tearing roxul up and using it to insulate the entire length of the flue?

[Snotrocket]

For those of you against it what do you think the insulation that comes with an insulated liner is made out of? It's a very similar product.

An insulated liner will add almost $200 to the cost of your liner. A bale of Roxul is $40 at Lowes.....

 

[begreen]

I thought liner insulation was kaowool, but could be mistaken. Kaowool's melting point is listed as 3200 (1760). This is ceramic fiber as opposed to mineral fiber (Roxul). It's advantages are a high melting point, ease of use, low thermal conductivity and it's exceptionally non-reactive.

 

[oconnor]

For those of you against it what do you think the insulation that comes with an insulated liner is made out of? It's a very similar product.

An insulated liner will add almost $200 to the cost of your liner. A bale of Roxul is $40 at Lowes.....

If you want it done to code and manufacturers specs you use the stuff they recommend. Of you want to experiment, use whatever you want. Just remember that you are experimenting.

 

[begreen]

FWIW a big bag of perlite is about $32 at a greenhouse supply store, perhaps less at a masonry supply. It softens around 1600, but does not melt until 2300°F. Vermiculite will not melt until 2426. Home Depot sells vermiculite for about $21 for a 2 cu ft bag. You can get a better deal at on a larger bag at a large greenhouse or nursery supplier.

 

[Snotrocket]

I thought liner insulation was kaowool, but could be mistaken. It's melting point is listed as 3200 (1760). This is ceramic fiber as opposed to mineral fiber (Roxul). It's advantages are a high melting point, ease of use, low thermal conductivity and it's exceptionally non-reactive.

2000f or 3200f it doesn't matter. Your house is toast if it ends up reaching those temps. Your flu liner will be the least of your problems.

 

[Snotrocket]

If you want it done to code and manufacturers specs you use the stuff they recommend. Of you want to experiment, use whatever you want. Just remember that you are experimenting.

Almost every single installation I see on this board it is recommended that you stuff roxul behind your block off plate would you agree?

That is the hottest place in your entire flu run. What difference does it make if you use it the entire way up? Nothing. It doesn't make a bit of a difference.

What would you consider the exact to code way to insulate a flu? From start to finish, I want to hear it. Use your own towns code if you want.

 

[oconnor]

Almost every single installation I see on this board it is recommended that you stuff roxul behind your block off plate would you agree?

That is the hottest place in your entire flu run. What difference does it make if you use it the entire way up? Nothing. It doesn't make a bit of a difference.

What would you consider the exact to code way to insulate a flu? From start to finish, I want to hear it. Use your own towns code if you want.

I'm not here for an argument, but to answer your questions :

A block off plate is what is recommended. Some, including me, used Roxul as the method to seal the space. I wouldn't use Roxul above the plate if you made one from tin. No need. The insulation effect is not needed. When I used Roxul I was happy as I can remove all of it easily if there is a problem. There hasn't been.

As for the absolute correct way to insulate a stainless liner- follow the manufacturers instruction manual. Building code doesn't cover manufactured chimneys and liners except to say they must be used as instructed. If the manual doesn't cover insulation, then you can't do it. It's as simple as reading the instructions.

Problem is most folks never get instructions with the product they are using. Some liners that can be purchased haven't even been thru proper testing.

It's your house so do as you see fit.

 

[Snotrocket]

I'm not here for an argument, but to answer your questions :

A block off plate is what is recommended. Some, including me, used Roxul as the method to seal the space. I wouldn't use Roxul above the plate if you made one from tin. No need. The insulation effect is not needed. When I used Roxul I was happy as I can remove all of it easily if there is a problem. There hasn't been.

So you used Roxul in the hottest part of your entire flu run but you wouldn't use it the rest of the way. That doesn't make any sense at all.

I'm not here to argue either, but this is a discussion about using Roxul to insulate a chimney liner and whether it's safe or not, not point at the manual.

 

[oconnor]

So you used Roxul in the hottest part of your entire flu run but you wouldn't use it the rest of the way. That doesn't make any sense at all.

I'm not here to argue either, but this is a discussion about using Roxul to insulate a chimney liner and whether it's safe or not, not point at the manual.

You asked what difference it makes, so I told you that it isn't to code. The OP asked for thoughts, and they have been passed on.

You asked for specifics on exactly how to insulate a liner to code, and I explained that the manual covers it. I point you to the manual because they can all be different.

Sorry if you don't like what I have said. I can understand your defence of using Roxul in the entire chimney as it is how you have done yours. I don't think you are in danger, nor do I think the others who have similar reservations to insulating the entire liner with Roxul believe you are.

I just wouldn't do it. Testing and instructions are done for good reasons, and I'm not going to recommend against what they say.

 

[Snotrocket]

Sorry if you don't like what I have said. I can understand your defence of using Roxul in the entire chimney as it is how you have done yours. I don't think you are in danger, nor do I think the others who have similar reservations to insulating the entire liner with Roxul believe you are.

I just wouldn't do it. Testing and instructions are done for good reasons, and I'm not going to recommend against what they say.

I did use it and would use it again. So didn't you. You just stopped using it before I did. There is no difference between my install in yours. We both have Roxul stuffed into the hottest part of the flu run.

I'm recommending he do it. You're not.

See the difference yet?

 

[HotCoals]

I did use it and would use it again. So didn't you. You just stopped using it before I did. There is no difference between my install in yours. We both have Roxul stuffed into the hottest part of the flu run.

I'm recommending he do it. You're not.

See the difference yet?

He answered specific questions, He is not going to recommend or endorse something that he feels is not what the manufacture of a liner suggest.
There can be liabilities to that.
Most will read between the lines like I did.

 

[Snotrocket]

I'll consult my attorney the next time I make a post I guess. I wouldn't want any liability issues.

Both of you should get into politics.

 

[KindredSpiritzz]

I just dont see what a little bit of insulation is going to do in a chimney with such a narrow opening if its already almost touching the liner on 2 sides. That pipe is going to heat up that small air space making insulation irrelevant. I could see it being beneficial in a big chimney with lots of space around the liner but i dont buy into it for a small flue chase. Waste of time and pointless as far as im concerned. Maybe a block off plate on the top of the chimney to keep that heat in is all i'd do if you dont have one already.

 

[branchburner]

FWIW a big bag of perlite is about $32 at a greenhouse supply store, perhaps less at a masonry supply.

I paid much less than that for a pretty good sized bag (4 cu ft?) at the local masonry supply. Masonry perlite can be had at about $3/cu ft, if I'm not mistaken. (Wholesale price for masons seems to be a LOT less than retail price for gardeners.)

 

[Enzo's Dad]

I just dont see what a little bit of insulation is going to do in a chimney with such a narrow opening if its already almost touching the liner on 2 sides. That pipe is going to heat up that small air space making insulation irrelevant. I could see it being beneficial in a big chimney with lots of space around the liner but i dont buy into it for a small flue chase. Waste of time and pointless as far as im concerned. Maybe a block off plate on the top of the chimney to keep that heat in is all i'd do if you dont have one already.

I was been wondering about this same idea. My flue's inside diameter was 6.5 inches wide. I went with a 5.5 inch smooth wall(2ply) liner. I have a block off plate with roxul above the stove and roxul stuffed around the top of the liner covered with flue tile cover. ..I dont seem to have a draft issue, and honestly how long would it take to heat that space? When I talked to instalers before I put in a liner myself they all asked why I wanted to insulate the liner, they told me it was not needed.

 

[branchburner]

this is a discussion about using Roxul to insulate a chimney liner and whether it's safe or not, not point at the manual.

When insurance companies don't want to pay claims, or manufacturers don't want to honor warranties, or inspectors don't want to approve installations, they point to the manual. Even if the deviation from code or from the list of approved applications has NOTHING to do with appliance performance or with what might go (or has gone) wrong, there is no assurance that any such deviation won't be considered when addressing the claim or code compliance.

There are millions of safe ways to do things that don't meet with the approval of bureaucrats and lawyers. None of us -- other than bureaucrats and lawyers -- like living in a world of bureaucrats and lawyers, but we do. If we answer "yes" when someone asks "can I do this?" it is always worth qualifying our answer with respect to codes and warranties. How is that extra information harmful when added to a thread?

If you want to unilaterally decide that the appropriate content of threads should be limited to the aspects you yourself deem important, apply for a moderator job. Good luck.

 

[DougA]

If your flu temps are regularly 1200F you're doing something seriously, seriously wrong. Like burning gasoline in your stove.
The roxul will be more than fine insulating your liner.

Actually, that is not true at all. I would have agreed with you 100%, even bet money on it until I installed a digital probe into the flue. I was absolutely SHOCKED at how my wood burning has changed due to the probe. Typically, starting a fire, letting it go until a cast iron stove top thermometer reads 450+ before closing it down will easily give you flue temps of 1400+! That was what I did for 28 years. I suspect it would even be a lot higher but I'm afraid to test it.

After I put in the probe, my alarm goes off at 900 and that's when I close it down. Usually the stove top temps will only be 250-300 at that point. If I am in the other room when the alarm goes off and it takes me 30 sec to get there, the digital probe will be reading well over 1100 in that short a time. These temps are not what you get when running the stove normally, just at the start-up. If it's over the safe limit, it's over.

I would not recommend Roxul even though that's what I did years ago in a few small sections. I've got vermiculite in other areas. In my new install next year, neither will be there. I did get hold of roll of foil wrapped insulation that is used on restaurant vents to reduce clearance to combustibles, same as wood stoves. The product is insanely expensive. I recall $500. for a 2x10' roll but I got what was left over for free. Before someone posts on how restaurant vents are so much lower temps than wood stoves, do your homework on code. I bought a restaurant years ago and the entire vent system had to be replaced because it was not to code. Someone had 'paid off' the original inspector and I got sc***ed when it got inspected after I bought it.
The reason you do things to code is for your family's safety and so that your insurance is still valid if you have a fire.

 

[tcassavaugh]

I also decided to stuff roxul down from the top. Used a piece of wood to pack it in. I am definitely noticing a difference in heat output, and keeping the stove warmer, longer. Or maybe it's all in my head...

.........perception is reality.

 

[Brian26]

I also decided to stuff roxul down from the top. Used a piece of wood to pack it in. I am definitely noticing a difference in heat output, and keeping the stove warmer, longer. Or maybe it's all in my head...

Same here. My insert has been burning noticeably different. In a good way.

I am aware its not up to code or the proper way to do it but it works. Regular cleanings and inspections are a good piece of mind. I had practically nothing in my liner. Quick sweep and I was done.

 

[elmoleaf]

Two points to add:
1. Many misunderstand "code" to be a gold standard of sorts, or the best way to do something. Building codes are actually MINIMUM STANDARDS.
2. Perlite does indeed soften/melt at around 1700 F. I used some mixed with furnace cement for refractory in a homemade metal melting furnace. When I was messing around, I was tossing in dry wood chips with a blower on for fuel. I had a piece of steel inside the furnace and got it up to over a white heat, at which point I was damaging/burning the steel. The thermocouple in the furnace wall read somewhere around 1600-1700F. The furnace lid refractory was exposed to the most intense heat, and once removed, I found much of it had slumped and melted way. A lot of the remaining perlite had congealed into glassy clumps.

 

[branchburner]

Perlite does indeed soften/melt at around 1700 F.

Soften/sinter yes, but melt no, as begreen pointed out above. Melting is well above 2000F.

I believe to achieve its expanded/exfoliated state it is heated to even higher temps, but only for a short time, until it pops (much as quickly heating popcorn makes it pop, but it does not burn it unless exposed to that high heat for a certain sustained period of time).

 

[tjcole50]

I had plans to stuff roxul all around my liner at the block off plate? Is this not a good idea? No time to read all posts will go through?

 

[PLAYS WITH FIRE]

I made a block off plate out of Roxul as well as stuffed it up the smoke chamber....this will be the second season with the block off of Roxul and it looks just as it did when I first put it there. Take that with a grain of salt.....

 

[tjcole50]

Well seems a lot have it sitting directly on the liner at block plate I bought comfort batts and plan to stuff some at top of chimney too

 

[PLAYS WITH FIRE]

I did it...I'd do it again...matter of fact I just gave a friend a whole batt today to use as a block off till we both do the real deal( insert, buck 91, outside chimney). He said he don't get that much heat from it and he described the setup. I wish I'd a spoke to him sooner.