I like Lopi stoves. They are efficient and clean burning. The combustion air comes in the at the center bottom of the unit but unlike most other stove the air does not go directly into the combustion chamber. It flows through a passage on the floor of the firebox. Then it goes up a passage on the back wall where it splits into two and then runs along the top of the firebox, until it reaches the front corners where it flows down through two channels in the corners which then join in the center at the front of the firebox near the door, and finally enters the combustion chamber. At that point the combustion air is very hot and when it hits the fuel it makes an efficient flame.
But that is not all. Here is where the reburner comes into play. The smoke does not go straight up the flue. At the top of the firebox there are 2 stainless steel air distribution tubes that are constantly being heated by the fire below. Clean, heated combustion air is introduced into those tubes where it is mixed with the smoke from the firebox. Any unburned particles or combustion products are burned there and then move out the stack after moving across a tortuous path to extract heat.
On startup the bypass is opened and the unit starts (and smokes) like a normal stove. Once it reaches operating temperature, 5–10 minutes, you close the bypass and the unit starts the reburner. With a thermal imager you can see the temperature rise when the reburner kicks in. There is no smoke coming out of the stake. None, zip, zilch! All you see are heat waves.
All this complexity produces a unit with an efficiency in the 70% – 75% range! .A good single stage stove with a nice firebox and a baffle runs in the 40% range.
I like to keep my Lopi running at ~700F. At that temperature it produces (measured by me) about 40,000 BTU/hr. They say it will put out 70,000 BTU/hr, probably at 1000F, but I don’t run mine that hot.
I selected a stove with a reburner for 2 main reasons. The catalytic converter stoves need to have their converters serviced or replaced occasionally depending upon the quality of the wood use. You are not supposed to burn junk. I stayed away from those.
The reburner at 700F will eat anything without leaving a lot of ash or creosote! (Don’t do this. Ignore advice from people on the internet, Your mileage may vary. Keep away from children. Did I make enough disclaimers yet?) The high temperature of the air and firebox effectively pyrolyzes the wood and the gases burn in the reburner tubes on top. They sit there and glow! I toss in all kinds of stuff, pizza and wings night – the boxes and bones go in the4 stove. newspapers, mail, old cooking oil, animal fat, – it all goes in and disappears. You can toss in a dead cat and it will burn. I even start the stove with a small shot of motor oil left over from oil changes. I figure as long as the stove it burning it is effectively making oil.
I check my flue regularly and it has been clean ever since.it was installed ~8 – 10 years ago. I use single wall, corrugated stainless that runs up the center of my chimney . The unit and installation was a bit expensive at a price of $4400 at that time. But it has paid for itself many times over. in heating oil saved. Plus, it pays me to exercise when I work outdoors and clean up any downed trees. Pine, apple, basswood, hickory… It all goes in the firebox.
Here’s what I don’t like.
1) My stove is an insert and sits floor level in the fireplace. Loading wood is difficult, I need to sit on the floor to position wood. No big deal. It is exercise.
2) The firebox is 24” wide and 16” deep. But the corners are cut off so it is almost impossible to put in a large piece of wood that is actually 24” long. You really need to stay below 22” when you are cutting. Also the firebox has so many passages and reburning tubes in it, it is not possible to stuff it with enough wood to last for more than 8 hours. Figure 6 hours is the max. If you get up the pee at night this timing is perfect.
At the other extreme I have a monster Glacier Bay from the early 1980s in my basement. It will take a log 36” long and 12” in diameter! Any pieces that won’t fit in the Lopi are burned in that one . I can stuff it and it will run 12 hours. But it is inefficient and dirty – and needs clean wood.
3) The intake air adjustment is too sensitive. (Remember, mine is 8 years old so they probably fixed this by now.) It has a slide that covers and uncovers the air intake port. Pull it a little bit and the stove idles, pull it more and it seems like wide open. I marked mine with high temp paint so I can set it repeatably.
4) The unit is an insert, so it needs a fan to circulate the air efficiently. Air is drawn in at the bottom front and is expelled across the top and sides. It is a beautiful concept, but if you lose power you need to have a battery backup to keep the fan going. Also the fan makes noise. The sound is irritating when watching TV. By the way I put heat sinks on the top of my stove to suck more heat out.
5) The glass door is gorgeous and the fire looks great when it is clean. But the door glass gets dirty and looks messy after a few hours of burning. You have to clean it if you want it looking nice for company.
Also the glass is, well…, glass and is fragile. A friend of mine loaded his stove and slammed the door to keep a piece of wood from falling out. Unfortunately the wood hit the glass and broke it. Air rushed into the firebox and he had a very hot fire until he managed to put it out with a large fire extinguisher.
My information is a little old but wood stoves don’t change as quickly as iPhones and Andriod devices. You should check out their site to get the latest and greatest info.
One more thing Lopis are made in USA and their customer service is excellent. I called up with a question and spoke to someone right here in the US who quickly sent me the part I needed. (What was my problem? I was using my thermal imager and noticed a small “cool” spot in the glass near the seal around the glass edge. They sent me a new gasket which was quick and easy to replace. Fixed.)
Product detail page for the Freedom Wood Insert