New Fisher Stove Owner

[Todd67]

The 36 inch clearance was required when the stove was built. NFPA came up with 115* f. over ambient temperature as the benchmark maximum surface temperature which is used by UL. So at 70* room temp, combustible materials surface temp cannot exceed 185*. The testing is done with thermocouples mounted on moveable walls. Stove is over fired with oven dried softwood stapled together in bricks called "Firebrands". This is what determines clearances. Not the manufacturer.

What makes it more dangerous is TIME.
When first installed, the moisture content of building materials is high, with high ignition point temperatures. The longer it is dried over time, the lower the ignition point becomes. If you take a piece of wood and continue to dry it under your stove for a period of time, you will find you can light it very easily. Just like charcoal from the rear of the stove that is raked forward. All the moisture has been released, and it will burst into flame very easily when raised to the temperature of the coals.

The only thing I see wrong in your picture is the window trim and sill, possibly less than 36 inches to stove surface.
When burning at your maximum temp, see what temperature the wood is. This will give you an idea how close it comes to the 115* over ambient benchmark. I use an IR thermometer all the time to inspect cases like this. Check the cats and dogs temps too. Amazing how hot stove dwellers can get.

Thanks for the detailed explanation!

That window trim was a concern for me at first, but these windows are so drafty that the window trim stays cold, well under 90*. When the wind blows outside, the curtains and blinds move inside. As for the animals, they're always warm to the touch

 

[bholler]

Thanks for the detailed explanation!

That window trim was a concern for me at first, but these windows are so drafty that the window trim stays cold, well under 90*. When the wind blows outside, the curtains and blinds move inside. As for the animals, they're always warm to the touch

Does that stone wall have a ventilated air space behind it?

 

[Todd67]

Does that stone wall have a ventilated air space behind it?

Yes it does. The frame for the hearth is metal 2x4 studs. The metal floor studs are placed on the floor to raise the hearth 4" above the floor. The metal wall studs are laid flat against the wall to create a 1.5" air space between the drywall and the stone wall. I have two layers of 1/2" durrock cement board on the floor and walls of the hearth, with all seems staggered. The top of the stone walls is open to allow air to flow behind and under the hearth.

I did all the work myself. Here is the link to that project that I documented on this forum in 2012...

Mama Bear restoration and installation project

I was planning to install the Baby Bear this year and the Mama Bear next year but we decided to go ahead and ditch our pellet stove and install the Mama Bear instead. The Baby Bear will get installed next year. The Mama wasn't in bad shape but we removed all rust and replaced all firebricks...

www.hearth.com

 

[bholler]

Yes it does. The frame for the hearth is metal 2x4 studs. The metal floor studs are placed on the floor to raise the hearth 4" above the floor. The metal wall studs are laid flat against the wall to create a 1.5" air space between the drywall and the stone wall. I have two layers of 1/2" durrock cement board on the floor and walls of the hearth, with all seems staggered. The top of the stone walls is open to allow air to flow behind and under the hearth.

I did all the work myself. Here is the link to that project that I documented on this forum in 2012...

Mama Bear restoration and installation project

I was planning to install the Baby Bear this year and the Mama Bear next year but we decided to go ahead and ditch our pellet stove and install the Mama Bear instead. The Baby Bear will get installed next year. The Mama wasn't in bad shape but we removed all rust and replaced all firebricks...

www.hearth.com

Good. Where is the bottom gap

 

[Todd67]

Good. Where is the bottom gap

The far left and right of the hearth, under the windows

 

[bholler]

The far left and right of the hearth, under the windows

It should be all the way across the bottom

 

[Todd67]

Maybe I don't understand what you are asking. The entire area under the hearth is built to allow air to move throughout the space under and behind the hearth.

 

[Todd67]

The hearth is so thick with 1" of cement board and the 2" thick patio paver stones on top of that, there's no way there's any real heat under the hearth, if that is a concern.

 

[bholler]

Maybe I don't understand what you are asking. The entire area under the hearth is built to allow air to move throughout the space under and behind the hearth.

Your wall shielding needs to have a 1" gap all the way across the bottom to let the cooling air in. Without that it is not a proper ventilated wall shield and you get no clearance reduction. I am not telling you this to be a pita. I am telling you this because you are giving people advice and to do that you should know the proper way to do things. Your install is better than most and is probably perfectly fine. But if I was called in to do a real estate or insurance inspection without that Gap at the bottom I would have to lable it as non code compliant.

 

[Todd67]

Your wall shielding needs to have a 1" gap all the way across the bottom to let the cooling air in. Without that it is not a proper ventilated wall shield and you get no clearance reduction. I am not telling you this to be a pita. I am telling you this because you are giving people advice and to do that you should know the proper way to do things. Your install is better than most and is probably perfectly fine. But if I was called in to do a real estate or insurance inspection without that Gap at the bottom I would have to lable it as non code compliant.

Thanks for the information! I did months of painstaking research of codes and laws and I never saw anything about a bottom gap. Otherwise I would've included it in my hearth. I'm not saying it wasn't mentioned, but I never saw it mentioned.

Can you post a picture of a hearth with a bottom gap so I can see what you are talking about?

 

[bholler]

Thanks for the information! I did months of painstaking research of codes and laws and I never saw anything about a bottom gap. Otherwise I would've included it in my hearth. I'm not saying it wasn't mentioned, but I never saw it mentioned.

Can you post a picture of a hearth with a bottom gap so I can see what you are talking about?

It is all there in the nfpa 211 description of a ventilated wall shield. An common sense tells you if you want air to circulate behind that panel you need to let air in as well as our.