Grandma poor efficiency ??

[Dave K]

Hi all, new to this forum and figured I'd share my experience after reading lots of good info. Any way, I just currently got my hands on a real nice fisher grandma bear stove. Been running it for about a month now and recently just installed a baffle and door gaskets. I know these stoves don't require any gaskets but I was getting a lot of leakage around the doors. Now that these upgrades were installed I have noticed a much longer burn time and a lot less smoke. Now I have to leave the intakes just a tad open cause if there all the way shut the fire will just about go out. I used the flat tape style gasket in the channel on the stove. My baffle is 5/16" x 22 1/2 " x 10 " have a 2 1/2 " gap just a bit more surface area than the 8 " exhaust. We'll see how it goes. So far so good. Thanks for all the great info.

Thanks for sharing. Do you have any pictures of the baffle? My Grandma II didn't come with a baffle and I've got to get one in there soon. I would love to get longer burn times

 

[Dave K]

Dave;
It should look just like the one pictured above. That is factory with angle iron welded to the sides. The bricks you set it on will vary depending on if there is a second brick course in the stove. Early in the thread I pictured angle iron welded to a plate to prevent side support bricks from falling inward if you don't have the second course and need to place bricks on the retainers to support it.

And people with single door stoves would love to watch their fire...... That's the efficiency trade off having your fireplace stove. A deep stove with 6 inch pipe and flue is the answer to longer burns. (once you're sure there are no air leaks at door seals and chimney is sized / insulated correctly) BTW I don't see a damper in your avatar, I assume you have one in the vent pipe? I always ended up with too many coals and charcoal in the back after a few days burning 24/7. I would have to open it up and get the pile flaming to get rid if it for room to load during real cold weather. I always remove a little ash from the front where it burns out in the morning and rake some of the pile ahead. Close damper and air almost fully for the day, and by 3 PM remove any ash from the front and rake ahead to reload. Open air and damper and it takes right off. Every few days there is enough coals and charcoal to do that. Since that is our only heat source, I try to burn the coal pile down on warmer or at least sunny days since it won't heat like a load of wood when full of coals. I remove a little ash each day to prevent letting it go out to clean ash.

Thanks Coaly. I actually don't have a damper at all. I assume that's a contributing factor to my short burn cycles? I probably should add one. I'll have to search the site for info on how to do that.

 

[coaly]

Your installation instructions require it. If you burn with a screen in place it is your only control.
Is this stove connected to a flue the same size as stove outlet, 8 inch round?? If larger, that's another place your fuel is going.
If the doors don't seal well as I described in the test above, you could slow it down with the damper...... with no damper you're basically uncontrolled.
The flue size and chimney type will determine your damper setting. Among other things like barometric pressure and temperature when you get it fine tuned.

I moved your post to your own thread since your problems are off topic of a baffle instal.

In the first pipe section, you drill a hole the size of damper rod, take damper apart, get the feel of putting the damper together with two hands, then put it in the pipe and instal the rod. Quite simple. The handle gives you an idea of damper plate direction. Depending on the flue size and how much heat you need to leave up, dampers have different size holes in the center. New ones only have small holes next to the rod. They need to run open farther. Older ones will have a larger hole to meter the amount when closed fully. Another lost art I suppose.........

 

[Dave K]

Your installation instructions require it. If you burn with a screen in place it is your only control.
Is this stove connected to a flue the same size as stove outlet, 8 inch round?? If larger, that's another place your fuel is going.
If the doors don't seal well as I described in the test above, you could slow it down with the damper...... with no damper you're basically uncontrolled.
The flue size and chimney type will determine your damper setting. Among other things like barometric pressure and temperature when you get it fine tuned.

I moved your post to your own thread since your problems are off topic of a baffle instal.

In the first pipe section, you drill a hole the size of damper rod, take damper apart, get the feel of putting the damper together with two hands, then put it in the pipe and instal the rod. Quite simple. The handle gives you an idea of damper plate direction. Depending on the flue size and how much heat you need to leave up, dampers have different size holes in the center. New ones only have small holes next to the rod. They need to run open farther. Older ones will have a larger hole to meter the amount when closed fully. Another lost art I suppose.........

View attachment 144050

Thanks for the reply and directions on adding the damper. I just saw that this now has its own thread. My flue pipe diameter is 8" and the exterior clay tile lined chimney is 8" as well. I've burned for a full season without the damper and didn't have any problems (and the previous owners must've been burning for 30 years without one). The seal on my door is quite good (according to the dollar bill test). How far up on the first section do I want to put the damper?

I swept the chimney on Wednesday (first time it was swept since last November) and got about 3/4 of a gallon of powdery stuff. No stage 3 creosote at all.

 

[coaly]

As close to the stove as possible and wherever it's comfortable to reach. A 6 inch pipe section made with damper in it goes right on the stove. This is what was sold with the stove when purchased as a "complete installation kit". The part is still available from Dura-Vent at Home Depot. Far cheaper to add your own in the first section of pipe. An IR thermometer or at least a stove pipe thermometer is a must so you know what you're doing.

Yeah, I gave you your own thread since it's not baffle related. (yet)

I always tend to overdo kindling, so when it gets ripping and you know the flames are out of the stove in the pipe, I close the damper partially to keep the heat in the stove where you want it to ignite the larger stuff. The damper slows velocity in the stack. With air dampers spun open a few turns you can hear it throttle down by closing damper, yet giving it all the air it needs to get going. I couldn't imagine using any Fisher without a damper. I've always had interior insulated chimneys and could run half closed or more. The larger the flue, and colder as in masonry or exterior chimney, the more open you have to run it. Installing a baffle plate isn't the same as a damper. A baffle changes the flow in the firebox, burning off more smoke and directing heat to stove top. It will decrease flue temp slightly, so it changes your damper setting. If you baffle your stove, you may be able to run wide open damper, but it's still required to have one for open door burning with screen in place.

With screen in place and an established fire, close the damper partially until you see smoke at the top collect and want to roll in. Open slightly and that is the setting for slowing the fire without causing smoke to come in. The colder it is outside, the stronger the draft and the more you can close it. With doors open, that is your only throttle and the reason the manual calls for one. With doors open in fireplace mode, it is not considered a radiant heater.

You're doing real good creosote wise, so with a damper you want to check it monthly to have an idea how much you create running it 1/4 , 1/2 or 3/4 shut. I'm sure with that little accumulation for a year you can save a lot of heat from going up before getting excessive amounts. Take note how many more coals or glowing mass you have in the morning. And don't forget to ALWAYS open damper fully when opening stove doors. That is something you're not used to doing and you're going to open the doors to a puff of smoke until you get used to it. Where you run your damper is a variable thing depending on outside temperature and barometric pressure.

 

[Dave K]

Excellent info. I plan on putting a damper in for sure.