Secondary Air Distribution System

Re: Secondary Air Distribution System

PostBy: Stanb999 On: Fri Nov 29, 2013 9:45 am

Lightning.. :dancing:

Great work! Keep it simple till you get things figured out. Simple cold rolled steel pipe could be installed later if the conduit craps out. I'd even go so far as to have it made if you don't have a machine shop. They could add threads to your stove wall and thread the pipe so it just slips in place for a good clean finish. Then you can add a simple spinner for adjustment of the air flow.

In your video the air really seems to be moving fast. Is this the case? Slowing the air down would get you more heat transfer.
Stanb999
 
Stove/Furnace Make: Harmon
Stove/Furnace Model: Mark II

Re: Secondary Air Distribution System

PostBy: Lightning On: Fri Nov 29, 2013 9:58 am

Thanks Paul :D

I'm seeing pretty even distribution of the air. Seems flames are spread out across the top of the coal bed evenly at different volumes of secondary air. I believe the pipe size relative to the distribution holes is the reason. A smaller pipe would loose pressure towards the back.

I like your idea of having different sized "caps" to regulate the secondary air volume :D The caps are cheap and easy to work with. I like the sliding tube inside the tube idea too, but I'm afraid the cutting of the pipe has burred up the end and I'm not sure if it will work out unless I disassemble the whole thing and clean up the ends, which I might do anyways lol
Lightning
 
Hand Fed Coal Furnace: Clayton 1537G
Coal Size/Type: Nut Size / White Ash

Re: Secondary Air Distribution System

PostBy: Lightning On: Fri Nov 29, 2013 10:18 am

Stanb999 wrote:Lightning.. :dancing:

Great work! Keep it simple till you get things figured out. Simple cold rolled steel pipe could be installed later if the conduit craps out. I'd even go so far as to have it made if you don't have a machine shop. They could add threads to your stove wall and thread the pipe so it just slips in place for a good clean finish. Then you can add a simple spinner for adjustment of the air flow.

In your video the air really seems to be moving fast. Is this the case? Slowing the air down would get you more heat transfer.


Thanks Stan!! I was thinking some black iron pipe custom length and threaded at my local Ace hardware store :D

The air movement in the video is caused by a -.04 of pressure in the fire box AND with the secondary inlets 100% open. After the video I covered them 50% at that point the flames seemed healthier and not so pushed around.

Thank you for watching the video and your advise :D
Lightning
 
Hand Fed Coal Furnace: Clayton 1537G
Coal Size/Type: Nut Size / White Ash

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Re: Secondary Air Distribution System

PostBy: Lightning On: Fri Nov 29, 2013 11:26 am

So far, the biggest advantage to the secondary pipes is duifing burn off of volatiles after fresh coal is added. I'm able to capture the heat instead of it going up the chimney. I get over 120 degrees in the warm air duct for the first hour if I adjust everything proper shortly after ignition.

After that I expect the heat gain will be slight but only if the secondary is set just right.
Lightning
 
Hand Fed Coal Furnace: Clayton 1537G
Coal Size/Type: Nut Size / White Ash

Re: Secondary Air Distribution System

PostBy: Sunny Boy On: Fri Nov 29, 2013 12:00 pm

I wonder if, at some point late in the burn cycle, the secondary's over-fire air will act like a check damper by lowering the stack temp and reducing draft ?

You could add another limiting factor by using several smaller holes in the end caps instead of one larger hole. The small holes would add another point of air flow limiting resistance as the fire tries to draw more air than you want it too. Much like turbo charger systems can naturally limit boost by simply reducing pipe sizes to the point where they become a natural restriction to maximum flow. With that built into the turbo and exhaust system, it doesn't require additional boost control devices, and it doesn't impact low flow performance.

You may be able to come up with cap hole sizes that make it a set and forget system.

Paul
Sunny Boy
 
Hand Fed Coal Boiler: Anthracite Industrial, domestic hot water heater
Baseburners & Antiques: Glenwood range 208, # 6 base heater, 2 Modern Oak 118.
Coal Size/Type: Nuts !
Other Heating: Oil &electric plenum furnace

Re: Secondary Air Distribution System

PostBy: Lightning On: Fri Nov 29, 2013 4:36 pm

I picked up some conduit caps and drilled holes in them. They pop on and off pretty simple. It's a step above the foil tape hahaha.
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Lightning
 
Hand Fed Coal Furnace: Clayton 1537G
Coal Size/Type: Nut Size / White Ash

Re: Secondary Air Distribution System

PostBy: Sunny Boy On: Fri Nov 29, 2013 5:03 pm

Nice job ! Much more professional looking ! Ya might wanna de-burr those holes. Not so much for better air flow but for less blood flow ! :D

But, the duct tape look had it's charm too ! :D

Paul
Sunny Boy
 
Hand Fed Coal Boiler: Anthracite Industrial, domestic hot water heater
Baseburners & Antiques: Glenwood range 208, # 6 base heater, 2 Modern Oak 118.
Coal Size/Type: Nuts !
Other Heating: Oil &electric plenum furnace

Re: Secondary Air Distribution System

PostBy: Lightning On: Fri Nov 29, 2013 5:35 pm

Yes a deburring is in order lol. I bought three sets of them so I can have them set at different volumes :D
Lightning
 
Hand Fed Coal Furnace: Clayton 1537G
Coal Size/Type: Nut Size / White Ash

Re: Secondary Air Distribution System

PostBy: nortcan On: Fri Nov 29, 2013 8:42 pm

Just an idea:
do you think that having a much larger pipe, or Ex. a 2"H X 1/2"l channel or any larger size to have a sort of air warmer chamber with a larger volume of heated air and having drilled holes on the side of it could be an easy way to ""pre-heat the air in the tube ?
Larger volume of air with small openings to keep the air a longer time Inside of the chamber???
Hope the French can be understand :oops:
nortcan
 
Stove/Furnace Make: Stuart,Peterson/ Grander
Stove/Furnace Model: Sunnyside/ Golden Bride

Re: Secondary Air Distribution System

PostBy: Lightning On: Fri Nov 29, 2013 10:32 pm

nortcan wrote:Just an idea:
do you think that having a much larger pipe, or Ex. a 2"H X 1/2"l channel or any larger size to have a sort of air warmer chamber with a larger volume of heated air and having drilled holes on the side of it could be an easy way to ""pre-heat the air in the tube ?
Larger volume of air with small openings to keep the air a longer time Inside of the chamber???
Hope the French can be understand :oops:


I think I understand partner :D
Yeah, a bigger tube or a rectangular tube should preheat the air more. I'm not clear on why that's absolutely necessary. When I look down the tubes I can see the air dancing against the cap at the other end so I bet it's hot in the tubes :D
Lightning
 
Hand Fed Coal Furnace: Clayton 1537G
Coal Size/Type: Nut Size / White Ash

Re: Secondary Air Distribution System

PostBy: dlj On: Sat Nov 30, 2013 11:01 pm

Love your drilled caps!

Now, how about if you drill bigger holes in them, run a screw through the middle of the cap from the inside out, drill and tap a hole in a flat piece of metal so you can screw it on and off and you have a variable air feed... Oh right, that was the spinner idea posted much earlier in this thread... But now you have the first step done! ;)

dj
dlj
 
Hand Fed Coal Stove: Vermont Castings Resolute
Baseburners & Antiques: Glenwood Baseheater #6
Coal Size/Type: Stove coal
Other Heating: Oil Furnace, electric space heaters

Re: Secondary Air Distribution System

PostBy: Lightning On: Tue Dec 03, 2013 7:17 pm

I modified my caps to get different volumes thru the secondary pipes. Today I had the V shaped ones in. When I came home I had 263 degrees over the load door and 164 on the pipe. Thirty minutes after replacing those with the small holed caps, I had 268 over the load door and 158 on the pipe.

I'll be straight up and honest as I can, I can't justify the heat gain in my warm air ducts with a mature fire (12 hours since shake and load), even though the over the load door temp increased and the pipe temp decreased. If there is heat gain, its only a degree or two at most and I can't verify it since the cold air return could be fluctuating that much. :? :lol:

BUT, it does have its advantages. I get a nice capture of heat during burn off of volatiles where I didn't before. I'm also seeing a nice even burn of the coal bed since secondary air isn't just spilling onto a portion of the coal bed. The coal bed looks much healthier and I'm noticing the red glow on top is wider, since I suspect that secondary air is oozing down the sides of the fire brick too and reacting with the sides of the coal bed.

That's all I got so far 8-)
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Lightning
 
Hand Fed Coal Furnace: Clayton 1537G
Coal Size/Type: Nut Size / White Ash

Re: Secondary Air Distribution System

PostBy: Sunny Boy On: Tue Dec 03, 2013 8:09 pm

Interesting. The secondary pipes have increased the stove temp, and dropped the pipe temp. Adding the smaller hole caps is making the stove even hotter and the pipe cooler. But no as-big increase in duct temps, . . meaning that increase in heat, if it's not going up the pipe, where is it going ????

How do those numbers compare to there being no cover at all on the pipes ? Might show a trend toward what would be the best hole sizes.

The beds burning more uniform ,are you seeing a difference in the ash ?

Paul
Sunny Boy
 
Hand Fed Coal Boiler: Anthracite Industrial, domestic hot water heater
Baseburners & Antiques: Glenwood range 208, # 6 base heater, 2 Modern Oak 118.
Coal Size/Type: Nuts !
Other Heating: Oil &electric plenum furnace

Re: Secondary Air Distribution System

PostBy: Lightning On: Tue Dec 03, 2013 11:51 pm

Sunny Boy wrote:Interesting. The secondary pipes have increased the stove temp, and dropped the pipe temp. Adding the smaller hole caps is making the stove even hotter and the pipe cooler. But no as-big increase in duct temps, . . meaning that increase in heat, if it's not going up the pipe, where is it going ????
The subtle change in temp on the furnace isn't enough for me to measure in the warm air ducts. A 5 degree increase on the furnace would only amount to a fragment in the warm air ducts. I usually see 118-120 degrees in the duct when I have 370-380 on the furnace. SO it takes a 100 degree increase on the furnace to see an 18-20 degree increase in the warm air ducts. I kind of expected this. I didn't think I would see a huge increase in heat output, although I was hoping for a small measurable amount. I've always thought that anthracite burned pretty efficiently without secondary air after volatile burn off. I'm willing to say there is less than a few % CO as compared to CO2 in a mature slow burning coal fire. The only extra heat I'm gonna get is by converting that CO into CO2 with secondary air. Maybe I'm wrong here. I dunno lol.. I'm sure I get a little more heat with the 5 degree increase on the furnace but Its hard to prove it :lol:

Sunny Boy wrote:How do those numbers compare to there being no cover at all on the pipes ? Might show a trend toward what would be the best hole sizes.
With no cover on the pipes, the pipe temp runs higher and the furnace temp falls. UNLESS its after a fresh load of coal.

Sunny Boy wrote:The beds burning more uniform ,are you seeing a difference in the ash ?
I don't think so.. Ash seems the same.
Lightning
 
Hand Fed Coal Furnace: Clayton 1537G
Coal Size/Type: Nut Size / White Ash

Re: Secondary Air Distribution System

PostBy: oliver power On: Mon Jan 06, 2014 9:34 am

Lightning wrote:
Sunny Boy wrote:Is that one inch conduit ? If so, 3/4 inch fits rather nicely inside it. You could make them into rotary sleeve valves by having 3/4 conduit inside the 1 inch.

Drill matching holes from the 1 inch into the 3/4 inch. With the 1 inch tubes fastened in place so they don't move, when the 3/4 inch tubes are turned they will start to close off the 1/4 inch holes because of the holes going out of alignment. That will restrict all the holes in the pipes equal amount at the same time. ;)

Edit, ok, I see your using 1-1/4 inch. How snug does the 1 inch fit inside it ?

Paul


Awesome idea, some of my holes aren't in a perfect line due to the drill dancing around. But I understand your suggestion, its excellent since it would restrict each hole individually. But lining them up would be challenging :D
Maybe already mentioned by now. Slide one pipe into the other. Then a shot of spray paint though holes. That should mark the holes to be drilled through inner tube.
oliver power
 
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