Questions about my build...

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Re: Questions about my build...

Postby rjdudley » Thu Jul 18, 2013 12:02 am

Excellent responses men! You guys never let me down.
So, the build continues tomorrow by adding the durarock on top of the bricks and attached to the wall standoffs.
I will implement both of your suggestions by using hardibacker, not durarock, for framing and then late when we fire it up keeping an eye on the hot spots. This means we won't be putting the rough sawn lumber on for a few weeks so we can do our testing, but, we're ok with that. Patience will pay off here.
One other question about the length of the exhaust tubes. I was going to go with the 30 ft. length for 8" pipe, but, if you look you'll see we have the burn chamber now on the right side in the photo. This means my length off pipe may now only be 16-18 feet. Too short?
My concern is that I need to put the external exhaust pipe venting out behind the barrel. If I include a 6ft vertical before exiting the wall I could now have 22-24 feet before going outside.
I suppose I could do some rather innovative permutations in the bench, but, do you think it's necessary?
Ray
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Re: Questions about my build...

Postby matt walker » Thu Jul 18, 2013 3:01 am

Ray, I used hardibacker as a catch all for cement board. Sorry about that, either Hardi or Durarock will be fine, whichever you prefer. I find the hardibacker easier to cut and handle, but Durarock does seem more robust to me. Anyway, your call.

As for length of flue in the mass, it's more about the size of your battery. The stove will run great with that shorter length of flue, actually it will probably be less finicky that way. If that's what fits in your space, and you feel like you have maximized your mass for your particular circumstance, then great. I would have liked to have longer benches on mine, but I was concerned with weight since my build is on a suspended floor. I started with a short bench and then once I was confident I wasn't stressing the floor I added another section. I found that I really wanted it to be long enough to lie down on, so I lengthened it so I could.
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Re: Questions about my build...

Postby rjdudley » Thu Jul 18, 2013 12:27 pm

Very intriguing answer. Since I'm likewise concerned about weight (even to the point that I've put extra lolli-columns in the under the floor) do you think hardibacker could replace the durarock? We know it can take the heat since it takes the intense heat of the burn chamber AND it's lighter than the durarock. Because I'd be more than happy use it on the next level, which is on top on the bricks and then attaching to the standoffs.
Do you think hardibacker and durarock have similar heat resistant properties?

If I'm ok with the shorter exhaust pipe length what types of temps going through the wall? I'm assuming we're no longer talking about approx. 100˚, right? I'm wondering if I need to use double wall pipe at the wall.
Ray
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Re: Questions about my build...

Postby matt walker » Thu Jul 18, 2013 4:35 pm

I think I'd probably stick with the Durarock for the underlayment. I trust that glass mesh to hold the sheets together and it is used in hearth builds commonly.

Your exhaust temps will surely be higher than that, mine are in the mid 200's after the whole thing is warm, so you can expect similar at the lowest, I would guess. If you already have a bunch of flue pipe I say run what you have until you get a feel for how it's working, if you have double wall, sure, that would be a great place for it. I doubt you'll need it, but you'll be able to evaluate that once you get there.
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Re: Questions about my build...

Postby rjdudley » Thu Jul 18, 2013 7:43 pm

I did just as you suggested and used the durarock. Here are the updated photos. Nothing earth shattering, but, an update nonetheless.
Image

Image

Image

Making progress! I have a friend that's bringing me a couple of yards of clay next week from a clay pit here in town.
I haven't built the heat riser yet because I was waiting until I moved the burn chamber, aka "The Beast", into the house. I just found out I don't have access to the 14" duct pipe I was going to use. So now I'll have to figure out what to use for the outside ring of the riser.

So, Matt, et al, you think I may be able to get away with single wall pipe exiting through the wall eh? Time will tell.
Ray
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Re: Questions about my build...

Postby matt walker » Fri Jul 19, 2013 4:30 pm

Looks fantastic Ray. If you are going straight through an existing wall and there isn't a thimble there already you will want to put one in, or some sort of protection, regardless of type of flue pipe.
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Re: Questions about my build...

Postby mannytheseacow » Sat Jul 20, 2013 12:35 pm

It's looking great, Ray! It won't be too long now and you'll have a new heater!

I would agree with Matt, even if you didn't need double wall, I'd use it just so I could sleep soundly at night without worrying my house might catch fire. Now's the time to do it right!
"Knowledge is power. Arm yourself."
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