Cabin Stove Sizing

WV Cabin Posted By WV Cabin, Jan 11, 2018 at 7:50 PM

  1. WV Cabin

    WV Cabin
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    New member, I have a Grandma Bear that came in our 54o sqft off grid cabin, it runs us out even when it’s -10 out side. I am looking at replacement with a PAPA Bear. I was wondering about putting the secondary air in to the top chamber, will it adversely effect burn time or actually help?
     
  2. Don H

    Don H
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    Seems to me if you're being run out by the Grandma Bear then getting a Papa Bear would be moving in the wrong direction. According to the manual a Papa Bear heats 2,000 sq. ft., a Grandma Bear heats 1,500 sq. ft. Of course how well insulated the building is, ceiling hight, chimney design etc. effects how well a stove will heat.

    Check the chart on page 1.
    https://www.hearth.com/images/uploads/Fisher_Manual.pdf

    For 540 sq. ft. you might want to look at a Baby Bear (1,000 sq. ft.) or a Honey Bear (1250 sq. ft.).
     
  3. WV Cabin

    WV Cabin
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    My mistake, we have a Grand Pa bear after more looking at the pictures, I agree with the size, we need a baby bear and I am looking for one now. I guess I just need to play with it to control the heat with out under firing it.
     
  4. WV Cabin

    WV Cabin
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    Does any one have a ballpark stove top and flue minimum temp to fire my stove at? The man we bought the cabin from gave me some basics on it but he was generating a lot of creosol in the flue. The set up is a top flue 8” to 6” stove pipe with a 4’ vertical rise to a 90 (for clean out) then 4’ horizontal through wall to a 24’ vertical 6” double wall to cap above peak. It drafts great but looking to tune the heat out put till I can locate and install a Baby Bear. Thanks in advance.
     
  5. coaly

    coaly
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    The object is to keep the flue gasses above 250* to the top when smoke is present.
    Below that water vapor will condense on the flue walls allowing smoke particles to stick. That is creosote.

    Make sure the horizontal pipe is pitched uphill toward the chimney at least 1/4 inch per foot.

    If you use your stove for cooking and water heating like I do in my cabin, you want a Mama Bear for a larger cooktop.
    If the cabin is solid logs with no insulation in the walls, Mama Bear is needed since heat loss is greater and that construction relies on the mass of logs to absorb heat. If it is cold when you get there, you also want the next size larger than if it were heated constantly. It takes a long time to bring a log cabin up to temp and radiate back inside if that is what you have.

    Your description of pipe and flue sounds like you have a through the wall pipe with exterior chimney up the side of building and not through the roof correct? Is this single wall pipe inside and Class A insulated chimney sections outside?
     
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  6. WV Cabin

    WV Cabin
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    440C8054-4309-4190-8B12-FBCEC465EC5E.jpeg DEA0B79B-737B-4D70-8213-8C4DE8248C56.jpeg
    Coaly,
    Yes that is correct, single wall heavy gauge stove pipe inside and double wall outside. I will try to up load pictures. The picture of the flue is just at start up. I can get him to burn clean, Some have thought the fire was out cause of lack of smoke but once the Cabin interior comes up to 72 it runs right up to 88.
     
  7. coaly

    coaly
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    The original owner was probably using the flue damper too much. it's difficult with a larger than necessary stove since you tend to run it in a closed down condition and this is the reason for proper stove sizing.

    Put a pipe thermometer on the pipe where it connects to the through the wall thimble. Double the reading will give you flue gas temp entering chimney. Then figure heat loss to the top. (guessing 300 on a warm day, maybe 350 on a very cold day to drop to 250 at the top?) An IR gun checking flue wall temp near the top is the easiest accurate way. Outdoor temp and wind are all factors to consider.

    That system should be double wall inside and later manuals required it on any through the wall installation due to horizontal run cooling flue gasses as well as more chimney outside requiring more heat to keep hot. So depending on the model year of stove it is required by code to install as per manufacturers installation instructions. It is to reduce creosote becoming a safety factor. The smaller the stove, the more important this becomes since you don't have as much heat to lose. You can see how a Baby Bear running hard with damper open to allow lots of heat up the stack runs out of extra heat to radiate into the building. Another good reason to go with a Mama Bear. You're sizing the stove to the area you're heating as well as the chimney.

    You certainly should have double wall inside for a smaller stove, as well as if you baffle it.

    When you install double wall pipe, you must use a probe type thermometer through the double wall into the inner pipe.
     
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  8. WV Cabin

    WV Cabin
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    The cabin is all wood plank harvested and cut off the land, walls have R-30 in them, floor is wide 6”x1” board but not insulated yet. It is on a crawl space (posts) the attic is another 500 sqft that we are in the process of insulating it R-19/13 cause thats what I had, windows double pained, with plans for the very top at the ridge to get R-30.
    Coaly,
    Thanks for the info, I will change the pipe when I find a smaller bear to put in mines place. I have ordered a thermometer and I have a IR gun I will take when I go back after the snow season. I like the large tops on the stove we have as does the wife for cooking on from time to time. What would be the best fit in your option for the Cabin? It’s construction is as follows,The cabin is all wood plank harvested and cut off the land, walls have R-30 in them, floor is wide 6”x1” board but not insulated yet. It is on a crawl space (posts) the attic is another 500 sqft that we are in the process of insulating it R-19/13 cause thats what I had, windows double pained, with plans for the very top at the ridge to get R-30. He had it wrapped in vinyl before he sold it to me.
     
  9. warburtonplayer

    warburtonplayer
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    I have a baby bear arch door and heats my 1450 square foot house with no problem.
     
  10. WV Cabin

    WV Cabin
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    Thanks
     
  11. coaly

    coaly
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    Yes, a Baby Bear is fine for enough heat, as long as you have other cooking and hot water facilities.
    The double door models have next to no cook top, so maybe you would be fine with a Baby. I don't have a water heater or other cooking at my off grid cabin, so I need the larger cook top. An oven needs at least a Mama Bear top. I went with a rear vent to cook on lower level and set oven on the top.
    I assume your configuration would be best with a side vent.
     
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  12. WV Cabin

    WV Cabin
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    Thanks,
    I will be looking for a baby bear or momma bear, I do have propane stove/oven and instant propane water heater. I have solar and a wind turbine (need to reconnect to battery bank), also have pole power to 3 outlets if needed. Water is spring feed, I have also learned I need to stock pile more wood and get it drier. Thanks for all you insightfulness on here. I have been reading over everything I see in here to try to get smarter quicker.
     
  13. coaly

    coaly
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    Here's my shower. I heat the water in a wash tub on the Fisher and pour it over myself as it drains quite well through my front porch floor. !!! The neighbors can only see me with my shirt off and run the other way knowing what I'm doing. That's a cabin.

    front Porch 12-2012 2.JPG P1010045.JPG
     
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  14. WV Cabin

    WV Cabin
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    Very cool, got a line on a Momma Bear, trying to set up a look see tomorrow. End goal is get little cabin set up and functional, clear a
    Designated spot on property (40 acres on side of mountain) and build ranch style cabin for retirement. Per profile same age, getting a late start at it but ain’t afraid of work. Question, on the silver I see on the trees and such making em pretty are they using high temp silver? I did 22 yea in the navy and the stuff we used on the boilers never dried “forever”.
     
  15. coaly

    coaly
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    Yeah, just high temp paint. It dries just like black or any other color.
    I know what you mean by silver boiler paint. I was a steam mechanic on locomotives and we had this silver used on the smoke box (all the way up front at the end of the tubes) and it was like baked on silver anti-seize that never dried! It was Government owned National Park Service that used any left over military stuff they could. Slimey stuff it was.
     
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  16. WV Cabin

    WV Cabin
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    Yep, still work in the power industry and high temp Anti Seize hasn’t changed any. If I can get a momma bear for my Cabin I think I read some of the stoves had a water option or am I mistaken? I was thinking of piping a hot water tank to it with a double or quad pass through the top of the fire box.
     
  17. coaly

    coaly
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    No factory water coils.
    Use that anti seize on hinge pins and reach through the intakes on doors from the back to brush it on the intake knob threads. That's the two movable parts that will show any wear on these stoves.
     
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  18. WV Cabin

    WV Cabin
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    Will do thanks, going to look at a flat top Momma Bear tomorrow.
     

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