Greetings & A Question

[hicksonj]

Greetings,

Happy Sunday everyone. I am a first time poster from Hampden, MA. About 2 years ago, I purchased a 2000 sq ft farmhouse that depended on a glenwood "C" for heat. The stove was overheated badly/consistently and the last owned burned a bunch of trash. I found glass, milk cartons, magazines, plastic, and so much more crap 1/2 burned in the fire box and ash pan. The stove was about 6" from a wall-papered plaster wall and that was baked too. To boot, he had some raging chimney fires over the years. So... out with the glenwood, in with lp forced air, and a new wood stove. A chimney sweep and an expensive bill later, I had the chimney cleaned up, repaired, and the thimble replaced.

The chimney sweep only installed a 6" ID thimble. It is very heavy gauge galvi-steel, but it isn't exactly 6". It was pushed out of shape, loosing/gaining a 1/8" or so on the vertical/horizontal diameters. The thimble has good clearance to the studs and has a cement collar around it, coming to the surface of the my fire-rated cement board backer. Slate tile is laid over the backer, forming a little less than an inch of backing. I would like to use 6" double wall pipe to reduce my clearances, and there the problem presents itself. The thimble is 6" ID and the double wall pipe is 6" ID. I won't be able to fish the pipe through the thimble (which is 16" in length). So... without removing the thimble, does anybody have any ideas on how I can achieve a safe connection without busting in a new 8" thimble?

Thanks for the help!

~Joe

 

[fraxinus]

I'm not sure I understand the question. Why are you "fishing pipe through the thimble"? Thimble generally means the connection to the chimney to which the stove pipe attaches. If this latter is the case, then the 6" diameter is not a problem. A short piece of double male ended pipe - crimped at both ends - goes into the thimble. The stove pipe attaches to the other end giving you the correct connection of male ends going toward the stove. The crimping takes care of any diameter issues.

 

[hicksonj]

Ok... I was thinking that, but I'm not assuming anything in 50K btus

Shouldn't I crimp the thimble and insert it into the inner pipe? This would prevent the wet creosote from leaking outside the pipe.

 

[hicksonj]

Another quick question:

I cannot find any info of the R-Value of a cement hearth. I have a 1.5" cement hearth pad covered with marble tiles that are butted up right next to each other. My manual calls for a "R" factor of 1.0, and I'm just wondering if what I've got is sufficient? The outside dims of the hearth are more than enough to meet the requirements, but what about it's makeup?

Thanks again,

~Joe

 

[webbie]

Assuming 2 inches of solid masonry, that would not be R 1.
not nearly.
Depending on the exact composition of the cement, it is probably about R=.3, maybe less.

What stove are you looking at? Does it have an extra bottom heat shield available?

I think most double wall pipe brands have adapters available for either end - to transition back to single wall and therefore be able to continue right though your wall thimble.....did he use a UL approved wall thimble or something he made up?

 

[hicksonj]

I'm buying a Hearthstone Phoenix, so there is no bottom shield. I can (with an amount of work) pull up the freshly laid marble and put a layer 1" layer of Micore 300 on top of the cement.

Thanks for the comments on the double wall, better safe then baked.

~Joe

 

[stoveguy2esw]

Another quick question:

I cannot find any info of the R-Value of a cement hearth. I have a 1.5" cement hearth pad covered with marble tiles that are butted up right next to each other. My manual calls for a "R" factor of 1.0, and I'm just wondering if what I've got is sufficient? The outside dims of the hearth are more than enough to meet the requirements, but what about it's makeup?

Thanks again,

~Joe

here is a link to the applicable code (nfpa-211) its free to read but you cannot download or print free , its handy enough that i keep a link saved in favorites in my work and home computers , i also bit the bullet and bought the hard copy, read it and get a feel for what you have versus what the code requires, PM me if you have questions and i will try to get them answered for you as quickly as i can, here's the link (broken link removed to http://www.nfpa.org/aboutthecodes/AboutTheCodes.asp?DocNum=211&cookie;_test=1)

 

[fraxinus]

I think we've still got some confusion over the meaning of thimble. The thimble is the metal part the mason mortared into the chimney opening. One crimped end of the stove pipe or adapter goes into the thimble. The other crimped end goes into the pipe leading back to the stove. Any creosote then runs back into the stove rather than dripping out around the joints.

 

[hicksonj]

Ok... I've figure out the thimble issue. Thanks for all of you help.

Now... back to the floor for a second. I am so completely confused by the Phoenix manual, EPA regs, and the dearth of information of this site. I missed an "or" in my phoenix manual that states:

"An acceptable floor protector is a 3/8" (10 mm) minimum thickness non-combustible or listed floor protector with an "R" factor of 1.0."

I have 1+" of concrete and marble tile on top. This hearth is going to be a heat sink, but still complies with the 3/8" requirement. Can my current setup safely work??? I've spent 2 days reading and re-reading the EPA doc above and my manual, and I've basically permuted every possible hearth makeup possible with materials around my area.

I'm going to meet with my inspector tomorrow, but I want to be sure I'm 1/2 informed at the meeting.

FYI... if you are in western mass, Kelly Fradet Lumber can get Micore 300 for 44$ a 4'x8' sheet. I also know some good granite people in the area that can cut you a hearth to size for much less than the usual 35$ a square.

Thanks in advance,

Joe

 

[begreen]

So far the hearth as described is a heat conductor, not a shield. It needs an insulation barrier like micore to provide a thermal break from the combustible surface below the stove.