Installing forced air?!?

[danno]

I have an old, wood fired, non-air tight 30 x 8 DG. I already have a fan with a reostat (sp?) that I pulled off something else.

Is it worth installing as my evaporator is not air tight?

If I install it, where on the fire box are they installed? I was thinking on the bottom/back of the fire box so it is out of the way. But, will it blow smoke/flames out the front doors?

Also, I usually I have a pretty good pile of ash under the grates where I'm thinking of installing the blower. Will the blower push the ash away so that it will remain effective?


When I fire - I see a dramtic increase in sap flow in the float box when I'm cranking. I'm wondering if the forced air will increase the sap flow even more.

[maplehound]

Danno,
Put the air in at the back of the ash pit like you are planning. Adjust the fan so that the fire isn't blowing out around your door. You may have ash flying out at first but once your stack is heated up that should stop. You may be able to keep the fan slow at first the speed it up as the fire gets hotter. You will be amazed at how much this will increase your boil rate.
Good luck
Ron

[WESTVIRGINIAMAPLER]

It will make a big difference in boil and evap rate. You can bolt on some ceramic blanket on the inside of your arch and doors with small bolts and will help seal off the ash. Also need some type of rail gasket between pan and rails to seal the ash off there and make it more airtight. You don't have to do either of these, but it would keep the ash to a minimum. :D

[the old guy]

I HAVE THE SAME PROBLEM WITH ASHES BLOWING OUT THE DOOR OF THE ARCH ( I HAVE A 2 X 6 D&G). WHAT IF YOU TOOK A QUARTER INCH STOVE GASKET ROPE AND USED HIGH TEMP ADHESIVE TO HOLD IT IN PLACE?

THE OLD GUY

[danno]

I do have rail gasket. My leaks are around my doors. I will install the forced air and try the gasket around the doors - good idea! With more taps and vacuum and a full time job, I need to find away to increase my GPH.

Next question - pre heater. I'll start that in another thread.

[Sugarmaker]

Danno,
I have some pictures on the web site of my homemade blower. ( Picture page then click on the photo of the evaporator). Its a 550 cfm which was recommended by Leader Bought it and the 2 speed switch from Grainger. I also designed and built in a damper in the tunnel to allow additional control if the fan is to strong. Seems to work Well. I do get a little ash flying around but not that much. I burn pallets and have almost no ash below the grates, just lots of nails.
I did build custom grates and allowed room for fire brick across the front of the grates behind the doors. This seems to help. This is like firing a blast furnace.
Regards,
Chris

[archangel_cpj]

why cant it be piped right in the ash door I did this to a halfpint that flourmiller has now and she screamed?????

[danno]

I tried it in the ash door last year just to see if I would see a differance in firing. Frankly, I did not see a big differance but the ash door was also wide open and I did not try it for long. Did not want to put it there permanently because it was in the way.

[Jim Brown]

danno; I put forced draft on my W/S 2x6 and put it in the ash door. I cut a sheet of galvinized tin a little bigger than the door opening. cut a 4" hole in the center and put a gal. elbow in the hole and crimped it in . I placed three fire bricks on edge acrossed the ash pan about 1/3rd of the way in this directs the air up through the grates and allows a place behind the bricks for ashes.The fire bricks are about 2 inches from the bottom of the grates. I have the ash pan lined with fire bricks also this keeps from burning out the side if the ash pan when the rigs as running hard!I us ceramic blanket cut in strips from gasket at it seals very good no flying ash!
Hope this helps
Jim

[The Sappy Steamer]

I bought a 2x6 D&G this fall and asked the dealer about adding forced air to it. He said he strongly advises not to. He said the last guy he knows that did it, cracked the cast front to the arch. It sounds like you other guys are having good luck with it. I have it on my homemade "psychobilly cadillac" evaporator, the difference is about like when you hit the oxygen lever on a cutting torch as opposed to just the flame. The sap goes from boiling, to jumping. I don't have the guts to do it to a brand new rig after I was told it could trash the front, but I'll be going to it after I get a little wear n tear on it. Good luck Danno.
Dan

[WESTVIRGINIAMAPLER]

Dan,

You or Dannon could line the entire arch front and doors with ceramic blanket. It would keep the heat off of the doors and help keep it more airtight at the same time! :D Just some 1/8" stainless bolts and washers should hold it right in place! :D

[Father & Son]

I put a 265 cfm blower on our old 2 x 6 leader last year with a dimmer switch. This way you can adjust it so there is no ash coming out the doors. Placed it on the back of the ash pit and it made a visible difference in the boil in both of the pans :D

Jim

[WESTVIRGINIAMAPLER]

Lowes carries 5amp infinite variable speed fan controls for $ 10. :D

[danno]

Based upon these repsonses, no doubt I'm going to put the forced air in. A 2" diameter pipe comes out of the the blower I have. If I go through the back of the fire box should I just cut that in and stick the pipe under the grates or put an elbow and diffuser on the end to point the air up toward the grates and spread out the "blow". I think I know the answer to this one.

[WESTVIRGINIAMAPLER]

Keep the end of the pipe flush with the back wall of the arch so the air will spread out its maximum. If you point it up, you will have all the air concentrated in one spot and if you run the pipe very much into the arch, the air will be hitting the front of the arch/ash door.

[Parker]

If you do put in the forced air I would sugesst putting ceramic blanket on your doors,,I drilled my doors and put stainless bolts thru them then put the blanket on the doors THEN boiler plate,,,made a blanket sandwich,,if you dont use the boiler plate when you close the doors wood jams into the blanket and will tear it off eventually,,,the boiler plate on my doors is always red to BRIGHT yellow

[Fred Henderson]

If you do put in the forced air I would sugesst putting ceramic blanket on your doors,,I drilled my doors and put stainless bolts thru them then put the blanket on the doors THEN boiler plate,,,made a blanket sandwich,,if you dont use the boiler plate when you close the doors wood jams into the blanket and will tear it off eventually,,,the boiler plate on my doors is always red to BRIGHT yellow


I did the same thing except I used 3/16" SS plate and put a 1" space between the plate and door. I did not want to compress the blanket. However I an not using forced draft, I just want to keep the heat in.

[ibby458]

My concern with forced air on this rig that I bought is the grates. They're Grimm grates, and with natural draft alone, it warped rthem bad enough so that the previous owner had to replace some. I shudder to think what a strong forced draft would do to them.

On the other hand, the Leader rig I had last year had just regular factory grates, and didn't suffer a bit from a really strong forced draft. Possibly Leader grates are tougher or a better design than Grimm?

I know they make forced draft grates for my arch, but they're a bit costly. I'll wait and see how I do with just the natural draft from a 14" stack 14' long.

[Fred Henderson]

Grates have to be kept cool on one side so with forced draft they would be cool on the bottom side.

[WESTVIRGINIAMAPLER]

The prior owner probably let the ashes build up to the underside of the grates and that is what warped them. If they keep plenty of air to the underside, they will likely last for many years. Forced draft is even better for them as it keeps the underside even cooler. :D

[MASSEY JACK]

I asked Glen Goodrich about his take on forced draft. He said you want to install nozzles (3/4" pipe) about 4" apart on the ramp where it meets the almost vertical bricks that deflect the fire up into the raised flue. He said to have 2/3 of the air going into the ash pit and 1/3 coming out the nozzles on top of the fire. The nozzles will aim at a 45 degree angle toward the rear of the syrup pan. He also said to have the pipe nozzles even or just below the fire brick or they will melt off. I have seen this design in either the hurricane or inferno arches. He said the nozzles make a big difference. I had 800 to 850 degree stack temps last year and thought that was pretty good. He said he likes to see 1000 degrees on a wood fired unit. I am concerned about my front doors too. I hate to drill holes in those nice doors but I sure believe they will probably crack or distort with forced draft. They turn pretty red without it. I have seen the fire bricks on the front of the grates. What is this for? Does it help reduce the heat at the doors?

[MASSEY JACK]

Hey Parker. What is the thickness of the boiler plate you use?

[WESTVIRGINIAMAPLER]

Jack,

If they are getting red, you need to push the wood back a little. On my arch, I lay 2 bricks across the front of the grates and this keeps the fire back four or five inches and forces the air thru the fire and not blowing out the front of the grates where there is no wood. :)

[802maple]

I have to pretty much agree with Glenn about this, the only thing that we do different when we build the Instens-O-Fire arch is put even more air over the fire. We add air through the grates, in front of the fire, and behind the fire much like Glenn said. Our arches have 75% over the fire and 25% under the fire. If you are getting smoke out of the stack you have to much air under the fire and not enough over the top so that you are not getting total combustion. We also like 1000 degree temperatures in the stack. This setup would most likely have to much pressure for a standard arch though,would be my thought, but who knows

[WESTVIRGINIAMAPLER]

802,

Do you have any pipes between flames and pan or is it on both ends of the firebox and under the grates??

[802maple]

Actually the rear air is just under the flue pans at the back of the fire box which is 2/3rds of the length of the arch. and the front air comes thru the door and a channel above the door. On all of the archs that we build the air nozzles are either protected with blanket insulation or Compactible thermal refractory cement. All of the air is controlled by dampers to the directed part of the arch, although I am considering running them with electric motors

[danno]

Wow, you guys have taken forced air to a whole new level. Let me digress with a basic question. I thought my fan had variable spped, but it does not. Can I put it on a simple 110 dimmer switch to control speed, or will burn the motor out? I saw one post above where someone did that.

[brookledge]

Danno
As long as the switch is rated for the motor on your blower. Look at the spec. plate and it will tell you.
Keith

[Beth]

My husband is building me a blower, and he's telling me we need a FAN control (reostat), like for ceiling fans, which come in two or three speeds, and not a DIMMER switch just for lights. He said he tried a dimmer switch once on a rotisserie he was messing with, and the motor just sat and hummed. For whatever electrical reason, it sounds like a dimmer switch cannot work with a motor, just a light bulb. That's what he says, but it wouldn't hurt to get a second opinion!

[tapper]

Beth
Yes a fan control should do the job for you . A dimmer for a light might work also but probably wont last the season.

[Father & Son]

I ran a dimmer on mine all last season with no problems. It was controling a 265 cfm Dayton blower.

Jim

[WESTVIRGINIAMAPLER]

You can get an infinite variable speed 5 amp fan controller at Lowes for $ 9.99 and it works great as that is what I am using. I have a Dayton fan like Jim and it is less than 2 amps so you should be able to run about any size blower with a 5 amp controller. Buy 2 instead of 1 so you have a spare as they do tend to go bad sitting unused for 11 months. :D This is better than the 2 or 3 speeds in my opinion as you can get it just the right speed.

[archangel_cpj]

What about running the pipe from the front of the ash door to the bach and putting a couple of Ts in there with pipes running to the sides and drilling 1/4 inch holes in the top of the pipe?????? Would direct the air straight up and diffuse it too?????????????/

[Parker]

I saw a 2x8 that had 4-2" pipes comming out of the fan manifold going into the back of the firebox under the grates,,each pipe had a 1/2" nippel welded every 4 inches (angled to alternating sides 30 degrees or so) The nippels were about 2" long originally,,had been burned off some,,never seen it run but the opperator said it worked well

[danno]

Thanks for all the tips - forced air got installed tonight with the Lowes Fan controler. Am also going to blanket the doors.