6" to 8" Conversion at the seacow

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Re: 6" to 8" Conversion at the seacow

Postby mannytheseacow » Thu Sep 04, 2014 1:46 am

Oh dang it! Yes there's a spot at the end of the flue run, between the last clean out and the bypass section, that I could probably squeeze a damper in. It will still be some work but I think it's feasible. I really like the idea of closing that mass off in the dead of winter to store that heat. Better to install it now than tear it apart later and do it right. The hardware store doesn't have any in stock right now though and I can't complete anything else on this build until I tear in there to put the damper in.
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Re: 6" to 8" Conversion at the seacow

Postby matt walker » Thu Sep 04, 2014 2:37 am

Ha! Sorry man.
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Re: 6" to 8" Conversion at the seacow

Postby mannytheseacow » Fri Sep 05, 2014 11:17 am

Well I found an 8" damper off of an old stove and tried to get it in place just under the bypass section. I spent about 2 hours fiddling with it and it just won't work there. Oh well. I ended up re-installing it just above the bypass section at the final exhaust before it enters the chimney. I'm not sure how often it will be able to be used there, but there it is. Supposed to get down to 49* this weekend so I'm hoping to send her on a maiden voyage sometime in the next couple days. Keep your fingers crossed!
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Re: 6" to 8" Conversion at the seacow

Postby matt walker » Fri Sep 05, 2014 3:36 pm

Fingers crossed.

Hey, I just cleaned out my flue runs a week or two ago, and had so much less stuff than I had last year, due to better fuel I'm sure. How did your 6" flue runs look when you pulled them, with regards to build up?
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Re: 6" to 8" Conversion at the seacow

Postby ByronC » Fri Sep 05, 2014 9:25 pm

I was just wondering how the HVAC galvanized steel flues are holding up over time. Matt, did you notice any discoloration or tendency of deterioration beginning anywhere in your system? Curious to hear what Manny reports also.

I'll be starting my RMH (8" system) build around the first of October and have begun sourcing materials.
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Re: 6" to 8" Conversion at the seacow

Postby mannytheseacow » Fri Sep 05, 2014 9:50 pm

That's a great question, Matt. I actually meant to post about this and it got lost in the turmoil of the rebuild. In the flue runs there was a negligible amount of black grit- a gram or two at best. There was maybe an amount equal to the entirety of the runs deposited in the first clean out exiting the barrel. The largest amount, by far, was found stuck to the inside of the barrel, maybe 1/8 to 1/4 cup. Simply amazing. I would probably attribute these findings to the extreme cold winter as I imagine that the gasses were moving very quickly through the run and making most of their deposits in the verticals chimney flue (remember the several times over the winter my chimney became plugged).

Byron, tearing apart my flue runs I didn't really see any deterioration of the HVAC ducts. They were a little rusty on the bottom side where they had been sitting in the wet mass for so long before drying, though there was no pitting that compromised the structure of the pipe. Even if it did, I wouldn't worry as the cob is a well sealed mass by that time. FYI- I had 26 ga. duct in the 6" stove. My new build is a combination of 26 ga and 30 ga. Keeping my hopes up that I never tear this one apart to see if there is a difference!
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Re: 6" to 8" Conversion at the seacow

Postby matt walker » Fri Sep 05, 2014 10:45 pm

Right on Manny, thanks for that. Pretty incredible systems.

Byron, I haven't noticed any deterioration, although I'm not really giving them a thorough inspection. Just vacuuming and giving a cursory glance and kinda poking around with my arm. Like Manny, I don't think it's of any concern at all. The flue pipes offer no seal as it is, so it really doesn't matter if they are whole or not. The cob is doing all the work, the flue pipes are just mold pieces to form the cob around, in my opinion.
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Re: 6" to 8" Conversion at the seacow

Postby ByronC » Sat Sep 06, 2014 12:06 am

That's good news guys. Matt, I figured your RMH would show wear-n-tear the soonest if there were any, burning 10 to 11 cords of wood per heating season three years in the running, if I read that right. Man, that's a lot of wood, so your stove makes for an excellent "materials" test subject for the rest of us new RMH builders. With my high efficiency box stove consuming between 1.5 ~ 2 cords per heating season, my RMH should equal if not beat that, and obviously won't see anywhere near the use your stove is getting.

I'm probably just going to go the cobcrete route using $8 per 50 lb. bag fire-clay mixed with masons sand to encase the ducting and establish the primary gas seal, then add rock set in place with more cobcrete for the balance of the bench fill. Going to take photos and start a thread once the project is underway so you guys can tell me what I'm not doing right:->
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Re: 6" to 8" Conversion at the seacow

Postby ByronC » Sat Sep 06, 2014 6:56 am

Ooops, I meant 5 cords, not 10~11. It's another fellow that goes through 10~11 cords per winter... in Alaska!
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Re: 6" to 8" Conversion at the seacow

Postby mannytheseacow » Sat Sep 06, 2014 7:03 pm

I fired it up this morning. Sorry no pictures right now because I'm out of bandwidth.
I left 2 candles burning in it over night- one in the wall thimble and one at the far end of the bench. I put aside 3# of wood and got her going first thing this morning. Inside temp was 69*, outside temp 54*. Hot water tank was at 94* and the coil was sitting at 68* at start up.

First of all, what a behemoth! The feed on these 8" stoves is huge! I'm definitely going to burn more wood this year because I can fit like twice as much in at a time. First question- with these bigger stoves can you burn bigger chunks of wood or does it tend to creep out the feed?

Ok, anyway... Fired it up! After 15 minutes the barrel was running at 750*, and the coil was pumping 134* water. I just ran a single batch of wood through it to burn the form away and see how it worked. It quickly heated up my chilly house, but it is back in the 70's today so I didn't really want to heat the mass up much. I let the fire go out and after a while checked the water tank again and it was at 114* (before the solar panels had kicked in).

Here's a couple of thoughts: 1. Sweet! Well worth the effort of rebuilding. 2. The bypass is awesome. There wasn't a hint of smoke back even with a cold wet mass. 3. The coil seems work well despite the small size. 4. It was very interesting to me to play with the damper on the coil. First, by closing the damper on the bypass the coil temperature jumped almost 10 degrees. Second, as the plywood around the feed was burning away the stove started pumping. I opened the coil damper and it just started drawing that smoke down like crazy. 4. The color of the core is very dark, I'm pretty sure from the addition of the fire mortar added to the mix. I didn't think I added that much but the color seems to give the appearance that I did.

Anyway, I'll put some pictures up when my computer connects to the internet again. It's all done except for the top plaster coat but I want to let the mass dry out much more before plastering. Time to clean up the living room.
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