Earth Stone Mystery

Greetings! I recently purchased a 3 season cabin and in it is an Earth Stone model 100. I had never seen one before and was taken by its design and size. In fact, my first thought was, "this thing is so big that it will be way too hot in here. I'll have to replace it with a smaller stove." But I was wrong! In fact my very first stay at my new cabin, I couldn't get the room temperature past 30F degrees. Granted it was about -10F degrees outside, and there is only insulation in the ceiling. Regardless, I burned the stove for 3+hours full tilt and despite the huge wood box, and all the wood I fed it, it just wouldn't get the job done. I was surprised so I began to do some research. (thats how I found you all ) I examined the stove as it operated and observed that the flames and the heat were going right up the chimney. The 7 inch opening for the chimney pipe is more or less right over the wood box. I know this stove was made before EPA standards and so isn't very efficient, but it seemed like something wasn't right. How could they make a stove work so poorly.

Sorry for the long winded explanation.... here comes the mystery....

When the stove was cold, I did a thorough examination. I vacuumed all the ashes out and checked the back vent. I checked the chimney... all good. Then I saw it.... the two angled "posts" welded to the back wall of the firebox. What in the world are those for, I thought. Then I noticed that the height of the top of the posts was exactly even with the two ledges on both sides of the box. Hmmmmmm??? this cant be a coincidence. These posts must be to support something... but what?

DOES ANYONE KNOW WHAT THESE POSTS ARE FOR????

I concluded, right or wrong, that there was a part missing. I went online and searched photo after photo and everything I could read about the stove, including the manual. I was flabbergast that there was no evidence of anything on these supports! or any missing components. But I convinced my self that these are in fact supports. Then I got the idea that if I put a piece of 1/2" steel 25" X 14" this would sit perfectly on the ledges and supports. The steel would then create a barrier from the box to the chimney ( a wood box top, if you will), causing the heat to travel "up and around" the steel shelf and then "back and up" the chimney. This would help keep the gases in the box longer, giving the gases a chance to burn in the box and not go up the chimney, and it would delay the heat from exiting the stove. The shelf, being 1/2" thick also would act as a heat sink. Would this work??? Well, only one way to find out! So I got the steel cut to order for $60 (who knew steel was so expensive!) and I put it in place. It was a bear to get in. I had to angle it and it is quite heavy. But I got it. It fits perfectly and.... I believe it has made a huge difference! At first I got a little smoke in the house as the chimney air was cold, but once the air started to flow up the chimney with the heat of the fire, the smoke was no longer an issue. I may pull the steel and cut one inch off the length making it only 13 inches. This would reduce the likely hood of smoke coming in. As the smoke rises to meet the steel shelf, it then "flows" toward the front of the stove where some of it leaves the box and enters the house. Most of it goes up over the edge of the steel and then back over the top of the steel and up the chimney. The heat makes a sort of serpentine path now, instead of going straight up.

I've attached a few pictures of the stove operating with my steel shelf in place. So my questions for this forum are:
1. What the heck are those posts for?
2. Do you think my work around is sensible or is the improvement I noticed from the "placebo effect"?
3. Would a stove pipe damper do the same thing?
4. Are there any other ways of making my stove more efficient?

Thanks for you thoughts on this and sorry for being so long winded!

PS If nothing else, I think the shelf could be used as an oven shelf for heating rolls or making a wood-fired pizza! LOL

 

Thanks for the welcome Eric. I can say with certainty that they are not for secondary air delivery. They are simply welded to the back wall. They arent a conduit to any air intake.

 

Welcome to the club, Moose Pond !
Glad you found us!

WeldrDave may be able to give you some info on adding a baffle to a non-EPA stove.

 

Welcome Moose Pond glad to meet ya! I am sure you'll get all the answers that you need, there's a lot of knowledge on this site!

 

I have a well used Earth Stove in my house. I am able to heat about 3/4 of of my 1700sqft house with it. It does burn a lot of wood. Mine has two tubes in the back wall as well that act as air intakes and are connected to the dial on the side, and the box on the back that has a rod that moved up and down to adjust the air flow. Hopefully my rambling makes sense!

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Be gentle while loading or whenever you open the door. It will crack at all four corners of the fire box opening.

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Also..

judging by the pic you posted, for me to get any real heat especially just a couple hours after a cold start I would need twice that much wood burning and split a little smaller preferably. I live in the middle of lower Michigan and average a face cord a week during the cold months

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Thanks all for the input. I will definately check on the idea of the tubes being attached to the bimetalic thermostate box. I may owe you an apology Erik. You suggested a secondary air intake as a possible function and I said I was certain that isn't the case! If Flint is correct, then I am wrong! I'm going to peruse this theory for sure. And... I got to thinking... while the posts are exactly the same level as the side ledges, they arent at all necessary to hold up my steel shelf! The shelf is completely supported by each side ledge! So while the tubes provide a "third point" of support, it isnt necessary at all. In other words, if the pipes weren't there, the steel wouldn't notice! Ill keep you posted. Thanks for the advice about the door cracking!

 

Thanks also for the advice on the amount of wood to burn. I did in fact have a lot more wood in it, but when I took the picture I had already started "winding" it down as I was leaving soon. But Ill be sure to feed that big dog next time!

 

Next fire you could slide the steel forward till the chimney heats up and draws then return it to its original position. Should stop the smoke on cold starts

 

You're right! An excellent Idea! It should solve that problem! Ill give it a go and report back.

 

You meant to tag Coaly right?

 

The baffle plate is supposed to be sitting on the angled supports on that angle.
You can't have it horizontal.
First, that causes flame impingement. That is when flame tips come into contact with something and causes them to give up their heat. It cools what is called the "burn zone". it also slows velocity up flue which is what causes air to move into stove, which is why you have less heat output.

The plate should be 5/16 thick, this is a critical thickness that allows the plate to heat correctly like the heat range of a spark plug. It ignites smoke particles that come into contact with it. Too thick will run too cool, too thin will burn and warp.

Baffle size was designed for the worst case scenario chimney, (larger flue used from an existing fireplace) so the customer had no problems with smoke roll in when opening doors. Best size chimney flue is the same as stove outlet. You need to make the opening where smoke travels over baffle the same square inch opening as square inch opening of flue. This will allow the correct amount of heat to escape up flue. I call that opening "smoke space" adjustment and is critical to adjust for chimney and connector pipe resistance, NOT the stove.

The angled baffle does 2 things. It allows smoke to be rolled back down into flames and create turbulence in firebox for better mixing of oxygen with flammable gasses being expelled from wood. There is a thread on another wood stove website where I designed the baffle plate for single door Fisher Stoves that has much more detailed information. It would literally be writing a book here. It is a tested design by Fisher that reduces particulate from 60 grams of particles to 6 for every kg. of fuel burned. designed originally to reduce smoke, it make the entire stove much more efficient.