Class A ?

I need to extend my chimney about 2 ft. My nice white chase top is getting the brown streaks on the sides.
The pipe is ICC Excel.
I called 2 places, one nearby has 2 12" discounted because they were "lightly used" from a store demo. Burned a half dozen times she figured. Priced at half off ($91 total), coild probably talk them down more. Otherwise the other store, new 24" is $144. Any reason not to use the 2 12"? Would it be any less sturdy? Another joint to cause an issue? Or is saving $50 worth it? Any input appreciated!!

 

Go for it
they lock together, right?
Save the dough!

 

No they slide together and screwed on 3 sides

 

I'm only 7" of pipe above it right now and then the cap. Draft is plenty good just want to get it up and away from the chase top to prevent some of the condensation/smoke stain drip off of it.

Here it is before house was finished obviously.

 

As long as it won't bug ya to see 2 feet of stainless sticking up in the air past your chimney go for it...

 

I'm thinkin my spring sweeping and fall pre burn check will be when I add or remove the extra section. I won't be outside at it in the winter other than to see if I'm burning clean. Which isn't going to be much of a problem with the IS.

I was hoping the height would be ok but with the reload smoke for 5-15 mins, 2X a day and then the condensation its going to need to go up to see if it helps. I noticed this morning with a slight breeze the smoke/steam actually blows downward breifly with gusts and slight wind changes.

 

I watched my neighbors chimney today and the wind and gust were swirling his smoke was going in every direction including up and down, it was pretty wild actually...

 

Grab it, Sconnie. I wouldn't worry about 2-12" pieces as opposed to 1-24" section.

Its on the outside of that shack anyway...

It does look like you are conformed to termination requirements already though.

Now about the streaks on your chase top....how long ago was your wood cut?

Maybe a dark color chase top is easier? Gonna keep dripping down though...

 

Wood (mostly red oak) was css for 3 summers. The bigger pieces I checked read 15-18% on fresh split back in the fall. So I should be good there. Maybe there is some towards ground level that aren't as dry? It all seems to light up fine without hesitation.

I also wonder if I'm just closing the cat too fast (600 on probe and within 5 minutes of reload) and some smoke is sneaking by and going up the chimney after its engaged until it catches up?

 

Yeah I think you are going to continue to get the same black drips no matter what...its pretty hard (with a modern stove) to waste enough heat up the flue to keep that cap hot. And if you think about it, even wood that is 15% MC still has a good bit of water in it...and it gonna make a lil steam, mix with the soot...make black water. Might hafta have a mini gutter system made for your chase

 

Don't really know if extended the height would help with the problem.
Could always try it out with just a piece of single wall pipe, no?

 

You will not get rid of the streaks by extending your class A. What you will do is reduce the exit temperature slightly but get more draft from the added height. You will also make that chimney harder to clean from the top down. I think I would try adjusting your typical stove top or pipe temperature instead. A little hotter should mean less condensation at every point in the flue system.

 

By increasing the height of the chimney, wouldn't that also increase the draft???

With the draft increased, wouldn't that also increase the stack temp???

With increased stack temps, the flue system would be a little hotter at every point in the system.....and less condensation

For $100 (or even less if you try the single wall pipe approach), it sure is worth a try.

 

I was looking at it the other way Dave. Any extension will be running exposed to outside air temperatures, not in the chase, so will likely cool off more before it reaches the top. You could be right though, I really don't know where the balance between draft and cold air will come out.

 

It sure will be colder outside of the chase. But the class A is insulated; that helps. And I have never seen a chase that was insulated but being enclosed like they are, that helps also.

I had something similar back in the 80's where I needed an OAK but thought it was a draft issue. ended up putting on a single wall pipe extension on top of a masonry chimney to see if the draft was the problem.....Ended up helping just a little but not solving the need for a OAK.

If I knew then what I know now.....

 

I actualy insulated my chase, for the small amount extra it cost, I figured it couldn't hurt. It is outside the house's envelope so not sure how much warmer it actually is in there? And really no way to insulate the top effectively other than just a piece of plywood with a hole 2.5" bigger than the pipe all the way around.

 

Thanks for all the input. I discussed it with my chimney installer and he also stated there is really no way around the condensation. He says its common even on a NG furnace exhaust you will see it, even icicles hanging from them.

I did add just 1 12" section to get it up from the chase top so it could breath a little easier, putting it at about 18" to the bottom of the cap. Hopefully the smoke/steam will not swirl around the top as much. He also recommend that incase snow were to pile up and get near the cap with it only 6-7" up.

 

I'll bet with the inside of the chase being insulated that as soon as the flue hits the outside, BAM! instant condensation. Probably not much heat loss from your class A through out the chase.

Let us know how the extension performs, please.