Mama Bear help.

[jrobinson]

Hi everyone!

I moved into our new house this last winter. It came with a old "comforter" stove. It has a picture of a bird on the front. It doesn't heat really well and sometimes smokes out the top randomly. (I have no idea why)

To make a long story short. I found a great deal on a Fisher Mama bear stove. However the piping is 8 inch currently and the mama bear pipe is 6 inch. Can I use an adapter to make it work? Thanks in advance!

 

[jrobinson]

Also an fyi it is a single door.

 

[coaly]

You can, but always size a stove to the chimney.
The chimney makes the stove work. The chimney determines how much heat needs to be left up to keep internal flue temperature above 250*. That is the temp where condensation (water vapor from combustion) allows smoke particles to stick forming creosote.
Your problem is flue gasses expanding from 6 to 8 is almost double the square inch area from a 6 to 8. 2 inches in diameter may not seem like much, but square inch area goes from 28.26 to 50.25. That is a much larger area inside to heat and that's where your wood and efficiency will go. Into the chimney to keep it hot. (probably the cause of the smoke leak in your old stove not creating enough draft with enough heat left up)
A liner is needed (preferably insulated) in chimney flue the same size as stove outlet all the way up.
The chimney is more important than the stove ! It has to be right. Any newer stove is going to require 6 as well.

I just did the calculations on a neighbors chimney last night that is increased from 6 to 8. I added a baffle for better stove efficiency and used a infra-red thermometer on his pipe and chimney to see how it was going to perform.
The temperature at the 6 to 8 increaser went from 300* surface temperature to 170* !! That shows the cooling as flue gas expanded. Internal temps were from 400 to 230. That is where it dumps into chimney flue. Obviously not hot enough when allowed to increase. His would be OK with insulated 5 inch liner to prevent further cooling all the way up.