Fire safe floor grates/louvers

[MarcM]

I have a question for anyone that has ever installed and bought louvers and floor grates to allow convective flow from their stove to a room above...

I like the idea of floor grates and louvers, and the old house I'm about in to has a couple (stuffed with insulation since the second floor is not used). It seems like the only good way to get some better distribution of heat between floors with a point source heater like a wood stove.

I do have a concern, however, being a fire protection engineer, that a floor grate basically negates the compartmentalization of the room below and above afforded by the floor/ceiling assembly and provides a convenient path for fire spread. Not only that, if the fire origin is below the grate, then the residential sprinkler in that room (which it will have in the future) will not receive any convective ceiling jet flow to activate it as the bulk will be busy spreading the fire into the second floor.

I'm familiar with some fire safe louvers and smoke vents for large industrial applications, and I'd like something similar in the way of protection with the louvers, but I can't find any that are commercially produced.

Before I go through the trouble of fabrication something myself, I wondered if anyone knew of any pre made systems. What I'm thinking is it would involve louvers connected on a linkage system attached to a heavy counter weight. The weight is held up by a fusible link (just two opposing eyelets held together with a solder that melts at a nominal temperature, typically 165 or 212F). If there's sufficient heat flow through the vent to melt the solder in the fusible link, the weight drops and closes the louvers and delays the fire spread.

If this type of thing doesn't exist and anyone's interested in it, let me know, I've got a couple different design ideas floating around but nothing on paper yet.

 

[bostonbaked]

I have a question for anyone that has ever installed and bought louvers and floor grates to allow convective flow from their stove to a room above...

I like the idea of floor grates and louvers, and the old house I'm about in to has a couple (stuffed with insulation since the second floor is not used). It seems like the only good way to get some better distribution of heat between floors with a point source heater like a wood stove.

I do have a concern, however, being a fire protection engineer, that a floor grate basically negates the compartmentalization of the room below and above afforded by the floor/ceiling assembly and provides a convenient path for fire spread. Not only that, if the fire origin is below the grate, then the residential sprinkler in that room (which it will have in the future) will not receive any convective ceiling jet flow to activate it as the bulk will be busy spreading the fire into the second floor.

I'm familiar with some fire safe louvers and smoke vents for large industrial applications, and I'd like something similar in the way of protection with the louvers, but I can't find any that are commercially produced.

Before I go through the trouble of fabrication something myself, I wondered if anyone knew of any pre made systems. What I'm thinking is it would involve louvers connected on a linkage system attached to a heavy counter weight. The weight is held up by a fusible link (just two opposing eyelets held together with a solder that melts at a nominal temperature, typically 165 or 212F). If there's sufficient heat flow through the vent to melt the solder in the fusible link, the weight drops and closes the louvers and delays the fire spread.

If this type of thing doesn't exist and anyone's interested in it, let me know, I've got a couple different design ideas floating around but nothing on paper yet.

MarcM I am trying to find information on this just as you describe. I wonder if you came to a solution? I would really like to use a floor grate in my house but want to do it right. Info. please!

 

[Andy99]

Some one is selling a grate with a fusible link that closes when a certain temp is reached. I just cant remember where I saw It. I think someone might have posted it on here.

 

[begreen]

Here's a source. Google "fusible link damper" for more choices.

http://tinyurl.com/4wmu2v

 

[bostonbaked]

BeGreen, Thanks so much. If I could pick your brain a little I would like to tell you my situation. I have an old cast iron floor grate. It is wide open. The damper box is long gone. I found this one http://www.atlantasupply.com/swscri...2&STOCK_NO=12AH24X18++++++&REQUEST_ID=CSTKDET on the site you were kind enough to supply. I have never seen one of these before now. My question is can I mount this with the sleeve they mention between the floor joists under the grate and be good to go. Or do I need to have some sort of duct work to be up to snuff/code/safety standards ? I'm handy enough but just have no experience in this area as yet. Is it as simple as that and will this sleeve need to cover the surface of the joists which are only 2x8's. Do these dampers always remain full open or can they be closed manually when not needed ? I know that's a mouth full. lol Thanks

 

[begreen]

If you can sleeve the damper so that the wood is not exposed, you should be good to go. These dampers are spring loaded and stay open unless the link is broken.

 

[bostonbaked]

BeGreen, Thanks a million. The sleeves look like they are set up for instalation into a duct. If i cover the wood with sheet metal do you think that would be acceptable ? In other words make up my own metal sleve so the damper is surrounded with metal. I figure that way I can mount it down even with the bottom of the joists and make up some sort of louver that I can close right under the grate. Again thanks I can get anal about this type of thing. lol

 

[MarcM]

BeGreen, Thanks a million. The sleeves look like they are set up for instalation into a duct. If i cover the wood with sheet metal do you think that would be acceptable ? In other words make up my own metal sleve so the damper is surrounded with metal. I figure that way I can mount it down even with the bottom of the joists and make up some sort of louver that I can close right under the grate. Again thanks I can get anal about this type of thing. lol

I've seen these before, and are used quite commonly in commercial applications so fire doesn't have a path to spread through the HVAC ducting. I'd caution you to do some research into the construction of these dampers, and go so far as to suggest modifying the damper itself if you're using them in floor. From what I've seen in industry and from that link, the dampers themselves are fairly thin gauge galvanized. It would probably be enough to block fire spread to an adjacent compartment if the compartment of fire origin has a working, appropriately designed sprinkler system, but in a residence with no type of control/suppression system, I'd still want something more.

It'd most certainly be a big improvement over nothing, but I wouldn't want anyone to get a false sense of security on my account. I'm still after something that uses heavier construction, like 1/4" steel plate.

 

[Risser09]

I'm just using some of the ones that I found at Lowe's, as I don't plan on having a fire in the first place =-). Plus I think the real difference will be if I'm actually home or not in the event of a fire.

 

[MarcM]

I'm just using some of the ones that I found at Lowe's, as I don't plan on having a fire in the first place =-). Plus I think the real difference will be if I'm actually home or not in the event of a fire.

Certainly that can be the difference if you choose it to be. There are other mitigating steps one can take so that, occupied or not, your house and possesions have a good shot at surviving a fire. I suppose it depends on how much your home is worth to you. I live in a 1760's era farmhouse that is worth more to me standing than any amount of insurance money and there are some family possesions dating back to the Civil War and earlier.

Of course, there's also always the chance you'll be at home, but asleep or otherwise incapacitated...

 

[bostonbaked]

MarcM, So the big question is, What can I do ? Is there a way to beef this damper up ? If a fire started in the basement where the stove is (has to be there) I have smoke detector and carbon monoxide detector for early warning. And there is nothing blocking the hole under the grate now but a half inch of plywood. It was this way when I bought the house 14 years ago. I would think even thin metal would hold back fire longer or as long as a 1/2" of plywood. I guess you never did reach a solution in your case either ? You would think they would make some sort of unit for this application. I see quite a few people cutting vents in their floors so is there no safe way to do it ? Sorry for all the questions but every problem has a solution. I just need to find it. lol Thanks for your response and you time.

 

[Risser09]

Sorry if I'm ignorant but, what would be the greatest risk for starting a fire in a closed system like a stove with all heat shields and clearances considered?

 

[MarcM]

MarcM, So the big question is, What can I do ? Is there a way to beef this damper up ? If a fire started in the basement where the stove is (has to be there) I have smoke detector and carbon monoxide detector for early warning. And there is nothing blocking the hole under the grate now but a half inch of plywood. It was this way when I bought the house 14 years ago. I would think even thin metal would hold back fire longer or as long as a 1/2" of plywood. I guess you never did reach a solution in your case either ? You would think they would make some sort of unit for this application. I see quite a few people cutting vents in their floors so is there no safe way to do it ? Sorry for all the questions but every problem has a solution. I just need to find it. lol Thanks for your response and you time.

I've got something relatively simple worked up in my head. I'll sketch it post it sometime. I haven't done anything further because I'm not using any of the second floors in my house at this point. It's a big restoration project. There are plenty of solutions to the problem, just none that are commercially available, sounds like.

 

[MarcM]

Sorry if I'm ignorant but, what would be the greatest risk for starting a fire in a closed system like a stove with all heat shields and clearances considered?

Who said the fire has to start as a result of the stove. Doesn't matter what the ignition source is, it matters where it is in relation to your floor grate.

 

[bostonbaked]

MarcM, I have a couple of ideas myself but I'm afraid if I implement some home brew design it won't be legal. If it's not commercially made and untested and not certified then it's not going to get an ok from anyone but me. That's the rub I guess. It's an interesting problem though. I wish you well with your restoration. I love old houses and have lived in a few oldies but goodies over the years. The one you describe sounds like a real piece of history. Have fun with it. And anything you come up with I'm sure will be well thought out. Maybe someone will point us both in the right direction. I guess is ignorance is bliss because I was happy to just to pop off the plywood and go for it. The more I learn the more I worry about doing it. There seems to be a lot of opinions on this subject but I have yet to see anyone post a single definitive law or page from the fire/ building code to prove it one way or another. Thanks again.

 

[MarcM]

MarcM, I have a couple of ideas myself but I'm afraid if I implement some home brew design it won't be legal. If it's not commercially made and untested and not certified then it's not going to get an ok from anyone but me. That's the rub I guess. It's an interesting problem though. I wish you well with your restoration. I love old houses and have lived in a few oldies but goodies over the years. The one you describe sounds like a real piece of history. Have fun with it. And anything you come up with I'm sure will be well thought out. Maybe someone will point us both in the right direction. I guess is ignorance is bliss because I was happy to just to pop off the plywood and go for it. The more I learn the more I worry about doing it. There seems to be a lot of opinions on this subject but I have yet to see anyone post a single definitive law or page from the fire/ building code to prove it one way or another. Thanks again.

The hard thing with fire and building code is there are so many regional differences. That, and a region or state will adopt a model code for their fire code (i.e. NFPA 5000, IBC, UBC, etc.) and then monkey with a few parts of it. The only way to know for sure what applies to you is to ask your local AHJ.

That being said, as far as I know for residential use, floor grates are not illegal, and since the worst kind of failure a floor grate protection system could experience is lack of operation leaving you with just a floor grate, I don't think a home brew system could be illegal. It could never be worse than just having an open grate.