Wood Heat

GARN Videos

GARN Video Channel
GARN Overview
GARN JR. Introduction
First Hour Burn
Ernie's GARN
Ernie's GARN Revisited


GARN Brochure
GARN Thermal Storage Advantage
Garn Website
Garn Installation


Advanced Wood Heat
Salmon Arm, BC.

Key words

A Masterpiece of Simplicity

GARN has proven itself to be the most durable wood boiler in the industry with an unmatched history of longevity, reliability and efficient performance. With only 2 moving parts, the door and the fan, the GARN is a masterpiece of simplicity and reliability.

The GARN Wood Heating System can be sizeded to heat residential, commercial, or agricultural applications. When installed in tandem, multiple GARN units can be used to heat multiple building, large commercial and public facilities such as arenas, schools or hospitals.

See How a GARN Works.


Announcing the latest addition to the GARN family
the1000 gallon GARN JR.


New Emissions Report

In March/April 2011, a production GARN WHS 1500 unit was tested by Intertek Testing, an independent test laboratory.

The results of this independent test are:
***.13 lbs of particulate/million BTU’s delivered
***3.91 grams/hour year round particulate rating
***80.5% delivered efficiency

The emission results are 57% less than the current EPA Phase II Limit of .32 lbs of particulate per million BTU’s delivered. This emission result is also 73% less than the commercial limit of .60 lbs of particulate per million BTU’s delivered.

Click to see the full emissions report:

The GARN line of Wood Heating Systems (WHS), have been an integral part of developing wood as a viable, clean, and effective renewable, carbon neutral heating source. The GARN WHS line of wood-fired hydronic heaters combine high-efficiency wood combustion and hydronic thermal storage to make the most efficient and effective wood heating units on the market.

Two-Stage Combustion ensures low emissions so there is virtually no smoke, creosote, or ash. *Smokeless because approximately 15 minutes after starting a fire, your GARN unit burns so efficiently, that little smoke is produced!
Five-Pass Heat Exchanger ensures efficient combustion heat transfer into thermal storage.
Integrated Thermal Storage allows heat to be drawn off as needed between burns.
Water-Based Delivery ensures efficient transfer of the stored heat to the building or application.
Easy Integration with radiant floor, hot water baseboard, cast iron and European style radiators, forced air furnaces, or other heating systems allows the units to be added into existing applications or new construction.

GARN units are certified by independent lab tests to comply with all applicable UL and CSA Standards, and are the only wood-fired hydronic heater certified for both horizontal and vertical flue venting. Our boilers are certified to burn cord or slab wood; pallet and other scrap wood; dense wood briquettes; and air dried corn on the cob.

GARN® WHS Technical Specifications
Model WHS 1000 WHS 1500 WHS 2000 WHS 3200
Tested Efficiency (LHV)* 80% 80% 88.4% 85%
Particulate Emissions rate – PM2.5 4.4 gr/hr 2.87 gr/hr 1.65 gr/hr Not Tested
Width in Inches 67" 72" 72" 86"
Height in Inches 65" 75" 75" 93"
Overall Length in Inches 88" 111" 135" 172"
Recommended wood Length 16"-24" 24"-32" 24"-32" 32"-48"
Recommended wood Diameter 3" to 10" 3" to 10" 3" to 10" 4" to 12"
Weight Empty in Pounds 2,200 3,550 3,980 7,500
Weight Filled in Pounds 8,150 15,400 19,000 34,500
Approx.Storage in Gallons 980 1,420 1,825 3,200
Firebox Length in Inches 36" 41" 41" 50"
Firebox Diameter in Inches 24" 25" 25" 40"
Btu's Stored (120°-200°) 540,000 920,000 1,272,000 2,064,000
Btu/hr Max. Heat Output 180,000 250,000 325,000 700,000
†Maximum heat output is based on reloading once every 3 hours with 24 inch long split white oak, with 20% moisture content. Output rate is fuel dependent and will vary with wood type, moisture content, size and reloading frequency. GARN® WHS units are certified safe to burn cord or slab wood, densified wood briquettes and air dried corn on the cob.
*Tested to ASTM-E2618
GARN units comply with all applicable UL and CSA safety standards, and because of their low exhaust temperatures, are the only wood-fired hydronic heaters certified for both horizontal or vertical flue venting in the United States. Our units are certified to burn cord wood, slab wood, pallet and other scrap wood, dense wood briquettes, and air-dried corn on the cob.

How it Works.

Combustion air is drawn directly from outdoors through an internal air inlet tube (A) to the air distribution collar (B). The outdoor air is preheated as it travels through the air inlet tube (A) and the air distribution collar (B). This yields more efficient combustion.
A compliant seal on the loading door (C) prevents room air from entering the combustion chamber (E). The loading door is insulated to prevent heat loss and includes an air-cooled heat shield to minimize hot surfaces near the user.
Combustion air from the collar (B) flows through upper and lower nozzles (D) into the combustion chamber (E).
Additional air from the upper nozzle is mixed with hot gases from primary combustion before entering the ceramic secondary combustion chamber (F).
Within the ceramic chamber, smoke, creosote and particulates are burned in a very turbulent, horizontal gasification process at temperatures near and above 2000 ºF.
After exiting the secondary combustion chamber, the hot gases are drawn through a 5-pass tubular heat exchanger (G) transferring their heat to the water in the tank.
The cooled gases are then drawn into the Draft Inducer Fan (H) and pushed out of the exhaust pipe (I) at temperatures less than 350 ºF.

garn firebox garn whs 1500 Horizontal flue

Features and Benefits
Features Benefits
•Integrated Combustion •Safe and Certified to be Installed Indoors
•Non-Pressurized Thermal Storage •No Overnight Loading or Fire Required
•Double Weld Construction •Long Life, Low Maintenance Construction
•Secondary Combustion (Gasification) Chamber •Reduced Wood Use
•5 Pass Heat Exchanger •Easy to Load Fuel Chamber
•Large Insulated Loading Door •Cool to the Touch Loading Door
•Double Lock Safety Handle •No Smoke in Your Face when Reloading Fuel
•Hot Water Return (HWR) Dispersion Tube •Easy Maintenance
•Manway Access •Simple Part Replacement
•Induced Draft Fan •Anodes with Water Treatment Minimize Corrosion
•Air Cooled Door •Demonstrated Longevity
•Combustion Air Supplied from Outside •Available Electric Backup
•30 Years of Proven Technology


Advanced Wood Heat
Salmon Arm, BC.
PH. 250-515-1106