Fan Mod Help!!

mikecorn.1 · March 09, 2012, 09:44:05 AM

Quote from: JZ on March 09, 2012, 09:39:33 AM
Ok I put the second blade on and fired it up. I had 3 temp gauges going 1 at the top, Auber PID in the middle and third one just above the vpan (about 3"). I set the PID to 200* and here are the results.

The middle and top readings stayed within 2 degrees of each other. The bottom one was different story. The temp difference between it and the other 2 was around 25* - 30* while the box was heating up and when it got to the set temp the difference started to drop. By the time the whole thing settled in for awhile the temp difference was around 16* - 18*. I did not check the temps at the back or front of the box and will go and move the probes to see if that makes a difference. NOTE THAT THIS IS WITHOUT A LOAD.

My conclusion is that the more heat that is required to maintain the set temp the more the variance will be. Once the set temp has been achieved it will take less energy to maintain it it and therefore the internal temps will be more even. Adding a large load of meat is going to mean more heat is required and as the temp differences will be greater because the elements will be on longer. Also as Sam3 pointed out the temp variations will be less at lower temps because less energy is required to maintain the lower temps.

I like Devos solution but not sure I want to take that step yet. Might just carry on with the current setup, since it is already installed.

By what you just posted, I am not adding a second blade, I have the exact same results with one blade. We might as well have been doing all the testing on cloned bradleys (I mean same readings, no joking) :o

JZ · March 09, 2012, 10:17:23 AM

Moved the probes as follows. Bottom one moved closer to the back wall and still just above the vtray. Middle one (PID) stayed in the middle of the box. The top one moved closer to the front and still near the top of the box. This time the temp differences were more pronounced. The difference between the bottom and the middle were up to 40* while the box was coming up to temp and the difference between the middle and top front were up to 10*.

Once everything settled in the temp differences between the bottom and other 2 was around 10*. Again this is with an empty box.

I am doing some stick tomorrow so will get some real world results and let you know how it goes.

mikecorn.1 · March 09, 2012, 10:50:07 AM

Quote from: JZ on March 09, 2012, 10:17:23 AM
Moved the probes as follows. Bottom one moved closer to the back wall and still just above the vtray. Middle one (PID) stayed in the middle of the box. The top one moved closer to the front and still near the top of the box. This time the temp differences were more pronounced. The difference between the bottom and the middle were up to 40* while the box was coming up to temp and the difference between the middle and top front were up to 10*.

Once everything settled in the temp differences between the bottom and other 2 was around 10*. Again this is with an empty box.

I am doing some stick tomorrow so will get some real world results and let you know how it goes.

Good luck, will checking in to see. I was constistant at 130 and as I went on to 170 it kep getting further apart. At 170 it was 10 degree different. This on on my last snack stix smoke. With the fan on. Stick hanging with plenty of space in between especially in the middle, so that the air could circulate. 5 lbs.

Salmonsmoker · March 09, 2012, 05:44:25 PM

Mike, if I understand your post correctly, the fan is blowing towards the door. If that's the case, there are others that have reversed the rotation of the motor so the fan draws towards the back of the cabinet. The fan is set about 1/2" away from the cabinet back. Reportedly, the circulation and temps are more even.

mikecorn.1 · March 09, 2012, 06:07:06 PM

Quote from: Salmonsmoker on March 09, 2012, 05:44:25 PM
Mike, if I understand your post correctly, the fan is blowing towards the door. If that's the case, there are others that have reversed the rotation of the motor so the fan draws towards the back of the cabinet. The fan is set about 1/2" away from the cabinet back. Reportedly, the circulation and temps are more even.

Yes towards the front. I read somewhere on how to reverse it. Anyone know where the thread is? :)

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kickedback · March 09, 2012, 06:32:37 PM

I put the 2.5 inch fan blade on and haven't had any problems. I only checked temp difference once and it wasn't way off, 3-4 degrees. I had to notch out the v-tray and it clears the 1st rack. It doesn't seem like it is pushing alot of air, but I don't have to rotate racks and it pretty much cooks even top to bottom. Hers's a couple pictures. Hope this helps.

mikecorn.1 · March 09, 2012, 06:40:38 PM

Quote from: kickedback on March 09, 2012, 06:32:37 PM
I put the 2.5 inch fan blade on and haven't had any problems. I only checked temp difference once and it wasn't way off, 3-4 degrees. I had to notch out the v-tray and it clears the 1st rack. It doesn't seem like it is pushing alot of air, but I don't have to rotate racks and it pretty much cooks even top to bottom. Hers's a couple pictures. Hope this helps.

This is the second time I've read about the 2.5". Kinda figured that it wouldn't fit in place of where the 2" is without cutting something. Yep, that's the same place mine is. Did you center the hole for the 2" and replace with the 2.5"? So you didn't have to cut the tray, just the V-tray? What temps where you looking at that were even (2-3 off)? Thanks for the info BTW :)

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Mr Walleye · March 09, 2012, 07:01:37 PM

Mike

I originally reversed mine to pull air to the back of the cabinet. This cased even more heat at the back of the cabinet. I reversed the motor back to run the fan blowing the air towards the door and I had much better results.

Here's a few things to look at:

- make sure the fan is spaced away from the back wall as far as possible. If the fan blade is right up against the wall it will have no intake air. Mount the collar of the fan towards the back of the cabinet, this will help get the blade as far as possible away from the wall.

- I'm not sure you are using the same blade that I am but I saw a good improvement on mine and it's been that way for a number of years. Is it perfect... No, but it's vastly improved.

- Tweak the openings in the V-Pan. Slightly open the front half of the vents and slightly close the rear vents. This helps move some of the heat to the front of the cabinet.

- As a last resort, try tweaking the pitch of your fan blade to increase the amount of air flow.

Mike

mikecorn.1 · March 09, 2012, 07:31:34 PM

Quote from: Mr Walleye on March 09, 2012, 07:01:37 PM
Mike

I originally reversed mine to pull air to the back of the cabinet. This cased even more heat at the back of the cabinet. I reversed the motor back to run the fan blowing the air towards the door and I had much better results.

Here's a few things to look at:

- make sure the fan is spaced away from the back wall as far as possible. If the fan blade is right up against the wall it will have no intake air. Mount the collar of the fan towards the back of the cabinet, this will help get the blade as far as possible away from the wall.

- I'm not sure you are using the same blade that I am but I saw a good improvement on mine and it's been that way for a number of years. Is it perfect... No, but it's vastly improved.

- Tweak the openings in the V-Pan. Slightly open the front half of the vents and slightly close the rear vents. This helps move some of the heat to the front of the cabinet.

- As a last resort, try tweaking the pitch of your fan blade to increase the amount of air flow.

Mike

Holy Carp!! What, where you in my garage this morning with me hiding in a corner? LOL. Everything you just said, I did. Must be cause were Mike and great minds think alike!! ;D.

All joking aside, everything you said, I did. Not on thing did I miss from what you mentioned. The last thing I tried was the closing and opening of the vents on the v tray and it helped somewhat. I was doing all this at the 225 range. As stated by other members, it's easier to stabilize at lower temps. At least with this 2" blade.

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mikecorn.1 · March 09, 2012, 07:57:25 PM

Quote from: rigstar on March 09, 2012, 09:32:57 AM
Quote from: mikecorn.1 on March 09, 2012, 09:20:06 AM
Quote from: Sam3 on March 09, 2012, 08:43:18 AM
Mike, perhaps the higher temps that you are running it might be adding to the difference between top and bottom. Obviously that element is very hot and stays very hot.

Have you tried it at a low temp like 130 dgrees and checked to see what it was? I don't go over 170 with my OBS and have had no problems thus far.
Sam, now that i think about it, yes, when I was making sticks, the temps were even and or alot closer together when I was starting at 130. Even took a pic of it. When i got to 170 to finish, the temps were about 10 off from top to bottom. Ive been at this all morning trying different things. I was even going to buy an extra fan blade here locally for around $4 till I took my fan off and tried fitting both blades on the shaft inside just to see if they would fit. NOT >:(!! I put both blades on while the fan was off the smoker to see if I could tell the difference in flow. Cant really tell, thats not to say that once its inside mounted it will make a difference. JZ is also tinkering with his. Been PM'ing with him this morning. Hopefully he has better luck. :)

hey mc did you happen to look at the post by Docz, i believe he had to add a piece of
dowel and then siliconed the 2 fans together to make them fit on orginal shaft,
i am thinking that is because like you said the 2 won't fit on orginal shaft alone.
just another thought for you

Thanks for the info. Im not gonna mess with the 2 blades after seeing what Jz posted. Probably try the 2.5" ;D

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Sailor · March 09, 2012, 08:14:44 PM

Mike, sorry to see that you are having problems. I am using the blade that came with the kit. I have the coller where the set screw is pointing to the door. I don't seem to have any trouble with maintaining even temps. After reading this thread I went out and fired up the OBS with out a load as I wanted to season the new Amazin pellet burner I just got. Temp outside was 77. Got a probe in the top about inches down and put a rack in the bottom and have the cabinet probe hanging to just below the rack to the front. As the OBS started to heat up I never got more than 3 degrees difference between the top and bottom. I held the temp at 255 degrees for 2 hrs and maintained a 1 to 2 degree difference between the top and bottom. I sure hope that you can get it figured out. I am glad I did the mod and wish that I would have done it sooner.

mikecorn.1 · March 09, 2012, 08:39:08 PM

Quote from: Sailor on March 09, 2012, 08:14:44 PM
Mike, sorry to see that you are having problems. I am using the blade that came with the kit. I have the coller where the set screw is pointing to the door. I don't seem to have any trouble with maintaining even temps. After reading this thread I went out and fired up the OBS with out a load as I wanted to season the new Amazin pellet burner I just got. Temp outside was 77. Got a probe in the top about inches down and put a rack in the bottom and have the cabinet probe hanging to just below the rack to the front. As the OBS started to heat up I never got more than 3 degrees difference between the top and bottom. I held the temp at 255 degrees for 2 hrs and maintained a 1 to 2 degree difference between the top and bottom. I sure hope that you can get it figured out. I am glad I did the mod and wish that I would have done it sooner.

Well F*#k me, I just dont understand what is going on with mine and other member that are having the same problem. Thanks for rubbing it in ;D ;D. Were did you place the bottom probe, was is directly in front of the fan flow or off to the side? Thanks for the post.

JZ · March 09, 2012, 10:01:54 PM

WTF - why is mine and Mikes so much different. We are all using the same fan blade, it turns at 3000 rpm, it is mounted at the back of the smoker and above the vtray. So how can we get such different results? I don't get it. :o

I did see that Sailor has his blade reversed to mine (ie the collar is at the front - which would mean that his blade is closer to the back of the smoker). But Mike (Mr Walleye) said he had better luck with his further away from the back wall.

I think I am going to hook up a leaf blower to this thing and be done with it. LOL ;D ;D

TedEbear · March 09, 2012, 10:45:53 PM

Quote from: JZ on March 09, 2012, 10:01:54 PMI think I am going to hook up a leaf blower to this thing and be done with it. LOL ;D ;D

LOL - you'll shoot those butts across the yard.

mikecorn.1 · March 10, 2012, 05:29:25 AM

One last comment before I hit the road on a 5 hr road trip.
Does anyone think that it could possibly be the blade itself. They are so cheap and mass produced that they could be different as far as how they are angled or curved. Both the ones I have are slight different. When you look up close. Just a thought.

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