BI METALLIC PRIMARY AIR CONTROL?!

 
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warminmn
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Post by warminmn » Fri. Dec. 14, 2018 6:52 pm

Lightning wrote:
Fri. Dec. 14, 2018 6:22 pm
I ended up just using the pipe caps. I cut a set of caps into a 3/4 pie, another set I drilled small holes, and then I also have solid caps to cut the secondary air completely. You could do something similar or fashion a swinging plate with spring resistance to hold it in place.
I came up with my designs from Lightnings posts so he/you gets the credit, but here is one of the 2 swinging gates with a spring and bolt I have on my stove, one on each side. The string you can see is a gasket I added this year. At first I had holes drilled on the inside part but ended out taking those out and just aimed both ends towards the bottom of the back of the stove. It isnt uncommon for the back outside of my stove to shoot up to 700-800 degrees burning off gasses with anthracite and dare I say higher with soft coal or wood on occasion. Theres a baffle over where those flames hit. The covers do leak a little but its likely the only leak I have so doesnt seem to matter.

There used to be 2 rows high of firebrick inside this stove so the pipes are higher than they probably should be now, but it works so i left it there after I removed a row.

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ratherbeflying
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Post by ratherbeflying » Fri. Dec. 14, 2018 8:30 pm

ok so i really love this whole idea, but the stove works on "vacuum" so i would imagine if i have too much secondary air it would pull easier from the secondary then it would from the primary which would loose the fire eventually i would think...? how do i know how much is too much?

 
franco b
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Post by franco b » Fri. Dec. 14, 2018 10:17 pm

ratherbeflying wrote:
Fri. Dec. 14, 2018 8:30 pm
how do i know how much is too much?
The purpose of secondary air is to burn the initial gas given off when a batch is first heated, and secondarily to burn off carbon monoxide gas formed under air restricted conditions; those short blue flames in a well established fire. I think experience and observation is the only guide. With continuing interest you will get a feel.

 
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Lightning
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Post by Lightning » Sat. Dec. 15, 2018 4:48 am

ratherbeflying wrote:
Fri. Dec. 14, 2018 8:30 pm
if i have too much secondary air it would pull easier from the secondary then it would from the primary which would loose the fire eventually i would think...?
For this to happen the secondary air would need to satisfy the vacuum inside the stove. This could be true if using a manual pipe damper because it restricts volume flow capability. But since a baro does not have this side effect, it takes a huge amount of secondary air for it to get to the point of effecting the primary air. For example, opening the load door wide would do it.

I've taken readings underneath the grate with the secondary air open and closed, the negative pressure did not change, unless I opened the load door.

Objectively speaking and in defense of the MPD, it would need to be at least partly closed which is something an experienced coal burner would not do in a low draft probability situation.


 
ratherbeflying
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Post by ratherbeflying » Sat. Dec. 15, 2018 1:33 pm

oh awesome, i dont even have a mpd, i am still debating if i should install one, i would think the baro and the secondary air would trump any effect the mpd would help with for the most part.... i may wait until i get a feel for the stove more with the baro and the secondary air installed and then later maybe install an mpd so its not too many variables at once to try to learn... but then again maybe i wont even need an mpd at all... but if it will also make the stove even more effecient then its something i would like to add eventually...

 
ratherbeflying
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Post by ratherbeflying » Mon. Dec. 17, 2018 11:00 am

hey lightening how many lbs of coal does the Clayton hold, i was thinking if its like my stove around 85lbs then your secondary air sizes should be similar to what mine should be...

 
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Lightning
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Post by Lightning » Mon. Dec. 17, 2018 3:40 pm

ratherbeflying wrote:
Mon. Dec. 17, 2018 11:00 am
hey lightening how many lbs of coal does the Clayton hold, i was thinking if its like my stove around 85lbs then your secondary air sizes should be similar to what mine should be...
Yes, I agree, I replied to your private message also :)

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