Wood master Flex Fuel User manual

Northwest Manufacturing, Inc
600 Polk Ave SW
Red Lake Falls, MN 56750
www.woodmaster.com
Retain this manual
Owners Manual
Manual PN: 7994-300

2Flex Fuel Owner’s Manual March 2011
Congratulations on your decision to purchase the
WoodMaster Flex fuel. You will be extremely pleased with this product, which stands out from the
competition in terms of ease of use, furnace eciency and low emissions.
May quality, workmanship and on going product enhancement never be just a passing thought, but rath-
er an everyday tangible aspect, that improves the lives of our employees, dealers, and customers alike.
Burning Wood
Burning Pellets

3
March 2011 Flex Fuel Owner’s Manual
1. Contents ....................................................................................................................... 3
2. Terms............................................................................................................................. 5
3. Safety ........................................................................................................................... 7
4. Features ....................................................................................................................... 9
5. Installation ................................................................................................................ 1 0
5.1 Location .......................................................................................................................................... 10
5.2 Display ............................................................................................................................................. 11
5.3 Chimney ......................................................................................................................................... 11
5.4 Water Connections ...................................................................................................................... 11
5.5 Electrical Connections ............................................................................................................... 17
5.6 I/O Board ........................................................................................................................................ 18
5.7 Connecting to Heating System .............................................................................................. 20
6. Fuels............................................................................................................................ 21
6.1 Pellets .............................................................................................................................................. 21
6.2 Bulk Materials ............................................................................................................................... 21
7. Switching the Furnace On/O .................................................................................. 2 2
7.1 Switching the Furnace On......................................................................................................... 22
7.2 Switching the Furnace O ........................................................................................................ 23
8. Display ....................................................................................................................... 24
8.1 The Start Screen ........................................................................................................................... 25
8.2 Menu Navigation ......................................................................................................................... 26
9. Basic Furnace Settings .............................................................................................. 2 8
9.1 Set Required Furnace Values ................................................................................................... 28
9.2 Select Furnace Operating Mode ............................................................................................ 28
9.3 Boiler Cleaning.............................................................................................................................. 28
9.4 Vacuum Output/Heat Exchanger ........................................................................................... 28
9.5 Setting the Clock/Date .............................................................................................................. 29
9.6 Service Menu ................................................................................................................................ 29
9.7 Alarm Protocol .............................................................................................................................. 29
9.8 Output Test - Heating Cycle ..................................................................................................... 30
9.9 Output Test - Boiler ..................................................................................................................... 30
9.10 Language Selection/Temperature Scale Selection ....................................................... 31
9.11 Hour Meter .................................................................................................................................. 32
10. Operating Modes .................................................................................................... 33
10.1 View of the Selected Operating Mode .............................................................................. 33
10.2 Setting the Furnace Operating Mode ............................................................................... 33
10.3 Changing the Furnace Operating Mode .......................................................................... 34
1: Table of Contents

4Flex Fuel Owner’s Manual March 2011
1: Table of Contents
11. Bulk Materials Mode ............................................................................................... 37
11.1 General Information ................................................................................................................ 37
11.2 Pre-Firing Checks ....................................................................................................................... 37
11.3 Firing .............................................................................................................................................. 38
11.4 Smoldering Gas Extraction and Adding Fuel .................................................................. 41
11.5 Combustion Completed ......................................................................................................... 41
11.6 Status Lines During Furnace Operating Mode “Bulk Materials” ............................... 43
11.7 Indications.................................................................................................................................... 43
12. Bulk Materials Auto Mode ...................................................................................... 45
12.1 General Information ................................................................................................................ 45
12.2 Pre-Firing Checks ...................................................................................................................... 45
12.3 Filling the Furnace ..................................................................................................................... 46
12.4 Setting the Release Period .................................................................................................... 48
12.5 Activating “Bulk materials auto control”............................................................................ 51
12.6 Status Lines for Operating mode “Bulk materials auto control”................................ 51
12.7 Automatic Change-Over of Furnace Operating Mode................................................. 51
13. Pellets Auto Control ................................................................................................ 5 2
13.1 General Information ................................................................................................................ 52
13.2 Pre-Firing Checks ...................................................................................................................... 52
13.3 Adjusting the Pellet Slide ....................................................................................................... 53
13.4 Starting the Furnace in Operating Mode “Pellets Auto Control”............................... 55
13.5 Opening the Firebox Door During “Pellets Auto Control”........................................... 55
13.6 Status Lines for Operating Mode “Pellets Auto Control”.............................................. 56
14. Buer/Thermal Storage .......................................................................................... 6 1
14.1 Buer Settings .......................................................................................................................... 61
15. Maintenance ........................................................................................................... 6 3
15.1 General Information ................................................................................................................ 63
15.2 Cleaning the Furnace .............................................................................................................. 63
16. Error Messages ........................................................................................................ 66
17. Troubleshooting ..................................................................................................... 69
18. Specications .......................................................................................................... 7 0
19. Warranty .................................................................................................................. 7 1

5
March 2011 Flex Fuel Owner’s Manual
2: Terms
Flex fuel - Hydronic heater designed to burn multiple wood fuel types
Furnace/Boiler AKA appliance, stove - An apparatus in which heat may be generated, as for heating
homes, buildings, pools and radiant heat via water
Seasoned Wood - Wood that has dried to an internal moisture content of 25% or less
Cord Wood - Lengths of wood that are typically 8’long
Chunk Wood - Pieces cut from cord wood that have not been split or seasoned
Bulk Materials - Split, seasoned wood cut less that 26”long
Kindling - Small, easily combustible material for starting a re
Green Wood - Wood that is recently cut and has a high moisture content
Pellets - Wood sawdust compressed into small cylinders to be used as fuel
Flue - AKA Chimney - Any duct or passage for air, gas, or exhaust
Air Factor - Indicator of oxygen level of the ue gas
Display - AKA Eco manager - screen for user to change settings and parameters
I/O Board - Input/output board that controls the furnace functions
Firebox - Chamber where fuel is loaded or conveyed
Water Jacket - Steel casing that surrounds the rebox and holds the water/antifreeze
Funnel - Casting located on the bottom of the rebox
Insert - Replaceable part designed for particular fuels located in the funnel grate
Refractory - Bricks of various shapes lining the ash chamber causing gasication
Turbulator - Cleaning mechanism located in heat exchangers that also increase eciency
Draft Inducer - Fan that manages the combustion process
Igniter - Hot air blower for igniting fuel
Gasication - Extracting gas from the wood to be burnt to heat water
Buer - AKA Thermal Storage - Tanks used to store hot water

6Flex Fuel Owner’s Manual March 2011
2: Terms
Air Ratio - See air factor
ESC - Function on display controlled by the operator to move back
Fire Irons - Metal pokers and scrapers used for ash/wood cleaning & maintenance
Fault - An error that causes an alarm
Hopper - Storage container used to hold pellets
Fuel Shut O - Metal gate used to isolate fuel storage from high temperatures and/or re
Call for Heat - Heat demands from circuits utilized in heating system designs
Release - A demand set by the operator for the furnace to carry out a function
Blow Down - The process of removing sediment deposits from the furnace/buer tank(s) by draining water
from the bottom of the unit(s) until the water runs clean
Lambda - AKA Oxygen Sensor - A sensor that measures the amount of oxygen in the ue gas

7
March 2011 Flex Fuel Owner’s Manual
3: Safety
• AllinstallationandoperationsmustfollowSTATEandLOCALCODESforwiring,plumbing,andringofthis
unit. These CODES may dier from this manual. Installation must be performed by a qualied installer.
• AllFlexfuelmodelsoperateatatmosphericpressure.DONOTobstruct,block,orplugtheoverowtank.
• Neveropentheashdoorduringoperation!
• Anyonewhoisnotfamiliarwithand/orhasnotbeentrainedtooperatetheFlexfuelmaynot
operate the system. Only responsible adults should operate your furnace. If the furnace is not red
properly damage could result and the warranty may be voided.
• Neverallowchildrentoplaynearortamperwiththefurnace,fuels,tanksoranyotherpartofthesystem.
• Alwayskeeptheareaaround,andinfrontoffueldoorcleanandfreefromcombustiblematerials.
• Keepanimalsawayfromthefurnace.
• Theoperationmaynotbecontinuedorrestartedintheeventofvisibledamages(forexample,waterleaks,
thermal distortion, traces of smoke or re, mechanical damages, etc.). Any damages must be repaired. In
the event of any doubts, please contact your authorized WoodMaster Flex fuel Dealer.
• Freezeprotectionmustbeguaranteedinallwater-bearingpartsintheeventofextensiveidle
periods of the system. Note: Your Flex fuel is not intended to be your only heat source. In the event that
your existing heat source will not back up your Flex fuel antifreeze must be used.
• TheFlexfuelsystemmustnotbeexposedtoexternalmechanicalstress(forexample,asstorage,climbing
support, brace, or similar). This also applies for single parts (doors, covers, etc.).
• Onlytouchthehandlesduringtheoperation.Temperaturesatotherpoints(forexample,chimney,ash
door, buer tank, lines…) can be very high.
• RemembertorecyclethepackagingyourFlexfuelwasshippedin.Inthelongtermproperlyrecyclethe
furnace if you replace your Flex fuel.
• TheFlexfuelmustbeoperatedexclusivelyaccordingtotheguidelinesforplanning,assembly,
regulations, statutes and product related instructions. The manufacturer is not liable for damages and
their results, if they occurred due to improper assembly, operation, application and also inadequate
maintenance and cleaning.
• Donotconnectthisunittoachimneyueservinganotherappliance.Followallstate/localcodes.
• Loadwoodcarefullytoavoidinjurytohandsandngersthatmaycomeintocontactwithfurnace
opening.
• Readandfollowthesedirectionscarefully.RetainthismanualforaslongasyouownyourFlexfuel.

8Flex Fuel Owner’s Manual March 2011
3: Safety
UL Certication

9
March 2011 Flex Fuel Owner’s Manual
4: Features
1. Ash Door - A large opening to make cleaning the ash chamber simple and easy.
2. Firebox door - A large opening to make lling and cleaning the rebox simple and easy
3. Display for Controller - Designed for easy operation.
4. I/O Board - An input output board that controls the furnace as well as where optional accessories plug in.
5. Ash Chamber - A large compartment to reduce the amount of times the ash needs to be removed.
6. Firebox - Large volume to hold enough wood for up to a four hour burn at max burn rate.
7. Inserts for Pellets or Bulk Materials - Easily changed when switching operating mode. No tools required.
8. Heat Exchanger - Ecient transfer of heat and are self cleaning.
9. Flange for Automatic Loading (Both Sides) - Allows the optional pellet arm to be installed on either side.
10. Exhaust Pipe - Allows easy installation to both new and existing chimneys.
11. Smoldering Gas Duct - Prevents any exhaust from exiting the furnace when the rebox door is open.
12. STL (Safety Temp Limiter) - Safety switch that shuts down the furnace in the even of it overheating.
All photos in this manual represent the Flex fuel 30 kW unless otherwise noted

10 Flex Fuel Owner’s Manual March 2011
5: Installation
Your Flex fuel must be installed by a professional and should follow all local, state and federal laws
and regulations. Any use of an unapproved installation may result in a voided warranty.
It is recommended to have your installation approved by WoodMaster.
5.1 Location
Your Flex fuel can only be installed indoors where the temperature will not fall below 50°F. The furnace
may be installed inside the building that it serves or in an out building. Your Flex fuel must not be
allowed to freeze. Your Flex fuel does not need to be installed in the same structure that it serves.
Ensure that the oor that the furnace is placed on is level and able to support the weight of the furnace
plus the additional weight of the water and fuel.
There should be ample room around your Flex fuel to make loading and cleaning your furnace easier.
This area should also be clear of any easily combustible materials. Minimum clearances requirements is
11 inches for the top, 14 inches for the sides, 19.5 inches for the back and open to the front.
The room where the furnace is placed should allow ample venting to ensure proper air ow to the
furnace. The vent size requirements are 31 square inches for the Flex fuel 30 kW and 62 square inches for
the Flex fuel 60 kW.
Ensure the feet are in the bottom of the furnace. adjust the feet so the furnace sits level and the feet are
loaded evenly.
Below are the dimensions for both the Flex fuel 30 kW and Flex fuel 60 kW including all optional
accessories and chimney.
Chimney Mount
Pellet Tank
Pellet Auger
Igniter
15.00
17.00
R14.00
R4.00
57.00
40.00
38.00
28.25
11.25
4.25
24.00
58.25
6.25
Chimney Mount
Pellet Tank
Pellet Auger
Igniter
15.50
19.00
R14.00
R5.00
53.00 51.00
30.00
72.00
13.00
4.25
32.50
71.00
66.75
6.25
62.50
30 kW 60 kW

11
March 2011 Flex Fuel Owner’s Manual
5: Installation
5.4 Water Connections
The following layouts are basic conguration for the furnace water connections. Contact your
WoodMaster Flex fuel Dealer for additional layouts. Insulate the lines if desired to prevent heat loss.
1” line is recommended for the Flex fuel 30 kW and 1.25” line is recommended for the Flex fuel 60 kW.
Furnace and Buer in
the same building.
5.2 Display
Remove the hood of the furnace by lifting it to access the displays mounting position.
Plug the display into the intended connector on the I/O board.
Screw the display to the furnace using the supplied hardware.
5.3 Chimney
The ue pipe is to be installed is a rising chimney, and must be 6 inches for the 30 kW and 8 inches for
the 60 kW.
Elbows should not be used, T’s are recommended to allow for the cleaning of the ue pipe.
For every one foot of horizontal pipe three feet of vertical pipe is required.
A barometric damper must be used to allow proper ow. The damper must be installed as close to the
furnace as possible.
The chimney draw must be 0.1 mbars.
Chimneys must follow all state and local codes.
Your Flex fuel can be vented into an existing chimney as long as the chimney ts the necessary criteria.
Furnace
Supply
Pump
Diverting Valve
Diverting
Valve
Temp
Probe
Return to
Furnace
Return from
Storage Tank
Supply to
Storage Tank
Side View
Diverting Valve
Expansion Tank Expansion Tank
Temp
Probe
Temp
Probe
This document contains information that is property of
Northwest Mfg. No reproductions or duplications of this
document in whole or part shall be made without written
authorization from Northwest Mfg.
This is a SUGGESTED layout only. user must determine if
system layout will work for their particular application.
User should check and follow all state and local codes.
Heat Zone SupplyHeat Zone Return
Clear
1” Pex
Sight
Gauge
Vent Cap
Furnace Supply
Pump
Temp Head
1” Copper Line
Diverting
Valve
Temp
Probe
Furnace
Drain
Return to
Furnace
Return from
Storage Tank
Supply to
Storage Tank
Back View
Storage
Tank

12 Flex Fuel Owner’s Manual March 2011
5: Installation
Furnace and Buer in
separate buildings
running with a plate
pump.
Furnace and Buer in
separate buildings
running without a
plate pump.
Pump
Plate
Pump
Diverting Valve
10 Gal
Expansion
Tank
20 Gal
Expansion
Tank
Temp
Probe
Temp
Probe
Furnace
Plate
This document contains information that is property of
Northwest Mfg. No reproductions or duplications of this
Document in whole or part shall be made without written
Authorization from Northwest Mfg.
This is a SUGGESTED layout only. User must determine if
system layout will work for their particular application.
User should check and follow all state and local codes.
Heat Zone Supply
Heat Zone Return
Vent Cap
Vent Cap
Furnace Supply
Pump
Temp Head
1” Copper Line
Diverting
Valve Temp
Probe
Furnace
Drain
Return to
Furnace
Return
from
Storage
Tank
Supply to
Storage Tank
Storage
Tank
The Furnace must be antifreezed to prevent
the outside lines from freezing. Temperature
probe wires should run from the furnace to
the tank so that the tank temperatures can
be read at the furnace. Doing so aides in
determining load size.
Plate zone pump must run continuously or
wired to run simultaneously with the
furnace pump to take heat o the furnace
plate when furnace is heating.
Pump
Diverting Valve
10 Gal
Expansion
Tank
20 Gal
Expansion
Tank
Temp
Probe
Temp
Probe
Furnace
Plate
This document contains information that is property of
Northwest Mfg. No reproductions or duplications of this
Document in whole or part shall be made without written
Authorization from Northwest Mfg.
This is a SUGGESTED layout only. User must determine if
system layout will work for their particular application.
User should check and follow all state and local codes.
Heat Zone Supply
Heat Zone Return
Vent Cap
Vent Cap
Furnace Supply
Pump
Temp Head
1” Copper Line
Diverting
Valve Temp
Probe
Furnace
Drain
Return to
Furnace
Return
from
Storage
Tank
Supply to
Storage Tank
Storage
Tank
The Furnace must be antifreezed to prevent
the outside lines from freezing. Temperature
probe wires should run from the furnace to
the tank so that the tank temperatures can
be read at the furnace. Doing so aides in
determining load size.
Heat zone pump must run continuously to
take heat o the furnace plate when
furnace is heating.

13
March 2011 Flex Fuel Owner’s Manual
5: Installation
Plumbing the Rear of the Furnace
The images below show how to connect the pump to the back of your Flex fuel furnace using the
installation kit. Please note that the circulation pump and copper lines are not included in the kit.
All plumbing should be done by a qualied plumber. This kit is a 1”kit, a 1.25”kit (020-0010) is available.
To Expansion Tank
Furnace Supply
Pump
Diverting Valve
Diverting
Valve
Temp
Probe
Return to
Furnace
Return from
Storage Tank
Supply to
Storage Tank
Side View
To Expansion Tank
Furnace Supply
Pump
Temp Head
1” Copper Line
Diverting
Valve
Temp
Probe
Furnace
Drain
Return to
Furnace
Return from
Storage Tank
Supply to
Storage Tank
Back View
1” Furnace Plumbing Kit (020-0006)
Part No. Description
0030-195 3/4” F Hose x 1/2”
0020-198 1/2” Ball Valve
0020-224 1” Sw St 90 (3)
0020-227 1” MPT x 1” F Sw (2)
0020-230 1” Sw T
0020-233 1” M Sw x 1” FPT (2)
0020-250 1”x 2” Nipple
0020-258 1 1/2 “ x 1” Reducer (3)
0020-270 1 1/2” Street 90
0020-271 1 1/2”Tee (2)
0020-272 1 1/2” x 1/2” Reducer
0020-366 ISO Pump Flanges
0109-003 1/2”Thermowell
63025 Diverting Valve
57094 Thermostatic Head
Copper Pipe
Copper Pipe
Copper Pipe
0020-258
1 1/2 “ x 1” Reducer
0020-258
1 1/2 “ x 1” Reducer
0020-258
1 1/2 “ x 1” Reducer
0020-250
1”x 2” Nipple
0020-366
ISO Pump Flanges
0020-227
1” MPT x 1” F Sw
0020-227
1” MPT x 1” F Sw
63025
Diverting Valve
57094
Thermostatic Head
0020-224
1” Sw St 90
0020-224
1” Sw St 90
0020-224
1” Sw St 90
0020-233
1” M Sw x 1” FPT
0020-233
1” M Sw x 1” FPT
0020-230
1” Sw T
0109-003
1/2”Thermowell
0020-198
1/2” Ball Valve
0020-195
3/4” F Hose x 1/2”
0020-270
1 1/2” Street 90 0020-271
1 1/2”Tee
0020-271
1 1/2”Tee
0020-272
1 1/2” x 1/2”
Reducer
Circulation
Pump
(Not Included)
To furnace hot
water supply
Return from
buer tank
Supply to
buer tank
To expansion tank
To furnace cold
water return
To furnace drain
Water
Flow

14 Flex Fuel Owner’s Manual March 2011
5: Installation
Expansion Tank
Since the Flex fuel is a non pressurized system, an expansion tank is needed to allow the water to
expand when heated.
The Expansion tank should be connected to the furnace through 1” line and should be placed higher
than the top of the furnace. (See Diagram On Page 11)
Your expansion tank should be sized according to the total amount of water in your system. for every 150
gallons of water in the system, there should be room for 5 gallons in the expansion tank. Do not over ll
your expansion tank as it may overow when the water in the system heats up and expands.
Note: The expansion tank must be vented so that the system will not become pressurized.
There MUST NOT be a valve between the expansion tank and furnace. Failure to vent the furnace
may result to damage to the furnace and/or severe injury or death.
Expansion Tank Kit
The following images shows the basic layout for attaching the site tube and vent cap to your expansion
tank. Installation is the same for both the 10 and 20 gallon tanks. Ensure that the vent is properly used
and that the system is not allowed to become pressurized.
The Expansion tank must be placed higher than the top of the furnace. Ensure that the mounting
location is capable of supporting the weight of the tank plus the weight of the water when completely
full. The sight tube can be on either the right or left side of the expansion tank.
Horizontal Orientation
Expansion Tank (20 Gallon Shown)
0020-247
1” Blk St 90
0020-247
1” Blk St 90
0020-250
1” x 2” Blk nipple
0020-140
1” Pex x 1” MPT
1” Pex Line
1” Pex Line
1” Pex Line
0020-142
1” x 1” Pex
Crimp 90
0020-145
1” Pex Crimp
Ring
To Furnace
0020-273
Vent Cap
0020-145
1” Pex Crimp
Ring

15
March 2011 Flex Fuel Owner’s Manual
5: Installation
Expansion Tank (20 Gallon Shown)
0020-247
1” Blk St 90
0020-247
1” Blk St 90
0020-250
1” x 2” Blk nipple
0020-273
Vent Cap
0020-140
1” Pex x 1” MPT
0020-140
1” Pex x 1” MPT
1” Pex Line
1” Pex Line
1” Pex Line
0020-142
1” x 1” Pex
Crimp 90
0020-142
1” x 1” Pex
Crimp 90
0020-145
1” Pex Crimp
Ring
0020-145
1” Pex Crimp
Ring
To Furnace
Vertical Orientation
Expansion Tank Kit (020-0008)
Part No. Description
0020-273 Vent Cap
0020-250 1” x 2” Blk nipple
0020-247 1” Blk St 90 (2)
0020-140 1” Pex x 1”MPT (2)
0020-142 1” x 1” Pex Crimp 90 (2)
0020-145 1” Pex Crimp Ring (6)
0020-044 44” of Clear 1” Pex
Note: Contents are the same for both horizontal and vertical layouts.
Buer Tank
The size of the buer tank is determined by the size of the furnace. Recommended buer tank capacities
are approximately 165 gallons for the Flex fuel 30 kW running only on pellets, and approximately 300
gallons if bulk materials are to be used. Approximately 285 gallons is recommended for the Flex fuel
60 kW running only on pellets and approximately 600 gallons if bulk materials are to be used. Dierent
congurations are available depending on your application. Tanks are available in 165, 220, 285 and 550
gallon sizes. Please contact your WoodMaster Flex fuel Dealer for further assistance. Additional water
storage will increase time between lls if you are running bulk materials. Your buer tank should be
insulated.

16 Flex Fuel Owner’s Manual March 2011
5: Installation
Buer Tank Kit (020-0009)
Part No. Description
0020-140 1” Pex x 1”MPT (2)
0020-145 1” Pex Crimp Ring (2)
0020-189 1 1/4” x 1”Reducer (4)
0020-195 3/4” F Hose x 1/2”
Part No. Description
0020-197 1” FPT Ball Valve (6)
0020-247 1” Blk St 90
0020-250 1” x 2” Blk Nipple (5)
0020-260 1” x 1/2’ Reducer
Part No. Description
0020-622 1/2” Plug (2)
0020-623 1 1/4” Plug (4)
0109-003 1/2”Thermowell (2)
Buer Tank Kit
The following images shows the basic layout for attaching the Buer Tank Kit to a buer tank. This
process remains the same for all buer tank sizes. Each buer tank will require its own Buer Tank Kit.
The kit supplies all necessary attachments to properly set up your buer tank as well as proper venting
and draining. Additional line may be required to extend the drain. Adapters may be purchased through
your WoodMaster Flex fuel Dealer for using this buer tank with 1”Pex line or 1” copper line. The tank
should be installed by a qualied plumber. All Threaded ttings require the used of thread seal tape or
pipe dope.
Buer Tank
(Not Included)
Buer Tank
(Not Included)
0020-197
1” FPT Ball Valve
0020-197
1” FPT Ball Valve
0020-197
1” FPT Ball Valve
0020-250
1” x 2” Blk Nipple
0020-250
1” x 2” Blk Nipple
0020-250
1” x 2” Blk Nipple
0020-189
1 1/4” x 1”
Reducer Bushing
0020-189
1 1/4” x 1”
Reducer Bushing
0020-189
1 1/4” x 1” Reducer Bushing
0020-189
1 1/4” x 1”
Reducer Bushing
0020-623
1 1/4” Plug
0020-623
1 1/4” Plug
0020-623
1 1/4” Plug
0020-623
1 1/4” Plug
0020-622
1/2” Plug
0020-622
1/2” Plug
0020-197
1” FPT Ball Valve
0020-250
1” x 2” Blk Nipple
0020-197
1” FPT
Ball Valve
0020-250
1” x 2” Blk Nipple
0109-003
1/2”Thermowell
0109-003
1/2”Thermowell
From Furnace Supply
To Furnace Return
To Heating Zone
From Heating Zone
To Buer Drain
To Buer Bleed Valve
1” Pex Line
(Not Included)
0020-247
1” Blk St 90
0020-140
1” Pex x 1” MPT
0020-145
1” Pex Crimp
Ring
0020-140
1” Pex x 1” MPT
0020-260
1” x 1/2”
Reducer
0020-195
3/4” F Hose x 1/2”

17
March 2011 Flex Fuel Owner’s Manual
5.5 Electrical Connections
Note: Be sure to follow all local, state and federal guidelines. Wiring installation should be preformed
by a qualied electrician.
Main Power Connection
Your Flex fuel needs a 120 V connection with a 20 amp circuit for the basic unit.
The unit must be properly grounded to ensure proper operation. Failure to properly ground the unit will
result in a voided warranty.
Secondary Power Connections
Secondary power connections include a pump, igniter (optional) and the pellet arm (optional).
Main Circulating Pump
Your Flex fuel comes with the proper wiring harness and connections to power a pump at the rear of the
furnace. Pump wiring must be done by a qualied electrician.
5: Installation
Filling the Furnace and Buer With Water
Your Flex fuel furnace should be lled with clean drinking water that has minimal water impurities. Do
not ll your furnace with water from lakes, rivers, ponds, etc.
Your Flex fuel furnace can be lled with water by adding water to the expansion tank above the furnace.
Ensure that you leave enough room in the expansion tank for when the water is heated to avoid water
from spilling over.
The buer tank(s) should be lled from the bottom of the tank. while lling the tank the valve on the top
should be open to vent the air out of the system. Once all the air is out of the tank close the top valve.
It is necessary to monitor and bleed o any excess air that may be in the system once the furnace is
operational. However do not try to bleed the buer tank while the pumps are running. Any air in the
furnace will self bleed into the expansion tank.
Boiler treatment must be used with all water types and system congurations. Antifreeze can be added
to systems that have components that may be subject to freezing if the furnace is not run for an
extended period of time. Boiler treatment must still be used even when antifreeze is present in the
system.
Setting the Diverting Valve
Your furnace requires a return water temperature minimum of 140°F during operating. Adjusting the
valve is a one time process during the initial firing. Start the process by having the valve at the
maximum setting. Start adjusting when the bottom of your buer tank is below 130°F and the furnace is
above 150°F. Adjust the valve down and monitor the water temperature on the display. Once the furnace
display reads between 140°F and 150°F for the return water temperature the valve is adjusted properly.

18 Flex Fuel Owner’s Manual March 2011
5: Installation
5.6 I/O Board
Pellet Auger
Room Feed Auger
Vibrator
LAMBDA
CIRC Temp
Stack Temp
Stove Temp
Supply Temp
Return Temp
Intake Auger Temp
Display
TRIAC FUSE 10A
Draft Inducer
Solar Pump
N L
SPARE FUSE 10A
Secondary Air
Primary Air
Main Circulating Pump
BB Pro
Gate Motor
Igniter
Heat Exchanger Clean
Ash Extraction
PE N L TK TK
FOT
Secondary Heat Source Extra SCP
Storage Tank
Storage Tank Pump
Stove Pump Heat 2 Heat 1 Mixer 2 Mixer 1
N L N L N L N L N L N L N L1 L2 N L1 L2 N L
COM
POWER
DI Temp.
Draft Inducer Speed
Bin Switch
Reverse
SPARE FUSE 10A
NO C NC
NO C NC
MAIN FUSE 10A
120 VAC 60 Hz
EXP Bus
Outside Temp
Storage Tank Temp 2
Storage Tank Temp 1
Flow Temp 2
Room Temp 2
Stove Temp 2
Room Temp 1
Flow Temp 1
Solar Panel Supply Temp
Solar Panel Return Temp
Solar Panel Temp
Call FS
10
11 12 13 14
21
1 2 3 4 5
1 2 1 2 3
7
8
18
1
2
3
4
5
6
9
15
16
17

19
March 2011 Flex Fuel Owner’s Manual
5: Installation
Flex fuel 60 kW Flex fuel 30 kW
# 4
Main Circulating Pump
Connections

20 Flex Fuel Owner’s Manual March 2011
5: Installation
5.7 Connecting to Heating System
Existing Forced Air
A water to air heat exchanger is inserted in the existing plenum. In most cases the heat exchanger is placed
in a horizontal position, keeping all four sides level. The air must be forced through the nned area of the
heat exchanger evenly. The hot water line coming from the hot-water tube enters the bottom tting of the
heat exchanger and exits the top tting, which returns to the furnace. If the plenum is too large or too small,
it must be altered to t the heat exchanger properly.
Note: The Water to Air Heat Exchanger must be installed below any existing
O-Peak electric coils already in the plenum.
After the installation of the WoodMaster add-on water to air exchanger, the air ow may need to be in-
creased to fuel furnaces, electric furnaces, and electric/gas furnaces. Contact your dealer for assistance.
Existing Hot Water Heat
A Water to Water Heat Transfer Unit is used to connect to an existing hot water boiler system.
Note: Any changes that are made to an existing boiler should be done by a qualied
plumber and follow all state and local codes.
Hot Water Supply from Flex fuel
(Always put supply in lower port.)
Cold Water Return to
Flex fuel
Hot Water Supply from
Flex fuel
Cold Water Return to
Flex fuel
Existing Heat
Zone Return
WoodMaster Water to
Water Heat Transfer Unit
Circulating Pump
for Existing Hot
Water Heating
System
Existing Hot
Water Boiler