Kicks Out Up To 90,000 Btu

The WoodMaster LT90 furnace is ideal for heating multiple buildings, including an office building or workshop.

Reduced Price! Contact your local dealer for more information.

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Financing Available

Colors & Specs

  • Black
  • Charcoal
  • Brown
  • Green

Custom colors: Contact a wood furnace dealer

LT90 specifications:

  • Fire Box 34″ x 32″
  • Door Size 16″ x 16″
  • Thickness: 1/4″ fire drum & water jacket
  • Draft Control: Fan
  • Overall Size 7′ x 5′ x 6′
  • Heating Capacity 90,000 Btu
  • Total Water Capacity 120 gallons
  • Limited Lifetime Warranty
  • Shipping Weight 1,800 lbs.

Heating area may vary depending on construction, insulation and climate.



No fuels enter the house to limit smoke, soot, fire hazards and the risk of dangerous carbon monoxide buildup


Designed to deliver maximum Btu for more usable heat with less wood cutting and furnace-filling time

WoodMaster exclusives:

Round chamber design provides optimum internal air movement and water circulation for even heat transfer and more efficient burn. This design also offers:

  • Forty percent fewer seams than a square box, for less chance of cracking or leaking and minimal pitting
  • No dead spots, so creosote doesn’t build up


Outdoor wood furnace maintenance tips:

  • Manage combustion by keep a continuous supply of oxygen and using the proper amount and type (cut, seasoned) of fuel (wood)
  • Properly build fires:
    • Completely open the damper
    • Place paper/kindling over entire bottom of fire box
    • Never use flammable liquids
    • Warm the flue
  • Inspect chimney flue, stovepipe every month
    • Look for cracked liners, missing parts, bird nests or other hazards
  • Clean joints, chimney connectors and flues as necessary
  • Maintain a briskly burning fire to reduce creosote buildup
  • If you do have a chimney fire, inspect and repair weakened parts before restarting furnace
  • Properly, regularly dispose of ashes

Owner’s Resources

Download Manual


WoodMaster WarrantyLT90
600 Polk Ave. SW – Red Lake Falls, MN 56750
Toll free (800) 932-3629 or (218) 253-4328

Five Year Limited Warranty on Fire Drum and Water Jacket
Northwest Manufacturing, Inc. of Red Lake Falls, MN 56750 warrants material and labor on any defects in workmanship on the Fire drum and Water Jacket for a period of five years from the purchase date to the original owner only. If there is a leak in your properly delivered and installed WoodMaster furnace in the first year, WoodMaster will replace the furnace at no cost to the original owner. (A leak means; a leak in the firebox or water jacket.) Northwest Manufacturing, Inc. will not be responsible for environmental conditions we cannot control. After the fifth year Northwest Manufacturing, Inc. provides no other warranty.

This warranty is limited to defective parts – repair and/or replacement only, and excludes any incidental and consequential damages connected therewith. Northwest Manufacturing, Inc. is not responsible for replace-ment of water, water treatment, antifreeze, costs of transportation, or shipping charges. On sight service work will be offered to you. Please call Northwest Manufacturing, Inc. for current non-warranty rates.

WARNING: Northwest Manufacturing, Inc. will not warranty the inside of fire drum due to ash corro-sion. Rotation of ashes must be taken care of as displayed on the maintenance list, located on the side of the furnace. The fire drum must be completely cleaned of all ashes and creosote a minimum of two (2) times per year, preferably half way through the heating season and immediately after the heating season. The chimney must be covered when the furnace is not in use. If antifreeze is not being used the water jacket must be drained and flushed yearly after each heating season. After the furnace has been drained, immediately refill completelyand treat with new boiler treatment.

One Year Warranty On All Other Components – Parts And Labor
Northwest Manufacturing, Inc. warrants to the original owner only, any components in the furnace that is defec-tive during normal usage for a period of one (1) year from the date of purchase. This includes, but is not limited to all electrical, front and rear doors, siding, roof, insulation, and chimney. Parts will be replaced on an even exchange basis. Your dealer may charge you for a service call to do warranty work.

These warranties apply only if the device is installed and operated as defined in the Owner’s Manual.

WoodMaster outdoor wood furnaces are not intended to be the only source of heat; therefore a backup system should be in place to prevent any damage caused by lack of heat.

Damage caused by abuse, accidents, improper installation, overheating, corrosion, freezing or negligence will not be covered under warranty. Damage caused by burning flammable materials (such as petroleum products) will not be covered under warranty.

Antifreeze – Only nontoxic antifreeze is acceptable. Antifreeze will break down over a period of time and there-fore should be tested annually. Always dispose of antifreeze by state and local codes. Loss of antifreeze underany condition will not be covered.