End of Season Clean Out - Rear Liner Burn Thru Clayton

Did my prep for off season hibernation over the last couple days. Dug out all the ashes and clinkers, removed the firebrick and the front and rear liners. Wire brushed and vacuumed out all the ash. Sealed the flue breech with a plastic bag and a rubber band. Then I hosed the interior with oil to prevent corrosion and placed a 100 watt flood lamp pointing downward to keep the grates warm while also keeping the whole interior warm. I'm hoping its enough to keep the water coils safe thru summer. Took the flue pipe apart, hosed the ash out of them and let them bake in the sun all day to dry thoroughly rotating them every couple hours. Then I placed them in the attic, the driest place a can think of to store them for the summer.
I had quite a pile of mush at the bottom of my chimney where it goes vertical. Since my mid season clean out I burned some bitty coal for about 5 days. I found it has very excessive soot build up. I also burned wood for about 5 days (recently) which caused condensation in the chimney. I assume it caused the mush pile to become saturated. I don't see me burning anything but anthracite from now on You can see my chimney is choking a little bit which would explain why I was getting some smoke roll out the loading door when I needed to load fuel. That stinky slop was no joy to clean up haha.. Cold wood soot is gross smelling. My wife was complaining
My rear liner burned thru. Below is a pic of it. I'm pretty sure that the combination of stuffing insulation behind it (to prevent combustion air bypass) and burning bitty coal that went nuclear on me contributed to its demise. Its looking pretty disgusting too ..

What I would really like to do is make a rear liner out of refractory cement for next year.. Sounds like a cool summer project Any advise on what to do there?

Lightning wrote:What I would really like to do is make a rear liner out of refractory cement for next year.. Sounds like a cool summer project Any advise on what to do there?

It's hard to give advice because I don't know how that piece is held in which might limit what you replace it with.

Castable refractory is expensive, especially shipping and you have to construct some sort of mold to form it in. An alternative is a $10 pot of furnace cement from a plumbing supply which you can flesh out or extend with broken fire brick rubble and maybe some sand added.

Another way is to cut split firebrick to shape with a cheap Harbor Freight grinder and diamond blade. Cost less than $30 plus brick.

It's a tribute to your skill and patience that you have taken a badly designed stove and gotten practical results from it. Very few would have had the acumen to do that. I think we both know the real answer is to run the stove until it has given you adequate payback and then to replace it with a better design. Run the stove but keep a sharp eye on the used market for a bargain, especially now in the summer season.

franco b wrote:It's hard to give advice because I don't know how that piece is held in which might limit what you replace it with.

The firebrick that lay along the "V" shape of the firebox go up against the rear liner. If you look at the rear of the firebox in the above picture you can see how it sat vertically along that back wall just above the grate. It doesn't seem to have any purpose other than keeping the hot coal away from contact with the back wall of the firebox AND to provide secondary air from the primary air source. (I already have an independent secondary air inlet in the back of the furnace. Its where a combustion air blower is designed to go for wood burning I assume.) The rear liner doesn't really hold anything in place...

franco b wrote:Castable refractory is expensive, especially shipping and you have to construct some sort of mold to form it in. An alternative is a $10 pot of furnace cement from a plumbing supply which you can flesh out or extend with broken fire brick rubble and maybe some sand added.

How expensive say 20-30 pounds worth. I was planning a mold made out of some scrap plywood. I'd rather not attempt bothching something together .. Although I did consider cutting some square brick to fit back there but was afraid I had no way to hold it in place since it will stand vertically.

franco b wrote:It's a tribute to your skill and patience that you have taken a badly designed stove and gotten practical results from it. Very few would have had the acumen to do that. I think we both know the real answer is to run the stove until it has given you adequate payback and then to replace it with a better design. Run the stove but keep a sharp eye on the used market for a bargain, especially now in the summer season.

Thank you for the kind words partner .. I agree, been looking at other furnaces but I must admit, I'm not quite sick enough of this one yet .. I enjoy the challenges I guess.. And shes done good keeping us warm

Nice job on the clean out and prep. I assume either side is lined with firebricks that you removed already and that rear plate serves nothing other then to allow air up through the grates to flow behind the burning coal bed? (why that area might be taking the brunt of the heat because the air is flowing towards that rear end moreso then the middle or front maybe?), In any case... as you know already, you don't need that bypassing air if your burning anthracite anyways so I agree... just make a plywood mold the shape you need, clue it up or shoot it off off with a finish gun then brush a crapload of oil in the mold with an old brush and dump in your mixed up batch of refractory (buy the smallest bag you can), you don't have to worry about friction, wear or the make up of the refractory with this unit... You got the right idea bro

Lightning wrote:I enjoy the challenges I guess..

That's good and the forum has benefited from the insights on coal burning those challenges have given you.

A cheap easier fix on that plate is just to bolt a piece of heavy steel or much lighter stainless steel over that hole.

I think 10 pounds of Rutland castable is about $25 plus maybe $15 shipping. Enough for 144 cubic inches. You can try Amazon for prices.

franco b wrote:

Lightning wrote:I enjoy the challenges I guess..

That's good and the forum has benefited from the insights on coal burning those challenges have given you.

A cheap easier fix on that plate is just to bolt a piece of heavy steel or much lighter stainless steel over that hole.

I think 10 pounds of Rutland castable is about $25 plus maybe $15 shipping. Enough for 144 cubic inches. You can try Amazon for prices.

I think he wants to stop the bypass airflow though, and wisly so, even a heavy gauge 1/4" think steel plate would prolly warp to heck in that position and the plate would cost more then the rutland (I almost gasped at the price of steel when I went to have a simple baffle made )

dcrane wrote: and the plate would cost more then the rutland (I almost gasped at the price of steel when I went to have a simple baffle made )

Buy? You get it at the dump free.

Yeah Doug has the right idea. I wanna prevent the air flow behind that plate and figured a solid mass of refractory brick would do the trick while at the same time protect the back of the fire box

Heres a pic of the back plate in the furnace before it burned thru.. The sides of the firebrick goes up against it as they lay on the sloped sides of the firebox. I was looking at castable refractory cement to make a plate out of. Heres what I found

http://www.grabcart.com/product/Home-and-garden/C ... 2-1-2-lbs-

Is this what I should use?

That should do it. If the form is open than cover with plastic for a few days to dry slowly.

franco b wrote:That should do it. If the form is open than cover with plastic for a few days to dry slowly.

Thanks franco! I just did the math.. Area of a trapezoid = 1/2 height x (base1+base2)
Height is 9 inches, across the top is 20, across the bottom is 12

A= 1/2 (9 inches) x (20 inches on top + 12 inches on bottom)
A= 1/2 (9) + 32
A= 144 square inches

That 12.5 pound bucket will make a 12x12 inch block 1 and a quarter inch thick (144 sq inches)

How convenient haha

Did I do that right ?? I was hoping not need 2 buckets of it...

And should I put a few rods of 1/4 inch steel thru it for reinforcement?
It will turn out a bit wide on top and not very thick..
I don't know how heat expansion would work out though..
I wouldn't want any reinforcing bar to expand and break it apart either..

That's funny, I got the same answer as you, 144.

It seems logical to reinforce with steel, but consider that the rods will surely be at 1000 degrees and have the strength of wet spaghetti. I don't think I would. Cracks can be mended with retort cement which is used very thin. Do pay attention though to curing the cement well for maximum strength.

You could also consider casting in two pieces with a thin steel divider down the middle when casting. If you do that be sure to grease the divider for easy removal. Each half will be stronger. The divider could be inserted after pouring and striking off so it need not have any fastening.

You might even consider making a pattern and having a piece cast of iron from your closest foundry.That way you could make it as thick as you deem practical.If you decide on a foundry option don't forget to include the shrink rate for cast iron in your measurements. Good Luck . Mike

stovepipemike wrote:You might even consider making a pattern and having a piece cast of iron from your closest foundry.That way you could make it as thick as you deem practical.If you decide on a foundry option don't forget to include the shrink rate for cast iron in your measurements. Good Luck . Mike

But would a piece of solid iron protect the back wall from too much heat??
Thanks for your suggestion....