Advantage of Blower?

[SeanD]

The previous thread about using a table-top fan to increase boil rate got me wondering. I know the boil rate does go up with a AUF blower, but so does the wood consumption. Is there a certain proportional increase to both where the net result of rate and wood consumption is a wash, but a gain in time saved?

In other words, if I get 20 gph on my current natural draft and use X amount of wood per hour, would a blower give me say 20% more gph with a corresponding 20% more wood usage? So in this scenario my rate would go up to 24 gph, but it would knock off 20% (4 gallons/hr) more sap and boiling time (12 minutes/hour) from the previous rate. Therefore would the wood usage be the same per gallons of sap because at the old rate I'd have to boil longer and, as a result, use the same amount of wood in the end?

Does that make sense?

Sean

[wiam]

You will use wood faster. I do not think it will be proportional to evaporation.

[Dill]

One big advantage to a blower is how much faster I can get up to temp. I put some wood in, some cardboard then some more wood. Light the cardboard, close the door and fire up the blower. The fire takes right off.
I haven't done the math but I can tell you both the evaps that I've had boil much harder and faster with the AUF, enough that I don't worry about the added wood consumption.

[SeanD]

Do you guys have a sense of what kind of a rate increase you have gotten from just AUF?

Sean

[buckeye gold]

I have records that show an over all increase of 29% after I added forced draft or AUF. As someone else said you get to full fire and heat a lot faster. I may burn more wood but 1/3 less time boiling, it a small price. Especially since my wood is free.

[RileySugarbush]

It really depends on too many factors to estimate. How good is your natural draft now?

What I can say is it is fantastic compared to natural draft and any more wood you burn will be worth it. No more lazy boils.

The best way to gage efficiency is to get a good probe type stack thermometer and get an idea of how much waste heat is going up the stack.

[Starting Small]

I am getting a 2X3 with a blower from Bill Mason and he said that it should add about 3 gph. If it normally does 7-9. it may get it to 10-13. Might be a little high estimate but gives you an idea from a proportional standpoint. Not sure about wood consumption.

[SeanD]

Yeah, I know it's hard to nail down, but if there is a ballpark of increase it can help me measure whether it will be worth my while. 25%-30% is something to think about especially if I get tight on time. I should have also asked how much more wood people go through, too but then again I have the similar problems figuring out my own current usage. I can tell you how much wood I used last year for 30 taps, but that I won't really be able to compare it to this year's usage because I'm going to 90 taps. I make too many changes every year to make some judgements. At least this year I'll be on the same rig with the same pans as last year. I think that is a first for me.

I don't know how to truly judge how good my natural draft is other than the wood burns cleanly and I'm firing every 6 min. My probe stack thermometer at the top of the base stack would get up to 800 deg. and I'd have a good boil. I think I cranked it up a couple of times, though I don't remember how high. At some point I turned my stainless stack copper from the base right up to the cap (18').

The boil wouldn't last the full 6 minutes. After a few firings I really didn't need the timer any more, I'd just see the boil start to die from the back forward. I got pretty good at guessing how much time was left on the timer. Anyway, I think my natural draft is okay, but let me know if you are picking up on something.

Thanks,
Sean

[RileySugarbush]

800°F on a probe thermometer is not very high, so you are pretty efficient, and could trade that efficiency for a higher rate. Magnetic stack thermometers read much lower than probe thermometers.

[wiam]

After a few firings I really didn't need the timer any more, I'd just see the boil start to die from the back forward. I got pretty good at guessing how much time was left on the timer.

Thanks,
Sean

If you see the boil die down you're not firing often enough.

[Starting Small]

So you do not leave the blower on constantly is that correct?

[adk1]

I would imagine that every time you fire (open the doors) you shut the blower off

[Dill]

I leave it on. Usually its turned down enough that flames and sparks stay in the arch but looking at all the burn holes in my clothes most of the time I live dangerously.

[adk1]

wow. I bought a rheostat for mine that has an on/off toggle switch. I plan on shutting it off each time.

[RileySugarbush]

My suggestion: On/off switch for firing, in case you want to save your eyebrows. Forget the rheostat and adjust blower with a inlet baffle/damper. simple and effective.

[wiam]

I do exactly as Riley does.

[Daren]

I dont have AUF and fire about every 6 to 7 min depending on type of wood with each firing. I cant say I ever "see" the boil drop, but you can definately hear a slight decrease in the sound of the boil. The unfortunate thing is that it often needs a firing just as the temp indicates a draw. Now do you draw and fire later or just crack er open and fire through the draw(what I usually end up doing and checking with the hydrometer to see if I can keep it open or need to draw heavy for a bit.

[wiam]

I dont have AUF and fire about every 6 to 7 min depending on type of wood with each firing. I cant say I ever "see" the boil drop, but you can definately hear a slight decrease in the sound of the boil. The unfortunate thing is that it often needs a firing just as the temp indicates a draw. Now do you draw and fire later or just crack er open and fire through the draw(what I usually end up doing and checking with the hydrometer to see if I can keep it open or need to draw heavy for a bit.

I draw when thermometer says draw and fire when timer says fire. If they overlap that's the way it goes. I have seen some that will absolutely not fire when near drawoff. I have also seen them not get quite to temp for draw and by then fire is low so it takes longer to get back. If temp drops a little when firing the syrup is not going anywhere. It will come out sometime.:lol:

[Starting Small]

When you say fire do you mean add more wood?

[wiam]

When you say fire do you mean add more wood?

That is correct.

[wcproctor]

Just hooked my home made blower up and works good5247

[rookie]

I would imagine that every time you fire (open the doors) you shut the blower off

If I didn't shut off my blower, i'd burn my shack down :o

[sbingham]

I can relate to many of the posts on this subject. I started out with a 2x4 flat pan and was lucky to get 8 gph evaporation, cobbled up a make-shift blower and was able to get about 10gph.
Sold that unit and bought a 2x6 unit from WF Mason with a blower, we average 16-18 gph now. It may consume a bit more wood, but my days are now 8-10 hours instead of 16 hours+.
I will gladly trade the extra wood for the savings in time. I rigged a baffle on the blower to control the air coming in to the fire box and it works very well.
Judging by the burn holes in my cap, sweatshirt and vest from last year, I need to wire in a switch to shut down the blower while firing.