I was looking at wood burning fire place inserts to help off-set the high cost of heating our house next winter. They don't look to complicated to build. Steel, fire bricks and a blower. Has anyone ever fabricated one or have plans to for one?
"richard" wrote: (clip) Has anyone ever fabricated one or have plans to for one? ^^^^^^^^^^^^^^^^^ I built one once for some to give as a gift. No bricks and no blower. It was made from scrap pieces of exhaust pipe. The bottom portion acted as a fire grate. Air entered each pipe from the room and got heated as it passed back, up and forward again, to reenter the room at the top/front of the fireplace. It actually made the room TOO warm (but this is California.)
"richard" wrote: I have seen them for sale on E-bay, only the ones for sale had small blowers on the inlet of each pipe to help circulate the air. I talked with the local fireplace vendor about them and he said they were good, but a lot of heat still goes up the chimney. ^^^^^^^^^^^^^^^ I think a blower increses the efficiency somewhat, but the vendor is right--some heat still goes up the chimney. But not nearly as much as does without the heat transfer tubing. It is actually possible to have the fire produce a draft up the chimney which draws air from the room and produces a net loss of room heat.
Friends of mine in a remote hill home had a fireplace that was constructed of flagstone, with air passages that circulated air over the outside of a metal firebox--it heated the house really well. Good for them, because they would otherwise have had to use bottled gas or electric heat.
Take a ride up to Georgetown Fireplace. Spend some time talking with them and looking at their fireplace inserts. They are pricey but have good products. I bought a woodburning stove from them years ago and have been happy with it.
No plans here only knowledge gained from using one.
I suggest making one 100% steel with the execption of maybe glass window in the door.
Make it hollow. Outside wall with correct dimensions to fit inside the fireplace. Inside wall size will determined be the amount of gap that you decide to have between the outside and inside wall for the heating air jacket. I am guessing at least 1 to 2 inches.
Also have the same thing with regards to the top of the firebox. You will have to make an hole for smoke discharge and an damper. Damper slides in and out horizontially. The dishcharge hole should be sealed to not allow mixing smoke and heated air in the heating air jacket.
Bottom of the firebox, only the bottom. Not sure about if there is an airgap between the bottom and the fireplace.
At the bottom on both sides, there is an electric fan intake for cool air to be blow thru the heating jacket. It uses an electric fan for each side, there is slot above each fan and one above the doors for heated air discharge. The top heated air discharge has a long overhang sort of looking thing above it. It is heavy steel also, well it is at least 1/8 inch thick, Length of it is a bit longer than the double doors.
It has one adjustable switch for both fans. The switch is a rotating type with infinite adjustment. No steps or notches for speeds.
Make sure that you make a large enough false front for it to where you can seal off the fireplace around it to keep the smoke out of the house.
I can not give much more specific information about it at the moment as we are using it right now keeping the house warm. Do not remember the size or shape of the smoke discharge.
The only things that are not steel are the cast iron round air intakes on both doors, the brass balls mounted on it, the electric fans, switch and wiring. It does not have glass inserts in the doors. Wish that it did.
We have have some 9 degree nights here in Texas, the insert kept the heater from kicking in. It got to 80 to 90 degrees sometimes in the living room when we stayed with keeping the fire fed and rolling. Had fans moving the heat to the rest of the house.
Hate to throw a wrench in making your own insert, but your might want to check with your insurance comoany first - a fire at you house whether from the insert or something else may not be covered. Sucks , doesn't it.
a comeercially made and EPA/Underwrithers approved may be cheaper in the long run.
Make sure your plan does not pull to much heat from the fire. If the air is to cool going out the chimney creosote will form. I have seen chimneys that incorporate things like this to help recovery of heat.
I should have said that also that this a commerical made unit. It is over 25 years old. Company is out of business.
I looked up inside the firebox this morning for the first time in years, It has close to the roof of the firebox, round tubing running from the back to the front of the insert. The smoke discharge hole is recantgle in shape at rear of the firebox.
Where I live, it is illegal to even re-install a wood stove that is not EPA certified for clean burning. Insurance companies are very interested in such things. A properly designed stove burns much cleaner than old designs, resulting in less creosote buildup and more efficiency. Check craigslist for a used insert. I got a used, certified insert and stainless chimney liner for $350. Maybe I was lucky, but that was a lot easier than modifying my old one for a liner and better efficiency.