Air Inlet design question ???

[TerryEspo]

Good Mornig All:

Last night looking over my new arch build I got to thinking about the air coming in to my stove. I do have a grate now above the bottom of the firebox, approx. 4" above the bottom of the box. I can now join the AUF group,lol.

I still have to design and build the whole front of the arch so whatever I want I can can do.

My question is for the air coming in under the fire. Does it matterhow the air gets in ? Is it better to have two holes on each side, left and right or just a larger hole in the center and and a way to adjust them?

Maybe over thinking it, but what about a pipe drilled with multiple holes that runs the length of the firebox, kinda like the way a propane BBQ gives propane underneath ?? Doing that would allow a little blower maybe down the road. That pipe inlet would stick out the front of the stove just below the door openng.

I just dont know if there is a "science" to how you get/allow air into the firebox. Ice fishing stoves and tent stoves just have a centered basic slider type inlet and that would be fine too !!

So, if anyone could tell me the best way , if there even is a best way to design my AUF, ( love saying that),,,,,please input is welcome.

Thank-you.

Terry

[JAMIE]

Terry,

Mine comes in from the back of the fire box and is mounted under the arch.One hole in the center.Set the blower back a little ways and duct up to the arch,it does not have to be set back much.My arch uses a squirrel cage blower and also has a speed control so once shes up and running you can fine tune it in.You get a big at a boy for even attemting a project like this...just something out of my league!!!

[TerryEspo]

Hi Jamie:
More darn snow for us,,,wow. Thanks for your reply.
I went for a coffee to the garage and took some pics of where I,m at with the arch. I dont know if I am going to install a blower or not, just was thinking about if later I wanted to, somehow prep it now while building.658465856586
Everything in the pics is just sitting there, nothing fastened so if things looks crooked, its cause they are !!

As you see in the pics, I have lots of room the allow air in, just wondering is there is a science to it ?

Thanks.

Terry

[maple flats]

My under fire air comes in from the back, at floor level. I just have a 4" stove pipe with 3 rows of 3/8" holes drilled, 1 top center and one each side pointing towards it's side of the pan. Works good for me. With just 4" under the grates, just try to flatten it to an oval before drilling the holes.

[TerryEspo]

Hey Flats....Is there a particular reason that your air comes in from the rear ? I kinda wanted my air to enter from the front so I can control the amount of air in, it would be a pain to have to bend around the back each time I wanted to adjust the incoming air.

So I am guessing that your 4" pipe runs under your entire grate ? I do understand your hole pattern, just not sure how long the pipe is.

Thanks.

Terry

[ACollette]

66316630

Terry,

Here is a photo of my homemade arch. As you can see I have air under fire in the front like you were hoping to do. What I did was take 1/2" angle iron and weld it to the front of my arch to create a track to capture my sliding "ash" doors. These are 1/2" thickness steel with handles welded on them. They slide in the tracks much like a sliding glass patio door. I can open them wider to allow more draft or close it up. To add my air under fire set up, I took a squirrel cage blower mounted it in a wooden mount and built a sliding air control on the right side. The slide allows me to increase or reduce the amount of air entering the center of the blower. If I did not have this, I would be pushing 300 cfm into my arch and it blows my heat out my stack. My arch grates are inverted 1 1/2" angle iron seperated at 1/2" increments. The look essentially like VVVVV, the ash from the fire box fills the angle iron so the heat does not warp the steel. I built an adaptor (out of 1/2" steel with a 4" male flange in the center) that slides into my ash door slides that receives my 4" vent pipe from my blower. The adaptor also has flat steel to cover each both the left and right sliding ash doors to prevent hot ash from escaping. You can also see that I wired the blower with an on/off switch right at the blower motor. This allows me to shut the blower down when I load the arch.

The blower set up has dramatically increased my boil. Without the blower on and just the ash doors open, my stack temps drop significantly and my boil reduces to a roll. I can maintain 800 degrees stack temps consistently with the blower and the sap boils violently.

I hope this helps. Have fun.

Aaron

[Flat Lander Sugaring]

Hey Flats....Is there a particular reason that your air comes in from the rear ? I kinda wanted my air to enter from the front so I can control the amount of air in, it would be a pain to have to bend around the back each time I wanted to adjust the incoming air.

So I am guessing that your 4" pipe runs under your entire grate ? I do understand your hole pattern, just not sure how long the pipe is.

Thanks.

Terry

If I'm the flats your talking to mine comes in the rear because thats how it was shown to me and thats how all the big guys do it. If it comes in the front you will have to be careful not to hit it walking around, feed the arch with wood etc. my blowers are in the main part of garage so I dont have to listen toi them.

[TerryEspo]

Hi Flat Lander,,,,yes, it was you I was asking.
Thanks for telling me. It makes sense about air entering from the rear.

After eading what Aaron posted about his blower giving him 800 F stack temps, wow is that impressive. I was thinking about no blower this season, just run it as is and see, but now must reconsider.

Thanks guys.

Terry

[Flat Lander Sugaring]

you gotta have forced air otherwise its like watching paint dry

[Flat Lander Sugaring]

you gotta have forced air otherwise its like watching paint dry
with no forced air you do have a couple positives;
1. drink more beer over a longer period of time
2. evap rate is much lower which slow down bo bo's that can happen

[TerryEspo]

Well, I have it figured out with my arch. With all the great advice here at Male Trader, I am going with a front drawer type ash pan below my door and putting a small blower at the rear of my firebox.

I had a squirrel cage blower and didnt even know it.

We had an inflatable pumpkin (halloween decoration) that had a blower in it, ripped the pumpkin apart and now have a blower, lol. The plan is to blow from the rear as to make the air do a 180 degree turn before going out the stack. I will now put firebricks on my door for when the blower is blowing.

I am thinking correct about the air having to turn around to exit,,,right ??? Most efficient??

Getting excited to compare a boil and stack temps with and without the blower. Arron C. posted his blower set-up and I love the idea of being able to control the amount of air blowing, I will just place the blower, not bolt it in place, and be able to slide it forward and back depending on how much air I want going in. Thanks Arron for that.

I hope to get some pics soon, maybe able to work on that this eve.

Thanks all.

Terry

[JAMIE]

Terry,
You may want to have a way to either stop or slow your blower down when you fire the evaporator or you may get a face full.Just a thought.This whole blower thing is new to me also. I have a speed control on mine.

Jamie

[TerryEspo]

I am thinking to just shut the blower off anytime I open the door. I can also just move the blower out of the way and cap the opening.

I did get the blower installed this eve. My son helped and had a ball helping dad. I didn.t get a pic yet, forgot camera but will. I put my pan on (dry), closed the front where the door should be and put the blower on. I wanted to see if I could feel air coming from the top of the stack. I did feel some, not tons though. It would flap a tissure for sure, just not what I would call "blowing" out the stack. I did not put gasket aROUND THE PAN, THE FRONT WAS JUST COVERED WITH A LARGE STEEL PLATE CLAMPED IN PLACE SO I CAN SAY I DID HAVE MAJOR AIR LOSS TOO. Oops, I had caps on, sorry for that.

Can anyone tell me how much air I should be feeling at the stack end with the blower going ? Mabye my blower is underpowered? There is lots of air circulating in the firebox area. I put tissues in the firebox and they jump around, flop, float etc. Maybe I do have enough of a blower? I need to get a door on and burn wood to really see.

Anybody able to tell me how much air I should be feeling or any other test ??

Thanks.

Terry

[Flat Lander Sugaring]

you wont get that much flame in your face unless you just loaded up arch with lathe from an old house and you open the door to fire. If I can find video I will post. Remember the more even and consistant you keep everything the better it will go.

[Flat Lander Sugaring]

this what it looks like when you fire with lathe and dnt shut fans down, untypical.
http://i40.photobucket.com/albums/e234/poultneyfiredog18/Sugaring/bigflame2.jpg

http://i40.photobucket.com/albums/e234/poultneyfiredog18/Sugaring/bigflamessugaring.jpg

[Flat Lander Sugaring]

heres a video of doors open and auf/aof on
http://s40.photobucket.com/albums/e234/poultneyfiredog18/Sugaring/?action=view&current=MVI_1926.mp4

[maple flats]

Hey Flats....Is there a particular reason that your air comes in from the rear ? I kinda wanted my air to enter from the front so I can control the amount of air in, it would be a pain to have to bend around the back each time I wanted to adjust the incoming air.

So I am guessing that your 4" pipe runs under your entire grate ? I do understand your hole pattern, just not sure how long the pipe is.

Thanks.

Terry

I have not found it necessary nor desirable to keep adjusting the air. I did adjust the first few times I fired, but within 3 or 4 firings I had gotten it right based on performance. That was a few seasons ago. Since then the valves I have (2 @ 3" ball valves, one for over fire and the other for under fire air, both valves control the high pressure air from 1 blower, after splitting from 1 pipe 4" diam. into 2 pipes of 3" diameter) have been in the same position, unchanged over the seasons. At first I shut off the high pressure blower fearing flames or sparks would shoot out the door when fueling. Then one time my grandson forgot to shut the blower off and there was nothing coming out the door when open, except heat. I then tested things by lighting a piece of paper, extinguishing it and seeing what the smoke did. To my surprise the smoke still showed good draft into the open door. Since that back in the first season I had this blower, I have not shut off the blower to fuel. When starting the fire I do not have the blower on, I lay up the fire half full with no kindling. Then I light it with a 500,000 BTU weed burner torch at about half force. It roars but not like it will when the gas valve is full open. When lit and burning good, I shut off the torch, close the doors and turn let it get fully involved, then I turn on the blower. After that the blower stays on until about 20-30 minutes after last fueling at shut down. This works good for me.
I will say, that since I have new (3" taller flues) pans I likely will re study the air valve adjustments, but once I find the best setting they will again remain for seasons to come.
I suggest you do similar and run such a test when running full force. I believe it should be the same results.
As for feeling air out the stack, I have no idea, but I have opened my rear clean out with the blower running and put my hand in to feel, I can feel air flow but barely. I think it is just because the 4" high pressure air flow is spread out to a space of about 31" wide by 11" deep, before entering the base stack and reducing 6' higher to a 12" stack.

[Azitizz]

with no forced air you do have a couple positives;
1. drink more beer over a longer period of time
2. evap rate is much lower which slow down bo bo's that can happen

Well, actually one more big positive is that you can put your boiler wherever you want... no need for electricity:)

[Flat Lander Sugaring]

I pressurize the whole area under the grates. My very first prototype AUF (1995) was a piece of 4" emt conduit with slices down it. I found more air at the end of the conduit than any where else, so I cut slits across the conduit and slid air deflectors down and welded them up. I did like 3 or 4 of them, the first one went down the most and each consecutive one a little less maybe it was reversed I cant remember.

Hey Flats do you think a manometer in the stack wold help adjust the air flow better? I thought I read something about them and draft on a wood stove or boiler.