class A chimney

[weezer4117]

hey folks! i have a majestic prefab fp and chimney. i have ripped out the existing hearth and rebuilt one that will be up to code and stand the weight of my stove. i am going to use the existing chase to run double wall, insulated chimney pipe all the way up. there are two liners in the prefab chimney, (8" and 12") i will be removing the 8" obviously. now here is my problem, how am i going to support the weight of the new double wall pipe? i dont want to remove the 12" liner and i dont want to install a ss liner. the stove will not set inside the firebox AT ALL, it will be on the rebuilt hearth. should i block off at the top or bottom? i would prefer to block the bottom using sheet metal or insulation. i have tripple checked and i will have 6-8" clearence to combusibles all the way to the top of the chimney. the pipe i will be using is made by supervent, again the problem is supporting all the weight?!? maybe metal duct straps? any thoughts??? thanks, wes

 

[humpin iron]

yank both layers of the chimney, firestop the top of the firebox, use a roof support kit (wing style) and put a couple 4x4 across the framing to pick up the weight.

 

[snowtime]

humpin has got it right. The only question I have is how tall is your chimney? The roof support works good but does have a limitation on pipe below the brackets. Check the manufacturers specs on roof support kits. I installed 2 on mine and they work well. Of course you know the class A chimney will be a tough fit and cost more than a liner. Why not go for an insulated liner?

 

[weezer4117]

snowtime, believe it or not i can do a totall class a install cheaper than a ss liner w/ insulation. i can get double wall insulated pipe in 36" sections for $60. my chimney is only 15' tall. ill have $300 in pipe vs. $600+ in liner and insulation. the "wing" support will only have 10' under it AT MOST, most munufacturers say a wing support can hold 20' under and 20' on top, ill think thats a little steap myself. but i dont have to worry about that, i only have a total of about 15' for the whole thing!!(thank the good man above) WG

 

[DAKSY]

[quote author="weezer4117" date="1230340693"]snowtime, believe it or not i can do a totall class a install cheaper than a ss liner w/ insulation. i can get double wall insulated pipe in 36" sections for $60.

?!??! You sure about that? An APPROVED UL LISTED Class A chimney section sells for about $60 a FOOT around here...
Crikey! Single wall welded seam 22 gage connector is $10-$12 a foot...
I'm not doubting you, but somethin don't quite sound right, here...
What brand are you buying for THAT price?

my chimney is only 15' tall.

You might wanna check the minimum chimney height your stove is tested at...15' is not very tall & may have some SERIOUS drafting problems...

ill have $300 in pipe vs. $600+ in liner and insulation.

$600 sounds about right...Uninsulated liner kits are $425 for inserts & $480 for tee kits $200 +/- for the insulation...

the "wing" support will only have 10' under it AT MOST, most munufacturers say a wing support can hold 20' under and 20' on top, ill think thats a little steap myself. but i dont have to worry about that, i only have a total of about 15' for the whole thing!!(thank the good man above) <.

Once again, doesn't sound like it's gonna be tall enuff...but I've been wrong before...

 

[weezer4117]

daksy, the brand i am using is supervent. you are rite, i might make the chimney a little bit taller than 15', the existing chimney that is in my house drafted just fine w/ a wood fireplace but im not sure how it will do w/ a stove. i dont have the manual for it either, so i better be safe and add some chimney. the local menards has approved ul listed, class a, double wall insulated pipe for $60/3ft. i done alot of research on supervent, for the quality/price/durability i couldnt see a difference, only in price!! the reason i am using class a is because my existing chimney was a prefab, not listed for stove temps. so i removed it and have to replace it with approved material. WG

 

[snowtime]

Ok, if your going the Class A I would get 1 piece and lower it down the chimney to be sure it will go better yet make a mock up so if it gets stuck you won't mind beating it to get it out. Also before you buy be sure to figure out how to install it. I mean are you going to put one piece inthe fireplace and lift it each time you add. That would be tough as the chimney gets heavy quickly. Second if you lower it into chimney you have to make something to lower it with. You could make a tripod for the roof and use a pulley to lower the class A. Just some thoughts I know you can do it but there is lots to consider. I would put 1 extra 3' piece to make it 18' for draft. The liner + insulation will be a simpler install. Let us know how it goes.

 

[weezer4117]

snowtime,

i am not restrected to the roof and floor, i can also assemble in the attic (tons of room!) as a matter of fact the attic is where i was going to assemble most of the chimney. also i think i will use a "wing" bracket to secure the pipe to the roof/celing. the supervent pipe twist locks together so it will be perfect for these conditions. also i am going to replace some of the 12" existing pipe around the class a in the attic/roof area just for "extra" precautions. everything is falling into place thanks to all of the advice i am getting off of the forums, THANKS ALOT WG