I had some ideas on making my woodstove more effiecient and wondered if anyone had already tryied anything of the sort, and what the results migh be if they had. Installin angle iron as cooling fins on the stove pipe to glean more heat from it on its way out. Installing angle iron on the stove itself to serve the same purpose. Installing a cold air intake from outside the house so the stove isnt using warm in the house air to fire the fire- thus pulling the cold air in through chracks and seepage places. Also, along with that cold air carries more oxygen and would burn (?) hotter, or at least have the potential to (Im thinking RAM AIR cold air induction on cars- the outside air which is cooler than under hood air helps develop more HP- some where in the 7 to 10 percent range more HP developed. I also have designed a double heat reclaimer stove pipe- using 2 30 gallon drums suspended above a 55 gallon drum stove (one of which would serve as an oven), but found out they already sell this setup- well, a single reclaimer, that is.

-- Kevin in NC (Vantravlrs@aol.com), December 19, 2001

Answers

They seem like good ideas to me Kevin especially if you have good hot burning wood but if creasote is likely to be a problem I think cooling the flue will make it worse.

-- john hill (john@cnd.co.nz), December 20, 2001.

I gotta have an outside air source for my woodstove. Way back when...houses were smaller, not very tight and neither were stoves, there was alway a window close by to open a crack to get your draft going without pulling a cold draft from every corner ot the house. Now I have a pipe with a flip cap installed in the hearth. so efficient!

One of the things we used to do for more efficient heating was to put cast iron knick knacks on the stove. I used to warm my mittens by slipping them over the heads of a pair of cast iron squirrel nut crackers.

I've seen all kinds of barrel stove designs, some good, some not so good. I even saw one that looked like a locomotive and chugged like one too, until you shut her down a bit. I think if I were to have a double barrel stove, it would have the top barrel for holding water.

I think you double heat reclaimer idea is a good one. I think I saw that on a $4,000 enameled swedish made stove that I drooled on one time.

-- Just Duckie (Duck@spazmail.com), December 20, 2001.

John is absolutely right. You DO NOT want to extract heat from your stovepipe. Technically, when the gases/smoke that are moving up your stovepipe/chimney get cooler than 212 degrees F, water vapor will condense on the inside of the pipe/flue. When this occurs, creosote also condenses from a gas to a liquid and eventually dries to a flammable solid which coats the inside of the chimney flue and stovepipe. We all know that a build up of creosote can lead to chimney fires. Burning unseasoned wood or burning under "air-tight" conditions results in a "cool" fire which also leads to cool stove pipe/chimney temperatures which also results in excessive creosote buildup. My point is, the optimum temperature in your stovepipe and chimney should be at least 250 degrees F to prevent water and creosote condensation. So please, do not try to "reclaim" heat from the stovepipe unless you clean your chimney quite often. The only way to truly make a woodstove more efficient is to burn more of the fire's volatile gases BEFORE they escape up the chimney. Old models of woodstoves did nothing to slow the assent of these unburned, flammable gases up the chimney. Some stoves, like my old Fisher Grandpa Bear, had a baffle that caused these gases to recirculate back into the fire and thus be burned. Newer stoves, like my Lopi Endeavor, have a series of "afterburners" along the top of the fire box. These afterburners "inject" air into the unburned, volatile gases which causes them to ignite BEFORE they escape up the chimney. With the Lopi, I'll often see that there are no flames near the wood but there are flames dancing along the top of the firebox where the "afterburners" are located. Other brands of woodstoves use catalytic converters to burn the volatile gases before they escape up the chimney. My Lopi has an efficiency rating of over 90%. --Happy trails, Cabin Fever

-- Cabin Fever (cabinfever_mn@yahoo.com), December 20, 2001.

There are loops, rings or doughnut type stove pipe connections that can be put in line of your existing pipe that will allow more area pipe area to be in contact with the air and more air to circulate in and around the pipe. A friend of mine placed a return directly above his wood stove in the ductwork in his attic. He place a thermostatically controlled squirrel cage fan in the return. The ductwork led to the back bedrooms in his house. It kept them nice and warm.

-- Bart (Dominickwb@dot.state.sc.us), December 20, 2001.

KEVIN....THERE ARE ALL KINDS OF IDEAS TO GAIN ADDITIONAL HEAT FROM A WOODSTOVE.

[1]THE DONUTS AS SOME ONE MENTIONED IS A COMMON CONFIGURATION [2]THERE IS AN ELECTRIC HOOK UP THAT GOES ON THE PIPE CALLED HEATILATOR I BELIEVE. [3]HOOKING UP YOUR WOOD STOVE WITH A HOT WATER COIL.WOULD ADD TO ITS EFFICIENCY PLUS YOU GET FREE HOT WATER WHEN YOU HAVE THE STOVE ON. IF YOU WANT TO SAVE THE HOT WATER INSULATE THE TANK.IF YOU WANT THE HEAT TO RADIATE INTO THE ROOM FROM THE HOT WATER DON`T INSULATE IT. [4]THE METHOD YOU SUGGESTED ABOUT PIPING IN OUTSIDE AIR IS COMMON. THEY ARE CALLED EARTH TUBES.YOU HAVE A PIPE SET NEAR YOUR STOVE . IT WILL DRAW THE AIR FROM THE FLOOR VENT AND PUT LESS OF A NEGATIVE PRESSURE IN THE HOUSE BY SUCKING IN AIR FROM ALL THE LITTLE CRACKS. PLACE A SCREEN ON THE OUTSIDE VENT SO SMALL CRITTERS DON`T MOVE IN. ALL HOUSES HAVE AIR PENETRATION BUT IN CORDWOOD ITS ONE OF THE THINGS I RECOMMEND TO KEEP THE AMOUNT OF AIR PENETRATION DOWN. [5]RUN THE FLUE LONGER INSIDE THE HOUSE[IE:RUN IT UP THEN PUT ON A 90 DEGREE AND RUN IT ACROSS THE ROOM THEN 90 DEGREE IT UP AND OUT THE CHIMNEY.IN THAT RUN YOU WOULD GAIN FROM THE PIPE BEFORE THE HEAT EXITS. [6]THERE ARE FANS THAT WORK OFF THE HEAT.THEY WOULD CIRCULATE THE HEAT BETTER [7]SOME ONE SAID SOMETHING ABOUT ADDING NICNACS ON THE STOVE.HEY,I`VE GOT AN ANVIL I`M NOT USING.LOL!BUT THATS A PRACTICAL IDEA.ITS THE ANVIL THAT MIGHT NOT BE BUT IT WOULD WORK. [8]I`VE SEEN COOK STOVE MANUFACTURES TELL PEOPLE IN THEIR ADVERTISEMENT TO OPEN THE OVEN DOORS TO USE IT AS A SPACE HEATER.

TO ADD TO YOUR IDEA ABOUT ADDING FINS TO THE FLUE PIPE.WHY NOT GO WITH A HEAVIER GAUGE PIPE.PERHAPS A DOUBLE WALLED HEAVYIER PIPE WITH HOLES IN THE OUTER ONE TO RELEASE THE HEAT.IT WOULD RETAIN THE HEAT LONGER.WHAT ABOUT PUTTING BAFFLES INSIDE THE PIPE TO SLOW THE HEAT RISING DOWN.THIS WOULD BE FOR THE PIECE RIGHT OFF THE STOVE ITSELF....ITS BAFFLES IN A MASONRY HEATER THAT MAKES THEN EFFICIENT. THE BAFFLES WOULD HOLD HEAT AS WELL AND WORK MUCH THE SAME AS THE FINS.PLUS SLOW DOWN THE ESCAPING HEAT.I`VE SEEN PLASTIC PIPE WITH 1" PROTRUSIONS AROUND THE OUTSIDE OF THE PIPE.SPACED ABOUT EVERY 2".IF A FLUE PIPE WAS MADE LIKE THAT.THEN IT WOULD BE JUST WHAT YOU WANT.CREATING MORE SURFACE AREA FOR THE HEAT TO DISIPATE INTO THE ROOM. WHATEVER ANYONE DOES,MAKE SURE ITS SAFE.HAVE SOME ONE INSPECT IT.IF THEY HAVE A PROBLEM WITH IT THEN SO SHOULD YOU.

CORDWOODGUY

-- CORDWOODGUY (cordwoodguy@n2teaching.com), December 20, 2001.

I agree: don't try to cool off the flue. More creosote.

Cordwoodguy, I heated my water with my woodstove for twenty years. It was great for heating water, but in fact made the stove way less efficient. I'd recommend a wood powered water heater used only for heating water. (commercially available, or not all that hard to make, if you weld)

For efficiency, cough up the bucks, and buy an "epa certified" stove. I HAD to do this, to get a building permit, here in Orgygun. I was irritated at the government intrusion, but you know what? I'm glad they made me do it. I've got a bigger house, and use about 1/8th the amount of wood I did with my home made stove, which heated the water. I truly believe the new stove would have paid for itself in a couple of years if I were buying firewood; as it is, it has saved me a lot of work.

Mine's a Quadrafire, and I can't imagine a finer stove.

-- joj (jump@off.c), December 20, 2001.

I'm gonna say it again, because evidently it didn't sink in the first time. You do not increase the effiiency of a wood stove by adding a bunch of gismos to extract the heat out of the stove pipe. If you do this, you may cool the exhaust gases (ie, smoke) to a point where you'll get all kinds of moisture and creosote build up in the chimney because the inside of the chimney will be cooler. This can even happen with seasoned wood. The chimney needs to be hot, did you hear me? I said hot, so the moisture and creosote will stay vaporized all the way up and out of the chimney. Sometime, go up on the roof and place your hand over the top of the chimney. You'll find that the exhaust gases aren't that warm. How many chimneys and roofs have you seen with brown stains dripped down their sides? Or icicles hanging down from a chimney cap? This happens because the smoke coming out of that chimney was relatively cool and the first cold object the smoke hits caused the creosote and water vapor to condense out of it. Most wood stoves are inefficient because they do not burn all the BTU value locked up in the seasoned firewood. You see, wood fiber, doesn't actually burn. It is the gases that volatilize from hot wood which ignite and actually do the burning and create more heat. Consequently, to increase a stove's efficiency you must burn more of these flammable gases BEFORE they escape up the chimney. You can add all the doo-dads and gizmos you want to the stovepipe, but they are not going to help you increase the BTUs combusted in the stove. These lost BTUs, in the form of unburned volatile or flammable gases, will just more likely condense inside of your cooler chimney and contribute to creosote buildup. The newer stoves burn more of the BTU's locked up in your firewood and are therefore more efficient.

And never, never have more than two 90 degree elbows in your stovepipe/chimney system.
--Happy trails, Cabin Fever

-- Cabin Fever (cabinfever_mn@yahoo.com), December 20, 2001.

Who remembers that classic tune "Hot, Hot, Hot" ??

-- Rick (Rick_122@hotmail.com), December 20, 2001.

good points, cabin fever,

My quadrafire sends air under the coal bed, then out through three or four stainless steel pipes at the top of the firebox, which have small holes drilled along their length.

These pipes appear to be connected to big ol' propane tanks, as they appear to be shooting flames out of the holes; in actuality, all that's really coming out of the holes is superheated air. The super heated air combusts the gases which would otherwise go up the chimney as "smoke". The quadrafire has almost no smoke emissions, if you use good wood.

-- joj (jump@off.c), December 20, 2001.

I have utilized coiled screen door springs which you can purchase at the hardware. Just buy length which will go around pipe and hook each end together. This will transfer heat to living space without cooling chimney pipe to much. Also you can paint them with heat resistant paint to blend into pipe.

-- William Rutter (wrutter@uniontel.net), December 22, 2001.