The Longwood dual-fuel, wood-burning furnace was manufactured years ago, but many are still in operation. This site will serve as a central source of information about the Longwood.
For those unfamiliar with the Longwood, it is a dual-fuel furnace and is meant to operate on wood and another fuel - either oil, natural gas, or propane. The manual indicates that when properly set up it will operate efficiently as a dual-fuel unit, switching back and forth between wood (as long as supply is maintained, of course) and the other fuel automatically, as needed to maintain temperature.
The furnace is large - about 6 feet long overall - as it is designed to burn 5 foot long logs (hence the name), and it is capable of putting out a substantial amount of heat.
Send me additional information and experiences you have and I'll post it here for the benefit of all. Email me at RRDDTM@gmail.com.
Note: I am curious if anyone has converted a Longwood into an outdoor wood furnace. Send me details if you have.
As always, heating with wood carries risks. If you're new to this I recommend talking to someone who has burned before, or a professional. As always, follow all installation recommendations for clearances, etc. Use an appropriate chimney. Check with your insurance company.