aof/auf

[asknupp]

Can someone please direct me with advice or pics on how to direct and tame down a high pressure blower for both auf and aof. I've seen where people have used baffles or valves to limit air. And I understand that to tame a hpb it must be on the intake side of blower but will worry about that after baffles are in place. I'm a visualist so pics are preferred.lol

[nymapleguy607]

on my arch I bring the air from the blower into a plenum, then I have dampers and control cables on the output side of the plenum. If the AOF and AUF holes are sized right balancing shouldn't be too much of an issue. I originally made the AOF nozzles 1/2" and the AUF nozzles 3/4". Once the system is fully pressurized there is backpressure from the AOF and it will overwhelm the AUF damper and allows too much AUF. I am changing the 3/4" holes to 1/2" for the coming year. Good luck

[asknupp]

My auf is going to be straight into the ash box and up through the grates. And aof is 3/8" nozzles into the back of firebox below the ramp.10162

That's why i feel I'll need some kind of baffles to control which gets more or less air.

[mellondome]

What size pipe from your blower.? You can get cheap "blast gates" that will fit round pipe from wood working sites. Put one going to each air destination. Then you will have complete control of the flow without restricting it at the intake.

[maple flats]

I don't have pictures ready, but on my AUF AOF HP blower, I did not restrict the intake. My blower is likely 100+ yrs old and I have no specs. However, it has a 4" intake and a 4" outlet. That sets outside, on a shelf under my feed tank. From there I have 4" PVC that carries the HP air to under the back of the arch. At that point I split into 2 lines of 3" PVC. Each has a 3" ball valve, and then each enters the arch. The AUF goes in under the base of the arch, connects to a 4" heavy ga. galv. sheet metal pipe. That pipe extends forward to about 6" from the front and I have 3 rows of 1/4" holes, one pointing up, one row faces towards the outer part of the grates. Then I have the second duct (this time only 2x2 steel tube). It enters thru the ramp floor, then splits and goes across the back, up each side, and then across only to the edge of the door. This all is at 6" below the pan. In this there is a 3/8 black steel nipple welded every 6" and it points down at 15 degrees and towards the opposite side. Originally I tested several positions on the valves, but once I got the performance at it's best I've made no further adjustments. I have the AUF valve open about 30% and the AOF valve at about 75% open. This seems to have worked the best.
I'm not sure you want to just have the nozzles across the back, you want there to be a tremendous turbulence in the firebox and I think that will only come by having nozzles facing inward from every side. I originally shut off the blower while fueling, but then my grandson forgot to one time and we noted that no sparks nor ash nor smoke came out the open door. Since then, we just turn the blower on as soon as the first gets started, and don't turn it off until shut down time, after the glowing embers have nearly all burned out.

[asknupp]

Thanks mellondome.

Dave,
My blower is similar to yours but direct drive and probably 80 yrs younger.lol your setup is what I had envisioned. Its loud so I intend to have outside and plumb it through the wall. It looks to be 4" o.d. probably use 4" rubber boot to PVC thru wall to a wye. Noticed in photo bucket you used brass ball valves. Do they make PVC ball valves that big or is there a different reason you used brass? Cheaper is the way I'm thinking is why I ask. And then from valves reduced down to 3" into two 3" steel pipe (with rubber boots) that connect to arch.

Thanks
Andy

[CharlieVT]

Old post. Scroll down for pic of my air dampers.

http://mapletrader.com/community/showthread.php?21545-Request-for-Air-Over-Fire-Pictures&p=233064#post233064

[maple flats]

My blower connects to the 4" PVC using a Fernco type coupling. All the rest til the final connection after the valves is glued PVC. For the connection from 3" PVC to the 4" galv. I just slit one side of the galv a few inches and then used a band clamp to attach. The other one it starts at 3" PVC after the valve and I used a Fernco, 3" x2" PVC coupling. The 2" end fit over the sq. tube and clamped good. If I remember I had to stretch it some to fit.