Central Boiler CLASSIC User manual

CLASSIC
®
OUTDOOR WOOD FURNACE
OWNER’S MANUAL
Save This Manual
For Future Reference
Beaverton
Oregon USA
OMNI-Test Laboratories, Inc.
Tested &
Listed By
C US

2
The Classic®
by
Central Boiler, Inc.
20502 160th Street
Greenbush, MN 56726
www.centralboiler.com
The Central Boiler Classic Models CL 4436, SCL 5636,
CL 5648, and SCL 5648 are either UL or OMNI tested and
listed.
INTRODUCTION
Labeling and Terminology
The wood furnace and this manual 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 wood furnace.
WARNING: Indicates presence of a hazard which can
cause severe personal injury, death, or substantial property
damage if ignored.
CAUTION: Indicates presence of a hazard which will
or 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 wood 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.
Foreword
This manual is to be used as a guideline for installation,
operation, and maintenance of the Classic outdoor wood
furnace. This manual is organized into six sections for your
easy reference.
Section 1 relates to Operation;
Section 2 relates to Maintenance;
Section 3 relates to Installation;
Section 4 relates to Troubleshooting;
Section 5 relates to Owner Serviceable Items;
Section 6 includes General Information.
Anyoneowningoroperatingthisfurnacemustread,fully
understand, and follow all of the information in this manual.
With propermaintenance,theClassicoutdoor woodfurnace
will give many years of service; however, if replacement of
any component is desired, be sure the furnace has cooled prior
tostarting thereplacement procedure.Also,all livecoals should
be removed from the firebox before performing any
maintenance that requires the draining of water.
WARNING
Be careful when performing maintenance on the
furnace prior to it being thoroughly cooled down.
Disconnect the electrical power to the furnace and
remove all live coals from the firebox before
performing maintenance that requires the draining
ofwater orreplacementof anelectricalcomponent.
Wood Quality and Storage
It is always best to burn seasoned wood. Seasoned wood
burnsmoreefficientlyand minimizes the amount ofcreosote
formation. Wood should be stacked so that both ends are
exposed. Covering the wood to keep it out of the elements
will keep it from absorbing moisture.
CAUTION
Do not store wood within the installation
clearances listed with this manual.
INSTALLATIONS IN MASSACHUSETTS
1. All installation components must be products approved
in the Commonwealth of Massachusetts by the Gas
and Plumbing Board.
2. Maximum run of tubing from water heater to fan coil
is 50 linear feet.

3
Table of Contents
INTRODUCTION ........................................................................................................................................................ 2
Labeling and Terminology ..................................................................................................... 2
Foreword ............................................................................................................................... 2
SECTION 1 - OPERATINGINSTRUCTIONS......................................................................................................... 4
OPERATING CLEARANCES AND PRECAUTIONS ........................................................................... 4
FIRING THE FURNACE ...................................................................................................................... 4
Filling the Firebox .................................................................................................................. 4
Adjusting Water Temperature ................................................................................................ 5
CONTROL LOCATIONS ..................................................................................................................... 5
SECTION 2 - MAINTENANCE INSTRUCTIONS.................................................................................................. 6
FIREBOX MAINTENANCE .................................................................................................................. 6
MAINTENANCE SCHEDULE .............................................................................................................. 7
WATER QUALITY AND MAINTENANCE ............................................................................................ 7
POST HEATING SEASON MAINTENANCE ....................................................................................... 8
SECTION 3 - FURNACE INSTALLATION ............................................................................................................. 9
INSTALLATION CLEARANCES AND PRECAUTIONS ...................................................................... 9
PLANNING THE INSTALLATION ........................................................................................................ 9
GENERAL INSTALLATION INFORMATION ..................................................................................... 10
WATER SUPPLY LINES AND INSULATION .................................................................................... 11
General Information .............................................................................................................11
Installing .............................................................................................................................. 14
Wiring The Circulation Pumps ............................................................................................. 15
WATER HEATER INSTALLATION .................................................................................................... 15
EXISTING FORCED AIR INSTALLATION ........................................................................................ 16
HEATING MULTIPLE ZONES OR BUILDINGS ................................................................................ 19
HYDRONIC INSTALLATIONS ........................................................................................................... 20
Vented System Installation .................................................................................................. 20
Pressurized Water System Installations .............................................................................. 21
Direct Circulation Baseboard Installation ............................................................................ 23
Radiant Floor System Installations ...................................................................................... 24
High Volume Water Heating ................................................................................................ 26
Pool And/Or Hot Tub Heating .............................................................................................. 27
FINALIZING THE INSTALLATION .................................................................................................... 28
INITIAL START-UP PROCEDURES ................................................................................................. 28
SECTION 4 - TROUBLESHOOTING .................................................................................................................... 30
SECTION 5 - OWNER SERVICEABLE ITEMS ................................................................................................... 32
CIRCULATION PUMP ....................................................................................................................... 32
SOLENOID ........................................................................................................................................ 32
TEMPERATURE CONTROLLER ...................................................................................................... 32
WATER TEMPERATURE SENSOR ................................................................................................. 33
SECTION 6 - GENERALINFORMATION............................................................................................................ 34
WIRING DIAGRAMS ......................................................................................................................... 34
PARTS LISTING, CL 4436 ................................................................................................................ 35
PARTS LISTING, CL 5636 ................................................................................................................ 36
PARTS LISTING, CL 5648 & SCL 5648 ............................................................................................ 37
FURNACE MEASUREMENTS .......................................................................................................... 38
INSPECTION RECORD .................................................................................................................... 39
1 YEAR LIMITED WARRANTY ..................................................................................... BACK COVER

4
FIRING THE FURNACE
The furnace comes equipped with a digital temperature
controller which controls the water temperature at which
the furnace damper shuts down. The controller allows the
furnace to operate with a water temperature within a range
of 150-195° F.
CAUTION
CHECK WATER LEVEL! Be sure water is at the
FULL mark before firing.
CAUTION
If the furnace boils hard, be sure to check the water
level and restore to the correct level if needed.Add
Corrosion Inhibitor as needed.
The first time you fire the furnace, place dry kindling
wood near the middle of the firebox. Use a smallamount of
paper to light the fire.Add larger pieces of wood to the fire
but do not fill the firebox completely. When the water
temperature reaches the controller setting (185° F) and the
damper closes, let the furnace cycle a few times to be sure
it is operating properly; then the furnace may be filled with
more wood.After a few days of operation you will begin to
know how much wood is needed each day. If you only fill
the amount needed, it is easier to stir the ashes along the
sides of the firebox and pull them forward (see Firebox
Maintenance).
NOTE: Be sure to clean and inspect the firebox as
outlined in Section 2, Firebox Maintenance.
CAUTION
Failure to clean the firebox as indicated will result
in accelerated corrosion.
Periodically during the normal operation of the furnace,
look at the water temperature display on the furnace. It
should read the same temperature as the controller setting
(185° F). If the reading is 212° F or above, this indicates
eitheralow-water condition or a malfunctioningtemperature
controller or snap disc (unless the door and/or damper are
open or not sealing properly). If the condition persists and
the water level is correct, call your dealer for service.
Filling the Firebox
Prior to filling the firebox with wood, always pull the
hot coals forward to the draft area (front and center of the
firebox). When hot coals are pulled to the draft area before
filling wood each time, the added wood ignites faster as the
combustion air is forced through the hot coals and into the
newly added wood. If the coals are pushed to the back, a
less efficient burn will result. If needed to extend the burn
time, the furnace may be completely filled.
When filling the firebox with wood, use the following
procedure.
1. Unlatch the door; then as the door is opened, step back
from the furnace. From a distance, observe the fuel
load. Stay as far away from the furnace as possible
especially if large amounts of wood and coals are
present.
Section 1 - Operating Instructions
OPERATING CLEARANCES AND
PRECAUTIONS
Please read and observe the following information
carefullybeforeoperatingthe Classic outdoor wood furnace.
WARNING
Never fire the furnace if the water level is below
the FULL mark.
1. The Classic is to be fueled with untreated wood only.
Do not burn garbage, gasoline, rubber, engine oil,
naphtha, plastics, treated wood, or combustibles other
than wood.
2. Do not use chemicals or fluids to start the fire. Use
only paper and kindling to start an initial fire. Existing
coals left in the firebox will restart the fire after
reloading the furnace.
3. Do not store wood or other combustibles within the
installation clearances listed in Section 3. Be sure to
leave a safe amount of room to load the firebox and
clean out ashes without causing a fire hazard. Keep
the area around the furnace clear of combustible
materials. For fire safety, we recommend
maintaining a 6 foot clearance to all combustible
materials especially around door and draft areas.
Debris of wood chips and other combustibles in
the loading area may very easily be ignited if a
hot coal is spilled out of the firebox and left
unnoticed.
4. This furnace is not to be used with an automatic stoker.
5. The furnace must not be allowed to pressurize. The
vent cap is to be inspected periodically for any
obstructions or restrictions. The vent cap must fit
loosely over the vent. Do not extend or connect
anything to the vent pipe.
Fig. 1
6. All cover plates, enclosures, and guards must be secured
at all times except during maintenance, inspection,
and servicing.
7. When replacing a light bulb, use a 40 watt appliance
bulb. Do not install a bulb in excess of 60 watts.
8. In case of a power outage, either a small generator or
12V battery and a power inverter can maintain enough
electricity to operate the system.
9. If any questions should arise that cannot be answered
by the information in this manual, be sure to contact
either your dealer or heating contractor.
SECTION 1 - OPERATING INSTRUCTIONS

5
Section
1
CAUTION
Stay as far away as possible from the door area
when opening the door.
2. If necessary, clean the firebox of excess ashes and/or
crusty deposits.
3. Pull the hot coals to the draft area of the firebox.
Fig. 2
4. Load the firebox with wood being careful not to be
pinched between the wood and any part of the
furnace.
NOTE: Use extreme care if adding wood when a
large amount of wood and coals are already
present in the furnace as very hot gasses will be
coming out of the firebox door.
WARNING
When filling wood into the firebox, be careful not
to get pinched between the wood and the door
frame or any part of the furnace. Use extreme care
as large pieces of wood are difficult to handle.
5. Close and secure the door. Do not use the door to
ram wood into the furnace. Do not operate the
furnace with the door open. If the door is left open,
an uncontrolled burn will result. To return to a
controlled burn, close and secure the door.
NOTE: Creosote is an accumulation of combustion
by-products on the surfaces of wood burning
appliances.Twiceamonthduringtheheatingseason,
inspect for excessive creosote buildup on the walls,
flue, and chimney; if present, it should be removed
forproperoperationandfiresafety.Creosote if ignited
in the chimney, results in an excessively hot chimney
fire. In case of a chimney fire, close the door.
Fig. 3
Adjusting Water Temperature
The furnace high water temperature setting can be
adjusted anywhere within a temperature range from 150 -
195º F.At 10º F less than the temperature setting (10º Fbeing
the thermostatic differential), the controller will start the
draft cycle by opening the damper (and activating the
optional draft inducer if equipped). The controller has been
preset at the factory at 185º F. When OUT is indicated on
the display, the controller is calling for heat. If it is desired
to change the setting (because of a higher than normal heat
load or cooler weather) use the following procedure.
NOTE: It is not recommended to set the controller
below 165º F.
1. Press the SET button on the controller. “SP” will appear
on the display.
2. Press SET again. The set temperature will now be
displayed. The factory preset temperature is 185º F.
3. Press either the UP or DOWN button until the desired
operating temperature is reached.
4. Press SET to save the setting. “SP” will appear.
5. To exit the programming mode, either press the SET
and DOWN buttons at the same time or wait one
minute and the controller will automatically exit the
programming mode.
NOTE: The controller will only allow values
between 150 and 195º F.
CONTROL LOCATIONS
Fig. 4
Section 1 - Operating Instructions

6
FIREBOX MAINTENANCE
NOTE: Proper firebox maintenance will have direct
effect on the life of the furnace.
CAUTION
Do not burn plastic, garbage, or treated wood.
NOTE: Chloride or sulfurous gasses generated if
plastic or rubber is burned will mix with the
moisture from the wood and form sulfuric or
hydrochloric acids in the firebox creating
excessive corrosion.
It is important to stir the ashes in the firebox and pull
them forward once every three or four days to prevent the
ashes from sealing moisture on the bottom and along the
edges. It is especially important to scrape the walls and the
four corners at the ash line and below. If this maintenance
operation is not performed as directed, deterioration can
resultfrommoisturetrappedbetweentheashes and the steel.
Once each day, applyAshtrol Conditioner to the firebox.
Use a spoon as directed to broadcast powder in firebox,
alternating placement daily. One day broadcast on fire or
hotcoals,thenextdaybroadcastagainstthe walls and baffle.
Ashtrol is a pH modifier that helps to neutralize acids that
may form in the firebox.
Any heavy or solidified ashes should be removed. When
the ashes build up either to the door frame in the front or to
the top of the beveled ash pan of the firebox, they should be
removed. A hoe, ash rake, and shovel to be used for this
procedure may be purchased from your Central Boiler
dealer. Leave enough ashes and coals to relight the fire. For
your protection, wear a dust mask and protective clothing
when cleaning ashes from the firebox.
CAUTION
Always wear a dust mask and protective clothing
when cleaning ashes from the firebox.
When the ashes are cleaned out, be sure to put them in a
noncombustible container with a tight cover. It can take
many days before they are completely cooled down. Other
waste should not be placed in this container. Each time the
ashes are cleaned out, inspect the door rope to make sure it
is sealing properly.
WARNING
When cleaning the furnace, be careful not to spill
anycoals outside ofthe noncombustiblecontainer.
Once a month the bottom 12 inches of the firebox should
be scraped clean. This can be accomplished by letting the
fire get very low; then moving the coals to one side and,
using a hoe, cleaning half of the firebox. Next, move the
coalstothe other side and finish cleaning the firebox leaving
some ashes with the live coals. Finally, pull the coals and
ashestothedraftarea(frontand center of the firebox). When
the furnace is filled, the coals left in the firebox will light
the fire.
Thetopand walls of the firebox above the ash line should
be scraped clean if large, thick, or dry crusty deposits are
present on the walls or behind the baffle. A thin, tar-like
layer of creosote does not cause any problems in the
operation of the furnace. If the flue passageway behind the
baffle becomes plugged, it must be cleaned. Inspect the
chimney;cleanifan excessive buildup of creosote is present.
The ash line and below needs to be cleaned to reduce the
possibility of corrosion.
Inspect the firebox for signs of corrosion every 3 months
the first year and every 6 months thereafter. Clean firebox
walls, front and back corners; then inspect the firebox. If
excessive corrosion is visible, review your maintenance
procedures and monitor quarterly (see Maintenance
Schedule).
Periodically, lubricate door handle with a light petroleum
distillate (WD-40 or equivalent).
SECTION 2 - MAINTENANCE INSTRUCTIONS
Section 2 - Maintenance Instructions

7
MAINTENANCE SCHEDULE
Daily – BroadcastAshtrol in firebox. Alternating each day, apply once per day on
the fire then against walls and baffle. Stir, scrape, and pull ashes in firebox
forward, especially in the back corners. Check waterlevel. Be sure to close
the sight-gauge valve after checking water level.
Monthly – Check door rope; check chimney; check vent cap; remove ashes and clean
firebox.
Biannually – Complete ash removal and firebox inspection; then scrape the firebox.
This biannual inspection should be performed on new furnaces after the
first month and after the third month of operation. Use a wire brush and
small scraper to clean firebox, side wall, back wall and ash pan; then using
a light, inspect for corrosion. Lubricate solenoid plunger with a light
petroleum distillate (WD-40 or equivalent).
WATER QUALITY AND MAINTENANCE
An important part of furnace maintenance is controlling
the quality of the water in the furnace. Central Boiler
suppliesapH tape and a nitrite test kit witheachnewoutdoor
wood furnace.
Before filling the furnace with water, a sample of the
supply water that will be used to fill the furnace (softened
water is best if possible) should be tested with the pH tape.
This is a simple test in which a small sample of the water is
collected in a clean container; then dip the pH indicator
tape in the water and compare the color to the chart provided
with the test paper. If the pH test results indicate a pH level
between6.5and 8 and there arenoother known water quality
problems, then the furnace may be filled with this water. If
the water to be used to fill the furnace has a pH level of less
than 6.5 or greater than 8, a sample of this water should be
sent to a water quality test lab for recommended treatment,
thewatershouldbeconditioned,orwatershouldbesupplied
from a different source.
Central Boiler Corrosion Inhibitor (p/n 165) gives
optimum protection with an initial treatment of 2000 ppm
and a maintenance level between 1500 and 2000 ppm.
Corrosion Inhibitor should be added through the vent pipe
at the top of the furnace at the recommended rate for each
furnace. The recommended initial treatment rate for each
furnace is specified by units. One unit of the Corrosion
Inhibitor is a 3-quart container. The normal rates for the
initial treatment of the furnaces are as follows: CL 4436—
1 unit, SCL 5636 — 1 ½ units, CL 5648 and SCL 5648 — 2
units.
Immediately after adding Corrosion Inhibitor, fill the
furnace to the FULL mark on the sight gauge; then start the
pump(s). Circulate water for 24 hours and test inhibitor and
pH levels using the appropriate test kit. Use Test Kit, p/n
405 when no antifreeze is present in the water. Use Test
Kit, p/n 597, when antifreeze has been added to the water.
If the nitrite level is not at least 2000 ppm, add ½ unit of p/
n165;thencirculatewaterfor24hoursandrepeatprocedure
until the 2000 ppm level is achieved. Do not exceed 3000
ppm.After the proper nitrite level has been obtained, check
pH to make sure it registers between 8 and 9.5.
NOTE: If the system has a larger than normal water
capacity, more inhibitor should be added at a
recommended rate of one unit per 180 gallons of
water.
Beforecollecting the sample, drain about a quart of water
from the sight-gauge tube and then carefully fill the sample
container without contaminating the sample. It will be
necessarytoremovethetubefromthesight-gaugemounting
clip and bend the tube away from the furnace to collect the
sample. Be sure to properly install the sight-gauge tube and
close the valve when finished. The sight-gauge valve and
tube will drain when the valve is closed.
The water, once treated, should remain stable as long as
water is not added to the furnace. If water is added to the
system, the system water should be tested and Corrosion
Inhibitorshouldbeadded (if necessary) to maintain the same
level of protection.
NOTE: Water should not be added to the furnace
frequently as it may increase the amount of solids
in the system that can cause problems in the water
jacket. If there is a leak in the system or if the
furnace is boiling frequently causing an abnormal
water loss, the problem should be identified and
repairedimmediately. Under normaloperation,only
a small amount of water should need to be added
once each year or two.
After the initial three months of operation and every six
months thereafter, the water should be tested for the pH and
nitritelevels.These levels should be maintained as indicated
in the following chart.
Section
2
Section 2 - Maintenance Instructions

8
POST HEATING SEASON
MAINTENANCE
The water should be left in the furnace during the
non-heating season. Check pH and nitrite as described in
the Water Quality and Maintenance section; add Corrosion
Inhibitor(p/n165) as needed. If CorrosionInhibitorisadded,
run the circulation pump for two days to thoroughly mix in
thenewcorrosioninhibitor.If water is added, bring the water
up to operating temperature as soon as possible.
At the end of the season, clean all the ashes out of the
furnace. Scrape the walls and floor of the firebox taking
special care to clean at the ash line and below, especially in
the corners. Check behind the baffle and in the chimney
flue. Clean out any excessive buildup. Any large or dry
crusty deposits on the walls, baffle, or heat exchanger area
shouldberemoved.Athin, tar-like coating of creosote above
the ash line does not need to be scraped clean as it works
like a protective coating on the metal. When cleaning the
firebox, be sure to wear eye protection and a dust mask.
When the furnace is clean, carefully inspect the firebox
foranyexcessivecorrosionordeterioration.Ifanycorrosion
or deterioration is found, call your dealer. It is always better
to do furnace maintenance during the non-heating season.
After the inspection is completed, apply a thin coat of motor
oil to the firebox being sure to work oil into all corners.
Place a cover over the chimney to keep rain from entering
the furnace. Clean and oil the chimney flue to the firebox.
Once every three years, the water should be flushed from
the system and the water jacket should be rinsed (see Fig.
5). Remove the inspection panel and insulation covering
the drain to gain access to the drain. Open the drain; then
drain and flush the furnace. Close the drain securely after
flushing the furnace. Check the drain for leaks after filling
the furnace with water being certain to treat with the correct
amount of Corrosion Inhibitor. Operate the pump to
thoroughly mix the inhibitor. After confirming the seal of
the drain, insulate the area with either canned urethane foam
insulation or a mat of fiberglass insulation. Install the
inspection panel and secure with the self-tapping screws.
Fig. 5
If water is added more frequently than once during the
heating season, a complete inspection of the furnace and
plumbing should be performed.
Section 2 - Maintenance Instructions

9
Careful planning and proper installation of the outdoor
wood furnace and the entire heating system are essential
forthe ultimate in customer satisfaction and heating comfort
and efficiency. Be sure to read and observe all of the
following information in this section when installing the
furnace.
CAUTION
This wood furnace is not intended to be the only
source of heat. Should the system be left
unattended, run out of wood, or be in need of
service, a backup system should be in place to
prevent damage caused by freezing.
INSTALLATION CLEARANCES AND
PRECAUTIONS
•TheClassic isnot intended orcertified to beinstalled
inside a building.
•If this outdoor wood furnace is used to heat potable
water that has any association with commercial food
preparation or heating milk-house hot water, it is
recommended that a double wall heat exchanger be
installed. Also, a check valve (backflow preventer)
must be installed in the line used to fill water into
the system.
NOTE: All installations and operations must be in
accordance with local and state codes which may
differ from the information in this manual.
1. Installation requirements for clearances to combustibles
are as follows:
•18 inches from the back of the furnace.
•6 inches from the sides of the furnace.
•48 inches from the front of the furnace.
•18 inches from the chimney connector.
•The foundation must be noncombustible.
2. In higher populated areas, it is necessary to extend
the chimney to a height above the roofs of
surrounding buildings. All chimney extensions
should be insulated to prevent condensation from
entering the furnace firebox. When extending the
chimney, each section must be secured at each
connection joint with 4 screws to stabilize the
extension. The outer shell of each extension (that
covers the insulation) should also be fastened with 4
screws to increase stability. If extensions are added to
the standard 8 feet of chimney, a stabilizing brace or
other suitable support should be installed to ensure the
stability of the extended chimney.
NOTE: If a chimney extension or chimney
replacementisdesired,onlyusegenuineCentral
Boiler chimney components listed in the parts
section of this manual.
Fig. 6
3. A nontoxic boiler-type antifreeze may be added to
prevent freezing if the furnace is to not be fired for
extended time periods in cold weather. If antifreeze
is used, be sure to adhere to all warnings and
precautions on the label of the product being used.
NOTE: Do not use automotive or RV types of
antifreeze. Water may be kept from freezing by
running the circulating pump(s) and drawing the
heat off the building being heated by the backup
heating system.
WARNING
Vent cap must fit loosely on the vent opening. Do
not force the cap down or try to seal it tightly onto
the vent pipe. Do not extend or restrict the vent
pipe or opening. DO NOT ALLOW THE FURNACE
TO PRESSURIZE.
4. An approved chimney spark arrestor is recommended
for all installations and is required if the furnace is
used in areas with high fire risk.
5. Installation of the furnace is to be performed by a
qualified installer.
6. The qualified installer must determine how to install
this supplementary furnace to be compatible with the
existing heating source.
7. Add Central Boiler Corrosion Inhibitor (p/n 165); then
if possible, fill the furnace with softened water.
8. If any installation questions arise that cannot be
answered by the information in this manual, be sure
to contact either your dealer or Central Boiler.
SECTION 3 - FURNACE INSTALLATION
Section
3
Section 3 - Furnace Installation

10
PLANNING THE INSTALLATION
Several items must be taken into consideration when
selecting a suitable location for the Classic outdoor wood
furnace. Highlighted below are many of the key items that
mustbeconsidered when choosing a locationforthefurnace.
T Checkall pertinentstate,provincial, andlocal codes.
TCheck with your insurance company to see if they
have any location requirements.
TConsiderthe directionthatthe smokewilltravel with
the prevailing winds.
TThe shorter the distance between the furnace and
building(s) being heated, the lower the cost will be
for the installation of the supply and return water
linesand insulation.Be suretomaintain therequired
clearances to combustibles.
TThe water lines from the furnace to the building(s)
shouldnot beburied in lowlying areas withstanding
water or very high water tables.
TThe water lines should not (if at all possible) run
across an area of heavy vehicle traffic. Water lines
that run under heavy vehicle traffic areas should be
protected from excessive compression.
T If the ground where the furnace is to be placed is
eitherunstable orsubject tofrostheaving, aconcrete
foundationwith two3foot cement pilingspositioned
near the front corners should be installed.
GENERAL INSTALLATION
INFORMATION
The furnace may be installed directly on stable ground
without the necessity of pouring a slab. If the ground is
unstable you may want to either use a perimeter of patio
blocks under the base or pour a concrete foundation.
It is recommended however, that the furnace be installed
on a concrete foundation. Figure 7 identifies the foundation
dimensionsandhollowedoutareanecessaryforeach model.
A 4 to 6 inch thick concrete slab works well, but a thicker
slab may be used to obtain the desired door opening height.
If the area where the furnace is to be positioned is unstable
and/oraffectedby frostheaving,beforepouring the concrete,
dig two 8 inch holes 3 feet deep at the rear corners of the
slab to provide additional support to keep the slab from
tipping.
WARNING
Do not allow combustible materials (straw, hay, or
wood) near the base. Keep the perimeter of the
furnace clear and clean.
Fig. 7
Shut-off valves must be installed on each line so the
water lines can be shut off individually for purging air from
the lines if necessary. Be sure all fittings are metal. Do not
use plastic fittings or valves.
Using the following instructions, install and connect a
ground rod (kit p/n 6593) to the furnace. In the water supply
trench near the furnace, drive the ground rod into the ground
until the top of the ground rod is below the ground surface.
Route the ground wire from the ground rod, under the
furnace base, and over to either a vertical brace or the frame
on the furnace. Drill a 1/4 in. hole in the brace and secure
the ground terminal with a cap screw (1/4x20x3/4 in.), star
washer and nut; then secure the ground wire to the terminal.
Secure the ground wire to the ground rod with the clamp.
Tighten all hardware securely.
Fig. 8
NOTE: Prior to drilling the 1/4 in. hole in the brace,
check to see if there is already a 1/4 in. hole in the
base for the ground. Some models have a hole
predrilled in the base for the ground terminal.
Section 3 - Furnace Installation

11
Access to the hot and cold outlets is gained by opening
the control panel on the right-hand side of the furnace. The
upper outlets are the hot (supply) outlets and the lower
outlets are the cold (return) outlets. This allows for the
mountingofthecirculationpumpsonthefurnace.Ifdesired,
the circulation pumps may also be installed in the building
being heated. Figures 9 & 10 illustrate proper water line
and pump installations. Fig. 9
Fig. 10
WATER SUPPLY LINESAND INSULATION
General Information
The water lines to be used are 1-inch (1 ¼ -inch on large
heat loads) CentralPEX crosslink polyethylene lines (rated
for 100 PSI at 180° F). CentralTherm foam pipe insulation
(p/n 241 or 242) should be used to insulate the lines (see
Fig. 11) and they should be covered with Central Therm
Sleeve. Installation of the water lines and insulation into a
continuous length of Central Therm Sleeve will greatly
reduce heat loss caused by ground water contact.Also, use
of Central Therm Sleeve for temporary above ground
applications (4-6 months) will reduce the effects of
ultraviolet rays on the water lines and insulation.
Central Boiler now offers a convenient alternative to
orderingandassemblingCentral PEX tubing, CentralTherm
insulation, and Central Therm Sleeve. CentralFlex™ is a
preassembled set of two 1 in. PEX tubes surounded by
insulation and encased in a waterproof corrugated jacket. It
is available in 100 and 500 foot lengths.
The water lines should be buried in a trench
approximately 12 inches deep. The water lines should not
beburiedin low lying areaswithstandingwater.Historically,
lines buried deep (3 to 4 feet) have been known to have a
greater number of problems especially when ground water
contacts the water lines causing an excessive heat loss and
greatly increasing the amount of wood consumption. An
exception to the previously stated depth of the lines is
necessary if the lines run across an area of heavy vehicle
traffic. In above ground applications where the lines will
not be buried in a trench, the lines and insulation should be
covered as exposure to ultraviolet rays will cause
deterioration of the water lines and insulation.
Section 3 - Furnace Installation
Section
3

12
Fig. 11 Do not use a drain tile pipe, bubble wrap, or PVC pipe
forwaterlinesunless these pipes can be installed in amanner
that allows the drainage of any water that could possibly
enter. If the water supply and return lines are not insulated
properly, there can be excessive heat loss. This heat loss
can greatly increase the wood consumption.
For a single building water to air heat exchanger system,
the direction of water flow is to be as follows: from hot
outlet on the outdoor furnace to the bottom of the domestic
water heater exchanger, to the lower fitting of the heat
exchanger on the existing furnace, and returned to the cold
return of the outdoor furnace.
NOTE: The direction of water flow is very important
for the proper operation of the furnace.
The circulation pump(s) must be installed in the hot
supply line(s) with the arrow on each pump pointed away
from the furnace. In order to avoid circulation problems, do
not install the pump(s) in the return line(s).
Fig. 12
Section 3 - Furnace Installation

13
If not mounted on the furnace, the circulation pump(s)
need to be mounted 4 to 5 feet lower than the top water
level in the furnace (see Fig. 13 & 14). It is recommended
tomountthepump(s)atthe furnace especially if the building
being heated is higher than the furnace or if there is a large
rise in the water lines between the furnace and the building
(see Fig. 15 & 16). Hot water boils at a lower temperature
when pulled uphill (because it is at a lower pressure);
therefore, hot water must be pusheduphill to ensure proper
circulation. Shut-off valves should be installed on both sides
of each pump so if it becomes necessary to repair or replace
the pump, the water can be shut off on both sides of the
pump. A screen or filter with a sediment chamber may be
installed in the line to remove foreign particles which might
be present in the water. The following guidelines must be
adhered to when installing the circulation pump(s).
A. The pump motor must be installed in a horizontal
position.
B. The junction box must be located above the pump
motor.
C. Do not run the circulation pump until the system has
been tested for leaks and filled with water.
NOTE: Be sure to follow the pump installation
instructions that are supplied with the pump if they
differ from the information contained in this
manual.
Fig. 13
When the pump is located inside the building to be
heated, a minimum of 4 feet between the water level in the
outdoor furnace and the highest point of the water line
between the furnace and the building must be maintained.
NOTE: The circulation pump(s) must be installed
in the hot supply line(s).
Fig. 14
Fig. 15
Fig. 16
Manual air bleeders may be installed in the high points
of the water lines where air may get trapped and cause
circulation problems. Water can be pumped to levels higher
than the furnace as long as the pump is pushing the water to
the higher level and providing there are no air leaks in the
system (see Fig. 17).
Fig. 17
Section 3 - Furnace Installation
Section
3

14
Installing
NOTE: If installing CentralFlex™, the tubing,
insulation,and sleeveassemblyinstructions inthis
section may be ignored.
Prior to installing the water lines in the insulation,
mark both ends of the hot line so that the hot water line
can be identified for correct installation. The hot fitting
on the furnace takes the water from near the top of the water
jacket and the return is lower on the water jacket. It is very
important to keep the water lines properly identified.
When installing the water lines, an installation allowance
for expansion and contraction of the lines must be made. If
the water lines are mounted solid to the furnace or inside
the building, the lines may kink or the fittings may be pulled
apart causing an immediate water loss from the furnace.
Central PEX water lines can have an expansion/contraction
rate up to 0.95 in./100ft/10°F.
A 14-2 underground rated wire (2 wires plus ground)
may be buried in the same trench to supply the furnace with
electricity.A larger wire diameter may be needed if the run
is over 200 feet. When installing the electrical supply for
the furnace, it is recommended that the incoming fuse or
circuit breaker not exceed 15 amps. The 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/NFPA70 and/or the Canadian Electrical Code
Part 1, CSA C22.1 Electrical Code.
NOTE: If unavoidable that the trench is to be run
through an area of ponding water, the installer
must make certain that water will not enter the
installation enclosure. One option is to encase the
water lines, insulation, and sleeve in corrugated
flexible tubing and digging the trench with a slight
slope to one direction or the other (preferably away
from the building) to allow drainage of any water
that may enter the tube.
1. Remove the siding panel and base trim below the
control panel. Dig a trench 12 inches deep between
the furnace and building(s) to be heated; then make
an entrance for the lines into the building(s).
WARNING
Beforetrenching, besure to callfor locatorservice.
2. Mark both ends of the hot water line; then install both
water lines in the Central Therm foam pipe insulation
using the following procedure:
A. Using a large mitre box and a fine tooth saw, trim
both ends of each insulation section.
NOTE: The insulation sections must be trimmed
square so they can be glued together during the
installation process.
B. To make inserting the water lines easier in the
insulation, insert a rod into the end of each water
line; then securely tape the rods to the water lines.
NOTE: The rods should be long enough to be
inserted into the insulation section and grabbed
from the other end.
C. For each insulation section, slide the rods into the
insulation section; then pull the water line through
the insulation. Continue until the water lines have
been threaded into all insulation sections.
Fig. 18
D. Using contact cement, glue the ends of the
insulation sections together; then using tile tape,
tape the perimeter of each seam.
E. Measure the length of Central Therm Sleeve
necessarytorunthe entire lengthofthe installation,
add two additional feet (minimum), and cut. Slide
the sleeve over the insulation; then wrap each end
and secure with duct tape. Waterproof each end
with silicone or other waterproofing agent.
3. Lay the supply lines into the trench and feed one end
into the building. Apply sealant around the lines
where they enter the building. Do not backfill the
trench until the water lines have been tested to ensure
there are no leaks.
NOTE: All holes made in basement or building
walls are to be completely sealed to prevent water
from entering the building.
4. Connect the water lines to the furnace and building
allowing for expansion and contraction of the lines
at each end.
5. Install the base trim; then using sand or fine dirt, back
fill the perimeter of the water line enclosure to the
top, inner edge of the base. Install the siding panel.
Fig. 18a
Section 3 - Furnace Installation

15
Wiring The Circulation Pumps
Upon completion of the water lines and circulation
pump(s) installation, the circulation pump(s) must be
properly wired using the following procedure. Perform the
procedure on each pump and power cord assembly. Power
cords must be UL listed and rated for 221° F.
WARNING
Do not attempt service inside the electrical control
panel without first disconnecting the electrical
power at the main power source.
NOTE: Any electrical installation should be done
by a certified electrician in accordance with all
applicable codes.
1. Remove the screw securing the capacitor box cover;
then remove the cover.
2. Slide the metal strain relief onto the end of the cord
assembly; then insert the end of the cord assembly
into the capacitor box. Secure the strain relief to the
box and cord assembly. Tighten securely.
3. Slide the green wire beneath the green screw; tighten
securely. Join the white wires and secure with a wire
nut. Join the yellow and black wires and secure with
a wire nut.
4. Carefully position all wires within the capacitor box
and install the cover. Secure with the screw.
5. Plug the cord into the receptacle. Route or tie the cord
so it does not contact any hot areas of the furnace or
water lines.
6. Insulate the areas around the water lines and pump(s);
then install and secure the cover.
Fig. 19
NOTE: If installing three pumps, use a UL approved
splitter on the receptacle outlet.
CAUTION
Maximumloadoftheoutletis10A,120VAC,and60Hz.
WATER HEATER INSTALLATION
Installing a domestic hot water heat exchanger in the
buildingthatis being heated is an inexpensive waytocapture
additionalsavingsfrominstallingtheoutdoorwoodfurnace.
The hot water line from the furnace should be plumbed first
to the water heater heat exchanger and then to the balance
of the heating system.
When necessary in certain applications, a 3-way zone
valve should be installed so that during the non-heating
season, the water heater may be operated without operating
the entire heating system. A tempering valve (or anti-scald
valve) is to be installed in the hot water outlet from the
water heater. Install a tee in a fitting on the top of the water
heater (see Fig. 20) for the hot water heat exchanger.
NOTE: If the water heater has been in service and
contains an anode rod, flush the water heater prior
to installing the hot water heat exchanger as
existing anode rod residue may tend to plug the
heat exchanger.
Fig. 20
WARNING
DO NOT disable or remove any safety reliefs or
controls. Turn off the power to the water heater
before starting the installation process.
Section 3 - Furnace Installation
Section
3

16
EXISTING FORCED AIR
INSTALLATION
When the Classic furnace is installed in conjunction with
an existing forced air system, a water-to-air heat exchanger
is to be mounted in the plenum or duct work of the existing
furnace. Heated water from the outdoor wood furnace
continuously flows through the water to air heat exchanger.
When the thermostat senses the need for heat, the fan on
the existing heating system forces air through this heat
exchanger transferring heat throughout the existing
ductwork.
If an air conditioning coil is located in the plenum, the
heat exchanger should be mounted between the fan and the
air conditioning coil so the heat exchanger will not freeze
up when the air conditioner is being used. The heat
exchanger should not be installed in the cold-air return of
the existing forced air furnace because the possibility exists
that components of the existing furnace could overheat and
cause the existing furnace to operate other than intended.
The heat exchanger may be mounted either horizontally or
vertically with the outlets on the side (see Fig. 21). In all
applications,theheatexchangermust be mounted level from
front to back, with the outlets on the side. If the outlets are
positioned upward or if the exchanger is not level, an air
lock can restrict the water circulation and reduce the amount
of heat transfer. The lower fitting is the inlet from the
outdoor wood furnace and the top fitting is the outlet for
return to the outdoor wood furnace. If the plenum is larger
than the heat exchanger, it should be mounted in the center
without gaps on the sides that would allow air to flow
around the heat exchanger.All air must be directed through
the face of the exchanger. Be sure to consider the airflow
through the ductwork so heat isn’t blocked off to parts of
the building.
Fig. 21
Adding a heat exchanger coil in the hot air plenum or
ductwork of the existing furnace may decrease the air flow in
thesystem. Theexistingheating (gasorelectric) systemshould
be operated before adding the heat exchanger. The air
temperature rise should be measured with the system running
for an adequate amount of time to get a stabilized temperature
reading.Theheat exchangercanthen beinstalledin thesystem.
The existing heating system should be operated again and the
air flow should be adjusted to maintain the same temperature
reading. The air flow may have to be increased to accomplish
this. On a belt-drive system, the blower pulley and/or motor
pulley may be changed but the electrical current flowing
throughthe motorshall notbechanged toexceed thenameplate
rating. A blower motor of larger power may be used. In most
cases on a direct-drive system, the blower motor will not need
to be replaced; however, the speed of the blower motor may
have to be increased.
CAUTION
When installing the heat exchanger, be sure none
of the existing system safety controls are disabled.
NOTE: Any electrical installation should be done
by a certified electrician in accordance with all
applicable codes.
A snap disc temperature control should be installed on
the heat exchanger manifold to provide an interlock for the
air conditioner. This prevents the air conditioner from
operating when the water temperature is higher than 140° F.
There are several methods to install thermostatic controls
for this type of installation. If the existing heating system is
controlled by a 4 wire, 24 volt thermostat, the simplest
method is to add a second 24 volt thermostat. The secondary
thermostat will control the room temperature at which the
fan on the existing heating system will activate with heat
being drawn from the Classic furnace and should be set to
the desired room temperature. The existing heating system
thermostat should be set to a temperature 4-5° lower than
the secondary thermostat and controls the temperature at
which the existing heating system will activate as a backup
to the outdoor wood furnace. Connect the thermostats
according to the following wiring diagram (see Fig. 22).
Fig. 22
Section 3 - Furnace Installation

17
An alternative method is to install a line voltage
thermostat to control the blower on the existing furnace. In
this installation, a 120-volt line is run from the thermostat
to the furnace where one wire is connected to the hot (line
feed) and the other wire to the furnace blower wire. A low
water temperature switch may be installed to shut off the
blowerif the temperature of the water is too low.This switch
isconnectedinseriestothewirecomingfromthethermostat
previously mentioned. This switch must be installed so that
it does not affect the existing system thermostat.
NOTE: If a low water temperature switch is not
installed, the fan will run continuously even when
the outdoor wood furnace is out of wood. Not
installing the switch is acceptable if it is desired
to keep the water in the furnace the same
temperature as the air temperature in the house
to prevent the water in the furnace from freezing.
Fig. 23
Section 3 - Furnace Installation
Section
3

18
Fig. 24
Section 3 - Furnace Installation

19
HEATING MULTIPLE ZONES OR BUILDINGS
A single pump and manifold may be used to heat more than one zone or building as long as the return water can be
maintained above 150°F. If the return water temperature can not be maintained above this level, then a separate pump
should be used for each building and a one way swing check valve should be installed on the outlet side of each pump.
Side panel models offer three sets of outlets (for up to three zones or buildings without the need for manifolds) for the
mounting of up to three pumps on the furnace.
Fig. 25
Central Boiler 2004
Section 3 - Furnace Installation
Section
3

20
HYDRONIC INSTALLATIONS
If a water-to-water heat exchanger is to be used with an
existing heating system, the existing heating system must
be able to adequately heat the building with a water
temperatureofapproximately165°F.Some existing fin tube
baseboard hot water heating systems are designed to operate
withwatertemperatures up to 220°For higher.If the existing
hot water heating system has had trouble maintaining the
temperatures in the home at any time during cold weather
before installing the outdoor wood furnace, then the system
is not adequate to work properly. Evaluate the existing hot
water system before starting the installation. If the existing
heatingsystemismarginalor designed to operate with water
temperatures above 165° F, there are alternative installation
procedures that will make the system work very well with
the Classic outdoor wood furnace. These include:
1. More fin tube water baseboard heaters can be added.
2. A water to air heat exchanger with a thermostatic
controlled fan can be installed in the lower part of
the building being heated. This can increase the
amount of heat added to the building to maintain a
constant temperature. This heat exchanger can be
added in the return line of the outdoor system after
the water-to-water heat exchanger.
3. An additional radiant heating circuit can be added to
heat areas that require additional heat.
Vented System Installation
NOTE: Any changes in the existing boiler should
be done by a certified plumber in accordance with
applicable codes.
Wheninstalling the outdoor wood furnace in conjunction
with an existing hot water system, it can be connected
directly into the existing system changing it to an
atmospheric vented system. The hot supply line from the
furnace can be connected into the top of the existing boiler
and returned to the outdoor wood furnace from the bottom
of the boiler (see Fig. 26). Use one pump to continuously
circulate the water from the outdoor wood furnace through
the existing boiler and back to the outdoor wood furnace.
CAUTION
The outdoor wood furnace must NEVER be
pressurized. The vent cap must always be loose.
Do not extend the vent pipe. The furnace will be
damaged if it is pressurized.
When the existing system is connected to the outdoor
system as illustrated in Fig. 26, the circulating pump(s) in
the existing system must be located in the hot supply line(s),
not in the return line(s).
Fig. 26
Section 3 - Furnace Installation