Wood master LT 90 User manual

Outdoor Wood Fired
Hydronic HEater
LT 90
LT SERIES OWNERS MANUAL
Retain this manual
Northwest Manufacturing, Inc / 600 Polk Ave SW / Red Lake Falls, MN 56750
www.woodmaster.com / 800-932-3629 / Manual PN: 7994-590
Rev: 3.1

2LT 90 Owners Manual 2015
Safety.................................................................................... 3
Fuel ....................................................................................... 4
Features ................................................................................ 5
Installaon ....................................................................... 6-10
Operaon....................................................................... 11-12
E.T.C. Reference .............................................................. 13-19
Maintenance .................................................................. 20-21
Wiring Diagram .............................................................. 22-23
Troubleshoong .................................................................. 24
Warranty ........................................................................ 25-28
Specicaons ...................................................................... 29
Notes ............................................................................. 30-31
Thank you for purchasing a quality
wood furnace from WoodMaster.
This product was designed to de-
liver easy, trouble free operaon
for years to come. Check out other
WoodMaster heang products at
www.woodmaster.com, or our line
of quality pellet grills at
www.woodmasterpelletgrills.com.
Table of
Contents

3
LT 90 Owners Manual
2015
• Read and follow these direcons carefully. Retain this manual for as long as you own your LT 90.
• All installaon and operaons must follow STATE and LOCAL CODES for wiring, and ring of this
unit. These CODES may dier from this manual. Installaon must be performed by a qualied installer.
• Follow the manual carefully. Follow the recommended cleaning and maintenance.
• The WoodMaster LT 90 is designed to be operated in a open system. Make sure all necessary
safety components are installed and funconing properly. DO NOT pressurize the LT 90.
• Freeze protecon must be guaranteed in all water-bearing parts in the event of extensive idle
periods of the system. Note: Your WoodMaster LT 90 is not intended to be your only heat source.
• Boiler water treatment must be used to ensure proper water quality.
• The chimney height may need to be adjusted depending on the installaon and local codes. Do not connect
this unit to a chimney ue serving another appliance. Follow all state/local codes.
• Never open the tube access door during operaon!
• Never operate any part of the system with covers, shields or panels removed.
• Anyone who is not familiar with and/or has not been trained to operate the LT 90 may not
operate the system. Only responsible adults should operate your LT 90. If the LT 90 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 or any other part of the system.
• Always keep the area around, and in front of the system clean and free from combusble materials.
• Keep animals away from the system.
• The operaon may not be connued or restarted in the event of visible damages (for example,
thermal distoron, traces of smoke or re, mechanical damages, etc.). Any damages must be repaired.
In the event of any doubts, please contact your authorized WoodMaster dealer.
• The 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 E.T.C. and door handle during the operaon. Temperatures at other points (for example,
chimney, tube access box & door, water lines…) can be very high.
• The WoodMaster LT 90 must be operated exclusively according to the guidelines for planning,
assembly, regulaons, statutes and product related instrucons. The manufacturer is not liable for
damages and their results, if they occurred due to improper assembly, operaon, applicaon and also
inadequate maintenance and cleaning.
• Disconnect all electrical power to the LT 90 before performing any service.
• The water pump must run connuously whenever the WoodMaster LT 90 is being used.
Safety

4LT 90 Owners Manual 2015
Safety
Fuel
• Never shut power o to the LT90 if there is a re and fuel in the rebox unless there is an emergency.
• Take the proper precauons to ensure that the modicaons made to an exisng heang system does not
interfere with exisng safety controls.
• Never use the following: trash, plascs, gasoline, rubber, or naphtha in your WoodMaster LT 90.
• Read and follow these direcons carefully. Retain this manual for as long as you own your LT 90.
Sweeping
The chimney should be inspected and cleaned as needed, typically twice a year. This is to be done by qualied
persons. Shut o the furnace, disconnect power and allow the system to cool before aempng to clean the
system.
Warning!
Always disconnect the power to the furnace before any cleaning or maintenance. Service agreements increas-
es operaon length and life of the unit. For more informaon contact your local WoodMaster dealer.
Replacement parts should only be genuine Northwest Manufacturing, Inc. components. Your dealer can supply
the genuine service parts and install them.
All fuels must conform to certain quality standards to ensure trouble free operaon of the furnace. Use
of unapproved fuels may result in faulty operaon and a voided warranty. Never use the following: trash,
household garbage, plascs, gasoline, rubber, naphtha, leaves, and materials treated with petroleum prod-
ucts (ie: parcleboard, railroad es & pressure treated wood). Newspaper and plain, unprinted cardboard
should only be used as kindling, not as fuel. Other paper products should not be used. Please contact your
WoodMaster dealer for any quesons on fuel use.
Only cut, split, seasoned wood with a internal moisture content of 25% or less may be used. Wood can be cut
to a maximum length of 27 inches. The wood should always be placed horizontally and parallel to the rebox
wall. The pieces of wood should be stacked as ghtly as possible whereby the face of the wood should NOT
touch the rebox wall. This ensures proper air ow. DO NOT burn any large, round pieces of wood. DO NOT
burn any “green wood”, or any wood that is above the 25% moisture limit.
Water Content
The maximum permied water content is 25%.
Bark Content
The maximum permied bark content is 20%.

5
LT 90 Owners Manual
2015
Front View
Rear Panel
Hanger Strap
Night
Light
Safety Sckers
Fuel
Door
Stainless Steel Chim-
ney
Vent Cap
E.T.C.
Panel
Maintenance
Schedule
Serial/Model
Numbers
Primary Return
(Cold)
Water Temp Snap
Disc
Thermistor
Probe
Primary Supply
(Hot)
Drain
Dra Inducer
Heat Exchanger
Clean Out
Secondary Return
(Cold)
Solenoid
Combuson
Fan
Secondary Supply
(Hot)
Features

6LT 90 Owners Manual 2015
Choosing Locaon
When installing your WoodMaster, keep in mind the direcon of the winds during heang months. Try to place
the furnace in an area where exhaust will not be a problem for yourself or any surrounding neighbors.
LOCATION: It is recommended that the unit be located with due consideraon to the prevailing wind direcon.
• When using more that 4 feet of chimney extension external support is needed.
• Should be located greater than 100 feet from any residence not served.
• If located between 100 and 300 feet to any residence not served, it is recommended that the
stack be at least 100% of the height of the peak of the residence, plus an addional 2 feet.
Always remember to comply with all applicable state and local codes.
Chimney Specicaons
To insure proper insulaon, use only a Class A Insulated Chimney and Chimney Adapter from your local Wood-
Master Dealer or Northwest Manufacturing, Inc. A dra inducer may be used to ensure proper dra under all
condions. Note: Remove the chimney cap prior to lighng the furnace. CAUTION: Using a non-insulated chim-
ney or failure to use a Class A Insulated Chimney WILL result in a voided Warranty. When using more than
four feet of chimney extension external support is needed.
Pad Supports
The LT 90 should be placed on cement
blocks. The blocks should be at least 6”
wide, 10” long and 3” thick. Two feet of
clearance from the front and rear of the fur-
nace and at least one foot clearance on the
sides is recommended. Failure to install the
WoodMaster LT 90 on a proper support will
result in a voided warranty. Never use com-
bustable materials, such as wood blocks,
to support the LT 90. A full cement pad is
recommended if the supporng ground is
so, sandy, or othewise unable to support
the furnace on the pads alone.
Residence not
served by furnace
2 feet
Residence
served by furnaceMinimum of 100 feet
Chimney height
should be 2 feet above roof line
60.00
96.00
54.00
6.00
6.00
16.00
16.00
12.00
12.00
11.50
48.00
14.00
14.00
F
FF
F
SUP
SUP
RET
RET
Installation

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LT 90 Owners Manual
2015
Trench
The trench must be 24 inches deep and 6 to 12 inches wide. It can be dug with a shovel or a backhoe. Place all
the dirt to one side of the trench to allow room for working on the other side.
Wiring
Place electrical supply in boom of trench and cover with 6 inches of dirt. Electrical wire rated for under-
ground use (14-2 +ground) can be buried in the same trench as the water lines but must maintain a minimum
24 inch depth. Always follow state and local codes.
Water Lines
The remaining 18 inches of open trench is where the water lines are placed. Use only water line approved by
Northwest Manufacturing through your Woodmaster Dealer.
NOTE: If lines travel under a driveway or where heavy equipment travels, the line should be buried two to
three feet deep. If lines travel through a low or wet area, they should be insulated and installed in a water ght
piping, (PVC).
Note: Leave a minimum of three feet of water line exposed above ground at the furnace to
insure adequate length for connecon.
Note: Before insulang and burying the water lines, label the hot water supply line at both ends. Once the
lines are covered you will be able to easily determine which line is connected to the pump.
Note: Use only approved water line insulaon sold through your WoodMaster Dealer. Poor insulaon will
cause your Wood Master furnace to burn large amounts of fuel, and hurt the eciency of the system. For
best results use high quality insulaon.
Note: Remove the chimney cap before ring your LT 45. Replace the Chimney cap when the furnace is o for
extended periods.
Note: Check the rebox and remove any accessories that are included with the LT 45 before starng the
furnace.
Installation

8LT 90 Owners Manual 2015
1” Cast Iron Pump Flange
Pump
Black Rubber Gasket
(Supplied with pump)
Hot Water Supply Va lve
Black Rubber Gasket
(Supplied with pump)
Hot Water Supply
(On back of furnace)
Direction of Flow
Indicator Arrow
1” Pex Crimp x 1” MIP
(0020-140)
1” Pex Water Line
(0020-130)
1” Pex Crimp Ring
(0020-145)
Hot Water
Supply Valves
Cold Water
Return Valves
Drain
Mounng the Pump
Note: The pump must be located on the furnace.
The pump ange valve comes pre installed on the supply
line.
Locate one of the black rubber gaskets, and place it be-
tween the pump and the mounted ange valve, bolt the
pump to the ange. Make sure the arrow on the pump
indicang direcon of water ow points down.
Bolt a 1” cast iron pump ange and gasket to the boom of
the Pump.
Note: Make sure that the pump is aached to the supply
line, not the return.
Note: A pump that has a ow rate of 10-12 GPM
is recommended
Hooking Up Water Lines
Water Supply
Aach the 1” Pex x 1” MIP ng (0020-140) to the ange
on boom of the pump. Then aach the hot water supply
1” Pex Water Line (0020-130) to the ng using 1” Pex
Crimp Ring (0020-145).
Water Return
Aach the 1” Pex x 1” MIP (0020-140) ng to the Water
Return Valve. Then aach the cold water return 1” Pex Wa-
ter Line (0020-130) to the ng using 1” Pex Crimp Ring
(0020-145).
Wiring The Pump
Remove the cover on the pump. Then using an approved wire, connect the ground wire to the green ground
screw on the pump. Connect the black wire to the yellow wire on the pump. Finally, connect the remaining two
white wires together and replace the pump cover.
Locate the juncon box in the back of furnace and remove the cover. Connect the running end of the approved
wire coming from the Pump to the Juncon.
Note: The wires from the pump will have to connect with the main power wires in the juncon box.
Note: The pump must run connuously whenever the WoodMaster Furnace is in use. DO NOT run the
pump dry.
Note: All wiring must follow state and local codes and should be done by a qualied electrician. Disconnect
power before servicing any electrical components.
This is an example of an installaon using a Taco pump. Your
layout may vary, but the pump must be on the supply line.
Installation

9
LT 90 Owners Manual
2015
Entering the building with water lines can be done underground or over the sill plate. Once inside the building
the typical hookup would run rst to the Domesc Hot Water Supply and next to an exisng heang system
such as a forced air furnace or a hot water heang system. Finally, before leaving the building, a ll valve must
be installed near a water supply for lling and ushing the boiler in the WoodMaster Furnace.
Domesc Hot Water
The Domesc Hot Water/Flat plate Kit consists of a Wa-
ter to Water Heat Transfer unit and the ngs needed
to hook it up. The unit mounts on the wall VERTICALLY
in your ulity room and is connected as shown.
Exisng Forced Air
A water to air heat exchanger is inserted in the exisng
plenum. In most cases the heat exchanger is placed in
a horizontal posion, 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 boom ng of the heat
exchanger and exits the top ng, 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 in-
stalled below any exisng o-peak electric coils
already in the plenum.
Aer the installaon of the WoodMaster add-on water
to air exchanger, the air ow may need to be increased
to fuel furnaces, electric furnaces, and electric/gas
furnaces. Methods of doing this are:
Belt Drive System
Blower pulleys and motor pulleys may be changed but
the electric current owing through the motor shall not
exceed the nameplate rang. (A blower motor of larger
power may be used.)
Direct Drive System
The motor shall not be changed, however the speed of
the motor may be increased.
water in
WoodMaster
water out
Domestic Cold
Water in
Domestic Hot
Water out
WoodMaster
The heat exchanger works on the same princi-
pal as your car heater. Air blows through the
heat exchanger, taking the heat from the water
and blowing it into your existing duct work.
Hot Water Supply from WoodMaster
(Always put supply in lower port.)
Cold Water Return to
WoodMaster
Installation

10 LT 90 Owners Manual 2015
Hot Water Supply from
WoodMaster
Cold Water Return to
WoodMaster
Existing Heat
Zone Return
WoodMaster Water to
Water Heat Transfer Unit
Circulating Pump
for Existing Hot
Water Heating
System
Existing Hot
Water Boiler
Cold Water Return from
Heat Exchanger
Domestic Water
Supply for fi lling
boiler
Cold Water
Return to
WoodMaster
Exisng Hot Water Heat
A Water to Water Heat Transfer Unit (0020-052) is used to connect to an exisng hot water boiler system.
Note: Any changes that are made to an exisng boiler should be done by a qualied
plumber and follow all state and local codes.
In Line Filter and Fill Valve Assembly
The In Line Filter and Fill Valve Assembly (0020-325) must be installed in the cold water return line before the
line exits the building. It should be placed so that a garden hose can be connected between a domesc water
supply and the ll valve.
Hot Water Supply from
WoodMaster
Cold Water Return to
WoodMaster
Existing Heat
Zone Return
WoodMaster Water to
Water Heat Transfer Unit
Circulating Pump
for Existing Hot
Water Heating
System
Existing Hot
Water Boiler
Cold Water Return from
Heat Exchanger
Domestic Water
Supply for fi lling
boiler
Cold Water
Return to
WoodMaster
Filling With Water
Connect a garden hose between a domesc water supply and the furnace ll valve (0020-325), which was
installed in the cold water return line at a point just prior to its exing the building. Make sure that valves not
being used on the furnace are closed and the valves that are being used are open. Begin lling and inspect for
leaks on all ngs. Repair any leaks that are found. The furnace may also be lled through the vent pipe in
front of the chimney.
Rounely pay aenon to the water level light. If the light is not lit, this indicates that the water level is low
and the furnace may need to have water added. Add water unl it ows out of the vent pipe. Install the vent
cap into the vent pipe once the furnace is lled with water.
Note: Place the steam saver on the furnace vent once the furnace is full.
Installation