Secondary Air for Trident SF160

I have read that secondary air is needed to prevent puff backs. In the cad drawing below is an idea I had to put preheated secondary air into the fire box. The small pipe I have drawn in the rear of the fire box which would run from the ash pan area to the top of the fire bricks is what I am proposing. There would be two pipes, one in each corner of the fire box. I would notch the corner fire bricks to go around the pipes. Would like opinions and suggestions from you hand fired pros if you think this is worth doing.

Your going to lose draft as you making a bypass from the ashpan to above the fire. How are you going to regulate the air flow? All the air has to come thru the fire from the bottom.

crazy4coal wrote:All the air has to come thru the fire from the bottom.

Not really, it's ok to have a little top air, it helps to control overshoot of the boiler water during no-load times. As it is now I keep the load door vents open about 1-1/2 turns out, but that has to be adjusted during reload time and some times I forget to go back and close them down once the new load of coal gets going. I'm thinking the pipes would be 1/4" or 3/8" black iron pipe.

crazy4coal wrote:Your going to lose draft as you making a bypass from the ashpan to above the fire. How are you going to regulate the air flow? All the air has to come thru the fire from the bottom.

Not always, my gibralter took air form below the grates for secondary air, it brought it in front of the coal banking bar. Now I am sure this was all figured in in the design.

JBSPARKS, look at the pics of my stove(towards the end of the posts) you will see the ds has a tube running sideways with holes and pulls the air from outside of the stove. These smaller holes allow much better air mixing for seondary burn. You could do this and not drill all the holes and add them later as you see fit. Would take some modifications, but might be worth a shot.

Good luck, Eric

Coalfire wrote:look at the pics of my stove(towards the end of the posts)

gotta link?

Hi what I recently did on my Vig11 is this: I drill two 1/2 holes in the lower part of the front doors. Placed adjustable traps. At first I was supposed to go the same way you explained but some on the forum made me more aware of it so I decided to make a simpler desing. Made it 2 weeks ago and still testing the results. After reloading, the blue flames seem to arrive sooner and the outdoor sulfur smell also seems to be gone. On thing is sure: burning these gasses as soon as possible is better than letting them go in the chimney. As I said on the testing now and don't like to talk about things that I'm not sure of. For the bypassing of the coal bed, it is not a so big problem in my case. The amount of air is not very big and I can close the traps when the stove is returned to the running Temp. You can adjust your primary air control wider to overcome that. I also tried to have the secondary air warmer (air coming fron the holes must pass between the plate retaining the anthracite and the doors) in placing St.St. plates inside the front doors to reflect the heat toward the inside of the stove but removed them after testing. I don't know if warmer air is so important? I always thought it was but no more sure of that. After loading the stove I tried to ajar the top loading door and it was making the blue flames arrive almost every time. The air entering from the top is cool air and ignites the gasses very easily. hope my long story helps.
Good luck , nortcan

Maybe this would be a better design?

Thanks Norcan, I'm thinking preheated air would work better. Let me know how your testing goes.

Axemans have a secondary air system, the fire viewing port. When the cumbustion fan is on the secondary draft is shut, and when the fan stops,the door opens allowing air over the fire. I assume the trident doesn't have a fan, I would think it would be better to take in secondary air from outside the boiler,not from under the fire. Do you have trouble with puffbacks ? A better thing may be to make a fresh air supply hose from outside the house to the area below the fire(or draft damper) to give more oxygen, is their a damper below the fire that opens up to control temperature?

Like the second design better...
I would take the air from outside of the ash area...
If you suck some ash the small holes will clog...
Better pressure differential from outside the stove too...
Looking to do the same thing with the DSM Basement #4 I have...

AA130fireman and Capecoaler, The reason I was thinking of taking the secondary air from the ash pan area was to get preheated secondary air in the fire box. You guys think it is better to get the air from outside the boiler? That would be an easier retrofit if that is the case. I have added a combustion blower to the Harman and on reload it is likely to back puff if I forget to bank the coals or open the load door vents a little more than I usually keep them.

Easier is better...
I think the iron pipe in the fire box will heat the air just fine...
I would add some way to regulate the secondary air...
thread the outside piece of pipe for a cap with different sized holes or some kind of flapper...

Thinking about this second design, what do you guys think would make a good high temp gasket to go around a 1/4" black iron pipe? I could run the pipes straight out the front of the fire box if outside the fire box air is better than preheated air.

CapeCoaler wrote:some kind of flapper...

I was thinking about a tear drop flapper like the ones on the Chubby.

Or screw in jets like a carb...
I like the flapper better less likely to clog...
Stove cement but messy...
Rutland has a black 1200* sillycone that might work if the temps are right...
Braze or wire weld for a permanent solution once the testing phase is over...
On second thought...
The 1200* sillycone would allow for testing and easy replacement if the pipe gets consumed...
Support both ends it gets warm in there...
Keep it 1" off the bricks so it does not get buried in ash or coal...

I think the same, try to take air from outside of the stove. It's easier to make and easier to control. On mine the air rising in front of the doors keeps the glasses cool and clean. When shaking I let the holes open. I thank Greg L because he made mr thought to make the traps adjustable. franco b also helps with this idea.
nortcan