Forced Air
Furnace
For illustration purposes only,
water heater styles may vary.
NOTE
A pump must be installed in the hot
supply line between the outdoor furnace
and thermostatic valve. Outdoor furnace
water temperature setpoint should be
set at 185˚F (85˚C) minimum.
NOTE
Installer must comply with all
applicable codes and regulations.
NOTE
Any electrical installation should
be done by a qualified installer
in accordance with applicable
codes.
NOTE: A certified electrician must
do the electrical installation.
Typical Installation
Connecting to Water Heater and Forced Air Furnace
© 2014 Central Boiler
Hot Supply from Pump
on Outdoor Furnace
Return to Outdoor Furnace
Optional Thermostatic Valve
To Thermal
Storage Tank
To Heating
System
From Heating
System
Hot Supply from Pump
on Outdoor Furnace
Return to
Outdoor Furnace
Remote
Thermal
Storage
Tank
For illustration purposes only;
system components may vary.
NOTE
Installer must comply with all
applicable codes and regulations.
Optional
Thermostatic
Valve
Remote Thermal Storage Installation
Connecting to Remote Thermal Storage Tank

7
FORGE OUTDOOR COAL FURNACE • OWNER'S MANUAL
OUTDOOR COAL FURNACE
BEST BURN PRACTICES
1. Read and follow all operating instructions supplied
by the manufacturer.
2. FUEL USED: Only those listed fuels recommended
by the manufacturer of your unit. Never use the
following: trash, plastics, gasoline, rubber, naphtha,
household garbage, material treated with petroleum
products (particle board, railroad ties and pressure
treated wood), leaves, paper products, and
cardboard.
3. LOADING FUEL: For a more efficient burn, pay
careful attention to loading times and amounts.
Follow the manufacturer’s written instructions for
recommended loading times and amounts.
4. STARTERS: Do not use lighter fluids, gasoline, or
chemicals.
5. CHIMNEY RECOMMENDATIONS: In higher
populated areas, extend the chimney to a height
above the roofs of surrounding buildings.
6. Always remember to comply with all applicable state
and local codes.
Be considerate of neighbors when operating your
furnace. If you use your furnace in the summer months,
be certain your chimney exhaust is not adversely
affecting neighbors with open windows.

8FORGE OUTDOOR COAL FURNACE • OWNER'S MANUAL
Chimney Recommendations
In higher populated areas, extend the chimney to a height
above the roofs of surrounding buildings. Use Central
Boiler Chimney Extensions when extending the chimney.
When only the standard eight feet (2.4 m) of chimney are
used, the sections must be secured at the connection joint
with four (4) screws to stabilize the extension.
If extensions are added to the standard eight feet
(2.4m) of chimney, the chimney should be reinforced
appropriately. e illustration shows chimney support
recommendations when three or more sections are used.
When adding sections of chimney, make sure that there
is nothing within the fall zone of the chimney that could
be damaged. If something is located within the fall zone
and cannot be removed, guy wires or braces may need
to be installed to prevent a falling chimney from causing
damage.
NOTE: If more than three 4-foot (1.2-m) sections of chimney are used, a
support (e.g., a pole, pipe or other structural support) may be installed
from the ground that can withstand wind. Other reinforcement
recommendations are shown.
NOTE: For chimney extensions or chimney replacement, use only
genuine Central Boiler chimney components. Parts are available
from an authorized Central Boiler dealer.
e installation of a spark arrester is recommended,
particularly where there are dry conditions or where
there is combustible material near the unit, unless the
installation of a spark arrester is prohibited by local
requirements. Use common sense to avoid potential
res, including exercising caution when disposing of
ash, cleaning and refueling. Keep all highly combustible
materials (e.g., gasoline, propane, leaves, pine needles,
etc.) away from an operating unit at all times. Take special
precautions in windy conditions.
NOTE: You may need to increase the chimney height if conditions
occur that force exhaust to low levels.
Chimney Reinforcement Recommendations
Chimney
Guy-Wire
Band Kit
(p/n 778)
Fall Zone
If objects are placed in the fall zone of the chimney, a
Chimney Guy-Wire Band Kit (p/n 778) or additional bracing
is recommended.
6" Chimney Locking
Band (p/n 6500011)
Chimney
Base
Bracket
(p/n 4519)
6" Chimney Extension (p/n 6500004)
Additional bracing may be necessary in
certain areas such as those subject to severe
weather, winds, freezing rain, etc.
Inspect all bracing bi-annually for integrity.
•
•
NOTE
Five or More Sections
When five or more sections of
chimney are being used, a Chimney
Base Bracket Kit (p/n 4519) and a
Chimney Attachment Ring (p/n 774)
are recommended.
Chimney Attachment Ring (p/n 774)
Must be located directly below Chimney
Locking Band to reduce stress on the
joint.
Two 1" electrical
conduit sections
(not supplied)
Two 3/4"electrical
conduit sections
(not supplied)
Three or Four Sections
When three or four sections of
chimney are being used, aChimney
Base Bracket Kit (p/n 4519) is
recommended.

9
FORGE OUTDOOR COAL FURNACE • OWNER'S MANUAL
Important Precautionary Information
Be sure to read carefully and understand these precautions before, during and after the installation, operation and
maintenance of the furnace.
NOTE: All operations must be in accordance with local and state
codes which may dier from the information in this manual.
NOTE: Be considerate of your neighbors. Some types of coal will
smoke quite a bit and emit a pungent odor. Try dierent types
of coal, adjusting your settings, and learning dierent load
techniques to minimize the amount of smoke generated.
NOTE: Some types of coal (in particular, coal with very high sulfur
and impurity content) will always produce visible smoke. With this
coal, there will always be some smoke present regardless of the
settings used with the outdoor furnace.
CAUTION
This outdoor furnace is not intended to be the only source of
heat. In the event of a prolonged power failure, a generator
may be used to prevent lines from freezing. Should the outdoor
furnace be left unattended, run out of fuel or require service, an
alternate heating source in the building being heated should
be in place to prevent damage caused by freezing.
The outdoor furnace vent cap must t loosely on the vent
opening. Do not force the cap down or try to seal it tightly onto
theventpipe.Do notextendorrestrict thevent pipe oropening.
DO NOT ALLOW THE OUTDOOR FURNACE TO BE PRESSURIZED.
Be sure the outdoor furnace is lled with water before ring.
Never re the outdoor furnace when the water level is more
than 1" (2.5 cm) below the FULL mark on the sight gauge.
Corrosion Inhibitor Plus™ must be added before the initial ll
(see Water Quality and Maintenance).
Disconnect the electrical power to the outdoor furnace before
replacing an electrical component.
Do not attempt service inside the electrical control panel
without rst disconnecting the electrical power at the main
power source.
NOTE: Any electrical installation should be done by a qualied
installer in accordance with applicable codes.
Allow the outdoor furnace to thoroughly cool and completely
clean out the rebox before draining water from the outdoor
furnace. If the water in the outdoor furnace ever boils, be sure
to check the water level and restore to full. If water is added,
the proper level of Corrosion Inhibitor Plus™ (p/n 1650) must be
maintained.
When cleaning the outdoor furnace, be careful not to spill any
coals.
ALWAYS store ash in a covered non-combustible container.
Do not allow combustible materials (straw, hay or wood) near
the outdoor furnace. Keep the perimeter of the outdoor furnace
clear and clean.
Keep children away from the outdoor furnace.

10 FORGE OUTDOOR COAL FURNACE • OWNER'S MANUAL
DO NOT touch the outdoor furnace during operation.
For re safety, keep all combustible materials at least six feet
(two meters) away from the outdoor furnace, especially around
the door area. Debris of wood chips and other combustibles in
the area may be easily ignited if a hot coal is spilled out of the
rebox and left unnoticed.
To reduce the risk of ashback, the door opening procedure
outlined in this owner's manual should be followed whenever
the rebox door or ash removal door is opened, even if the
outdoor furnace has been shut down for an extended period of
time.
The rebox door must be closed and latched at all times except
when lling the rebox. Leaving the rebox door open may
lead to a runaway re. In the event of a runaway re, close the
rebox door. In the event of a chimney or soot re, close the
rebox door and make sure power is o to the outdoor furnace.
The ash removal door must be closed and secured at all times
except when removing ash or a runaway re may result. The
ash removal door should never be opened when the outdoor
furnace is in idle or standby mode. Combustible gases can
collect and ignite when exposed to air, causing a ashback.
All covers must be maintained at all times except during
maintenance, inspection and service.
Do not burn trash, plastics, gasoline, rubber, naphtha,
household garbage, material treated with petroleum products
(particle board, railroad ties and pressure treated wood),
leaves, paper products or cardboard.
NOTE: Do not use chemicals or uids to start the re. Use kindling
and seasoned wood to start an initial re.
NOTE: The use of wood in this outdoor furnace, except for the
purpose of igniting the coal, is prohibited by law.
NOTE: The sight gauge valve should always be closed, except when
checking water level. Water will automatically drain from the
sight gauge tube when the valve is closed. Remember that this
type of valve requires only 1/4 turn to open or close.
This heater is designed to burn coal. DO NOT BURN: any wood
that is not clean wood, unseasoned wood, garbage, tires, lawn
clippings, leaves, brush trimmings or general yard waste,
materials containing asbestos, materials containing lead,
mercury or other heavy toxic metals, materials containing
plastic,materialscontainingrubber, wastepetroleumproducts,
paints and paint thinners, asphalt products, chemicals, glossy
or colored paper, construction and demolition debris, plywood,
particleboard, salt water driftwood and other previously salt
water saturated materials, manure, animal carcasses and
asphalt products. Burning these materials may result in release
of toxic fumes or render the heater ineective and cause smoke.
NOTE: This outdoor furnace is not to be used with an automatic
stoker.
NOTE: Store coal properly. Keep coal where it will stay dry.
Some types of coal will soak up moisture which can aect burn
performance, create excessive smoke, and add moisture to the
exhaust which can create potential for corrosion.
NOTE: Do not store coal within the outdoor furnace installation
clearances or within the spaces required for fueling, ash removal
and other routine maintenance operations.
CAUTION
This outdoor furnace is not to be connected to a chimney ue
serving another appliance.
Sulfuric acid in the test kit is a corrosive acid. Handle carefully.
Carefully read and follow precautions on test chemical labels.
Keep test chemicals away from children. Safely dispose of tested
samples.

11
FORGE OUTDOOR COAL FURNACE • OWNER'S MANUAL
Helpful Tips
• Unlike anthracite, which is fairly consistent in its composition,
bituminous coal can vary greatly not just from one mine to another, but
from dierent portions of the same mine. Whenever getting a new load
of coal, pay close attention to the outdoor furnace when rst burning it
to determine whether or not adjustments can be made to the outdoor
furnace settings.
• Have a proper disposal plan for ash. If you have not burned coal before,
you might be surprised by the amount of ash. Some coal has an ash
content greater than 10% by weight. Have a proper disposal plan in place
and check with your local jurisdiction about proper disposal procedures.
• Coal ash is more corrosive than wood ash so moisture in the rebox and
ash collection areas should be kept to an absolute minimum. Use only coal
that has been kept out of the elements and is dry. Any wood burned in the
outdoor furnace should also be well-seasoned and dry.
• Do not allow ash to get clumped together in the rebox or in the ash
collection chamber.
• Record your load times, quantity of coal added, type of coal, coal size,
loading techniques and controller settings. ese can be helpful when
ne-tuning your outdoor furnace to achieve the most ecient and cleanest
possible burns.
• Perform the recommended preventative maintenance following the service
intervals. Regular maintenance and inspections can help extend the life of
your outdoor furnace and prevent high-cost repairs.
• An important part of outdoor furnace maintenance is controlling the
quality of the water in the outdoor furnace. Follow the recommended
procedures in the Water Quality and Maintenance section carefully.
Guidelines are provided for testing supply water, initial water treatment
and testing the water in the system once the outdoor furnace has been
operated.
• Contact the mine where you purchase coal and see if they have a coal
analysis available. Some mines will provide a coal analysis for free. From
a coal analysis you can learn percentages of moisture, Btu per pound, ash
content per pound, sulfur content, volatile percentages, and other useful
information which can help when adjusting the settings on your outdoor
furnace.
• Adjust the over air so there is just enough available in both duration and
volume to help burn the volatiles and smoke. Too much over air can dilute
the smoke instead of burn it. is will be evident by a signicantly lower
ue gas temperature.

12 FORGE OUTDOOR COAL FURNACE • OWNER'S MANUAL
Understanding Coal
Burning coal is a completely dierent experience than if you are used to burning
wood. First and foremost, there are many dierent types of coal. While wood
contains essentially the same Btu content per pound regardless of species, coal
varies greatly from type to type, not just in energy content per pound, but also in
volatile and sulfur content. Volatile content is used to describe the combustible
gases that are released when coal is heated up.
Because each type of coal burns dierently, each requires special attention when
handling and burning. ere a many types of coal available, but for heating
purposes, the most common types are: Anthracite, Bituminous (or Sub-
Bituminous), and Lignite.
Anthracite
Anthracite, sometimes referred to as hard coal, is the highest grade of coal. When
cleaned, it has a shiny black appearance similar to volcanic glass. It is extremely
hard, being very dicult to break by hand. When clean, anthracite will not
typically make marks if rubbed on paper.
If burning anthracite in the Central Boiler Forge Outdoor Coal Furnace, nut
sized coal is preferred.
Advantages of Anthracite
• Anthracite, by its nature, retains consistently similar characteristics, even
between dierent mines.
• e swell factor (the property of coal to swell and bind to other pieces
when heated) is almost nonexistent, so even when glowing red in a
outdoor furnace, anthracite coals can be easily stirred.
• Anthracite has the highest percentage of carbon content while having
low volatile and sulfur contents. Because of this, it burns nearly smoke
and odor free.
Disadvantages of Anthracite
ere are some unique characteristics of anthracite that make it not suitable for
all applications.
• e most noticeable characteristic of anthracite is that it is dicult to
light. Typically a deep bed of glowing wood coals has to be established
before any anthracite coal can be added to the re, and once burning,
a thick bed of anthracite must be maintained. If not, air holes will
form in the coal bed and the re will quickly go out.
• Anthracite burns best when all of the combustion air is brought up
through the coal bed. In comparison, bituminous coal requires some
over re air to burn the released volatiles.
Before You Start Operating Your
Forge Outdoor Coal Furnace
Be sure to read carefully and observe
all of the information in the entire
Owner's Manual.
If any questions arise that cannot
be answered by the information in
this manual, be sure to contact your
dealer.
Cleaned anthracite has a shiny black
appearance similar to volcanic glass.

13
FORGE OUTDOOR COAL FURNACE • OWNER'S MANUAL
• Anthracite does not idle very well; the more constant heat draw, the
better. During warmer months, it may be impossible to maintain an
anthracite re simply due to the extended periods of standby between
on and o cycles.
• Limited availability – anthracite is mostly mined in a few counties in
Pennsylvania and thus may be dicult to obtain in certain locations.
Bituminous
Bituminous is the grade of coal just below anthracite and is sometimes referred
to as soft coal. Like anthracite, bituminous coal is black but will have a more
dull color (although it can be shiny at times). It is typically easier to break apart
compared to anthracite and will make a mark like a charcoal pencil when rubbed
on paper. Compared to other types of coal, it is the most plentiful and readily
available in the United States. Because of its availability, bituminous is the most
likely to be burned in an outdoor coal furnace.
If burning bituminous coal in the Central Boiler Forge Outdoor Coal Furnace,
run of mine (to a degree) or sorted coal can be burned. e sizes of the largest
pieces of coal present in each load must be smaller than stove size, with nothing
larger than nut size preferred.
Unlike anthracite, bituminous coal can vary a lot in its Btu, moisture, sulfur, ash
and volatile content per pound. Because of this, certain additional precautions
need to be taken when burning bituminous.
• e higher volatile and sulfur content gives bituminous coal a distinct odor.
• Not only will there be a more pronounced acrid smell when burning
bituminous, but there will also be greater amounts of smoke, especially
immediately after loading new fuel.
• Once the volatiles have been burned o, the smoke will greatly reduce and
may even disappear.
Lignite
Lignite is only one step above peat in the geological process. Lignite coal is the
lowest grade of coal, and is sometime called brown coal. It is somewhat aky, has
high moisture, low sulfur, and the lowest carbon content of all grades of coal. In
fact, partly because of the extremely high moisture content, many lignite coals
will have a lower Btu per pound than wood. Lignite doesn’t burn very well in a
shaker-grate style outdoor furnace. Upon heating up, many types of lignite will
ake apart and those pieces will either fall through the burn grates, or stack up
on one another, preventing the ow of combustion air through the grate system.
Because of this, lignite coal is not recommended for use in the Central Boiler
Forge Outdoor Coal Furnace.
Bituminous, or soft coal, is generally
dull in color and breaks apart easily.
Because of its high moisture, low
sulfur and low carbon content,
lignite, or brown coal, is not
recommended for use in the Forge
Outdoor Coal Furnace.

14 FORGE OUTDOOR COAL FURNACE • OWNER'S MANUAL
Operating Instructions
FireStar Combustion Controller
Refer to the FireStar Operator's Manual provided with your outdoor furnace
for information about the controller.
Firebox Door Opening Procedure
This rebox door opening procedure should be followed whenever the rebox door is
opened regardless of coal type. Even if the outdoor furnace has been shut down for an
extended period, there can be a concentration of combustible gases present. Following
these instructions reduces the possibility of a ashback.
1. Make sure the outdoor furnace has power and is turned on.
2. Press the Purge button.
NOTE: Press the Purge button even if the combustion fan is running.
3. Listen to make sure the combustion fan has started and is running.
4. e purge LED and over air LED will illuminate violet. e under
air LED will illuminate violet 30 seconds into the purge cycle. After
approximately one minute, once the purge cycle is complete, these three
LEDs will turn green.
5. If there is no smoke, or only small wisps of smoke coming from the
chimney, proceed to the next step. If there are large amounts of smoke,
wait until it has subsided before continuing.
6. Standing o to the side away from the rebox door opening, gradually
open the rebox door, stopping when the rebox door handle safety recess
catches the latch roller. Wait for a minimum of 15 seconds.
NOTE: During this time you should hear the combustion fan stop.
7. If large amounts of smoke start billowing out from around the rebox
door, close the rebox door immediately and wait at least 5 minutes before
repeating steps 2 through 6.
8. If there is no smoke, or just small wisps, carefully open the rebox door all
the way while standing to the side.
Always follow these steps, including standing o to the side of the rebox door, when
opening the rebox door. Combustible gases could ashback.

15
FORGE OUTDOOR COAL FURNACE • OWNER'S MANUAL
CAUTION
Never keep the rebox door open longer than necessary. If at any time smoke or ames
start increasing to the point where they are billowing out the door, quickly shut the
rebox door and wait a few minutes before repeating the door opening procedure.
Maintaining the Ash Bed
If burning bituminous, it is very important to establish and maintain a 3-4"
ash bed on the shaker grate in order to protect the shaker grate from damage by
overheating. If burning anthracite, the ash bed will be much thinner. In either
case, the coal or wood re must not burn directly on the grate.
CAUTION
For bituminous, maintain a 3-4" deep ash bed over the shaker grate to protect from
overheating. For anthracite, the ash bed needs to be much thinner. In either case, the
coal or wood re must not burn directly on the grate. Damage to the shaker grate is not
covered by warranty.
Cold Start Firing
NOTE: These procedures apply to initial ring or refueling the outdoor furnace from a cold
start (e.g., rst ring of the season or after an extended period of down time).
Just like burning wood, burning coal can be more of an art than a science. You
may need to vary techniques to achieve best results. Over time, you will learn
the proper techniques required for a clean, consistent burn every time. is will
allow you to identify cause and eect in a variety of circumstances and what
works best for your conditions.
CAUTION
Do not burn plastic, garbage, treated wood or fuels not listed for this outdoor furnace.
CAUTION
If the water in the outdoor furnace boils, be sure to check the water level and restore
to full. Add Corrosion Inhibitor Plus™ (p/n 1650) as needed (see Water Quality and
Maintenance).
NOTE: Before ring the outdoor furnace for the rst time, make sure the proper amount
of Corrosion Inhibitor Plus™ has been added and the water level is 1" below the full mark
on the sight gauge, as the water will expand when heated.
For bituminous,
maintaining a 3-4" ash
bed on the shaker grate
protects the shaker grate
from damage caused by
overheating. However, if
the ash bed is too thick, it will reduce and
hinder performance.
For anthracite, the ash bed
that protects the shaker
grate from damage caused
by overheating will need to
be much thinner.

16 FORGE OUTDOOR COAL FURNACE • OWNER'S MANUAL
Establish Initial Ash Bed
1. Disconnect the heat load draw by turning o the pump(s).
2. Set the under and over air levels on the FireStar Combustion Controller.
See the FireStar Operating Manual for more information.
NOTE: If burning anthracite, the over air setting should be set to 0. For bituminous, it
will require over air settings that allows volatiles to burn o. These settings will require
adjustmentover time tone-tunedependingonthe type of coalusedandits composition.
3. Place crumpled-up paper around the rebox over the grates with very
small pieces of kindling on top. Light the paper and kindling.
4. Once the paper and kindling are lit, turn the controller on by pressing the
Power button.
5. Press the Ignition Assist button. e combustion blower will turn on and
keep running for an amount of time determined either by factory preset
or a setting you have specied (see FireStar Operating Manual). As the
combustion blower runs, you'll be able to tend to the re.
6. Gradually place pieces of wood on top of the burning kindling starting
with very small pieces, increasing the size of the kindling as the re grows.
Once a large, hot re is established, add a few larger pieces of wood and
then close the rebox door.
7. Allow the re to burn for at least 10-20 minutes.
8. Using the Firebox Door Opening procedure, open the rebox door.
Always follow the Firebox Door Opening procedure, including standing o to the side
of the rebox door, when opening the rebox door. Combustible gases could ashback.
9. Wait for a few seconds and then look at the re. If the re has burned to
a point where the wood is just starting to break apart, either add more
wood or coal, depending on which type of coal will be used (see following
sections for initial loading for coal types).
Anthracite - Initial Loading
1. Continue to add wood, in increasing increments (size and quantity)
until a coal bed that is at least 3" deep is established. is will require
closing and opening the rebox door (using the Firebox Door Opening
procedure) and may take up to a few hours.
2. Rake and gently agitate the wood coals to ensure that no large pieces of
wood remain in the coal bed.