Fan Mod Help!!

[Sailor]

The cabinet temp probe was placed just below the bottom rack in the corner between the door and side.


Meat probe was thru the top


Fan blade placement


Trying to show how I have the blade attached and how far off the wall.


Without a load the temp from start (77 degrees) to hold (255) never got above 3 degrees walking up.  Last load of pistachios that I did I had a 20 degree difference from top to bottom.  The longer they were in there the closer the temps got.  I do my pistachios at 225 and still rotate them every hr.  After 3 hrs the temp from top to bottom are close to 10 degrees apart.  I will be doing a load of jerky this morning and will try to document the temp swings.

With the fan mod my cook times are a lot shorter. 

[devo]

One thing not talked about this small fan kit is if you live any where you get below zero temps the fan will not even turn till the cabinet temp gets high enough to warm it up. This was another reason I went with a bigger fan. The small fan works but there is room for improvement. Doing your own fan mod is a lot cheaper than the $100 kit. All the parts are available from wholesalers at a fraction of the price.

[mikecorn.1]

One thing not talked about this small fan kit is if you live any where you get below zero temps the fan will not even turn till the cabinet temp gets high enough to warm it up. This was another reason I went with a bigger fan. The small fan works but there is room for improvement. Doing your own fan mod is a lot cheaper than the $100 kit. All the parts are available from wholesalers at a fraction of the price.

I read that when you wrote it. I was having that issue also. Thought it was just mine. Good now that it's warming back up.


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[mikecorn.1]

The cabinet temp probe was placed just below the bottom rack in the corner between the door and side.


Meat probe was thru the top


Fan blade placement


Trying to show how I have the blade attached and how far off the wall.


Without a load the temp from start (77 degrees) to hold (255) never got above 3 degrees walking up.  Last load of pistachios that I did I had a 20 degree difference from top to bottom.  The longer they were in there the closer the temps got.  I do my pistachios at 225 and still rotate them every hr.  After 3 hrs the temp from top to bottom are close to 10 degrees apart.  I will be doing a load of jerky this morning and will try to document the temp swings.

With the fan mod my cook times are a lot shorter.

Thanks for this post Sailor!! :)
Will play around with it when I get
Back home Wednesday.


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[Sailor]

Mixing the jerky up and starting the OBS.  Top and bottom 76 with no load.


Upper rack is in and this is the temp reading.  Got a 8 degree difference.


2nd rack was made and put in.  Got a 21 degree difference from top to bottom


3rd rack is in and have 18 degree difference from top to bottom 


4 trays are in and letting it come back to temp.


Placement of my cabinet temp probe.


Just went out to check and I still have a 20 degree difference between top and bottom.  I am not concerned with a 20 degree difference.  I don't have a blast furnace for a smoker  ;D  My main objective was to get better smoke circulation and this itty bitty fan is doing that.  It is keeping the back of the rack from over cooking and that is also good.  I still rotate the racks.  I know that it has cut the time way down to do snack stix and chubs.  Tomorrow I will do a butt and give some feed back regarding temps.  This is the 2nd load of jerky that I have done and I was happy on how the fan worked on the 1st try.

[TedEbear]

One thing not talked about this small fan kit is if you live any where you get below zero temps the fan will not even turn till the cabinet temp gets high enough to warm it up.

That wouldn't be a problem with mine since I store it in the basement until I'm going to use it.

On the blade sizes and different cfm ratings it appears that a 2.5" blade requires a bit of modification to the V-tray, from what I read.  I was wondering if mounting it on the opposite wall across from the SG would be a good idea as far as being able to use a larger blade and thus more airflow without running into any interference.  It wouldn't be pushing air toward the door but with the better air circulation I wonder if it would swirl everything around more and not really matter which direction the fan was pointing.

With the additional room in the "V" a shroud could also be added to keep the fan from blowing directly on the meat and drying it out.  Someone else had a pic of one of these in their Bradley.

2" blade - 30 cfm
2.5" blade - 45 cfm
3" blade - 60 cfm
3.5" blade - 100 cfm

Here it is:  Fan Shroud

[rigstar]

what a boat of great info about the fan mod, i was on the fence before about
doing it, now i am really unsure :-\;
Tedebear - just curious if you mounted it facing the sg would you not run the risk
of potentially blowing smoke back out thru the sg, eventhough it is above the v-tray,
or do you think that would not be a problem?
just thinking if there is smoke going back thru there it would gum up smoke pushing
mechanism and slider

[JZ]

MC - I bought 6 of those fans and they all look pretty much the same to me. Besides when I stacked 2 blades on the inside of the smoker I was still getting big temp differences. I don't have the fan not working issue with the colder temps. I have been starting mine up at -5*C and it started just fine - but I didn't get the Grainger motor or Smoke and stuff kit. I got mine from a local supplier for $31.

I might get the 2 1/2" blade, a 3" blade and the 3" that pushes out 100cfm and give them a try. The way I mounted mine I will likely loose the use of the bottom rack but thats ok since I have 7 others. I would also have to trim the vtray for the 3" and probably the 2 1/2".

Well I am off to start some sticks and will let you know how that works on a separate thread.

[mikecorn.1]

Cool. Hurry up before I get back home. Lol. :)


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[Sailor]

I ain't no rocket scientist and don't have any engineering schoolin either.  :o  I am thinking that we may be expecting too much from the fan mod and the Bradley.  The Bradley 4 rack has roughly 3 cubic feet inside.  The fan blade is rated at roughly 30 cfm.  We should be turning the air over 30 times per min.  Now you put meat in and the meat is going to absorb heat.  You got moisture in the meat that is going to absorb and evaporate and cool the inside.  The element is at the bottom and the cool evaporated moisture is being drawn up and out the top vent.  I would think that this is going to really affect the temps inside the cabinet.  The reason that I did the fan mod is I wanted to get the heat off the back of the unit and to circulate the smoke for a more even smoke.  The iddy biddy fan is doing what I wanted.  ;D

I am a thinkin that if we want even temps through out the cabinet with a load then a much larger fan set up is needed.  When I get around to building a proofer smoker I will put ductwork on the outside to draw heat from the bottom and channels between each rack so that each rack is receiving equal amounts of heat. 

For now I just don't see the need to have the temps be critically equal at every point in the smoker.  When I hang snack stixs I get closer temps because the meat is hanging vertical and the heat can move around.  I still get swings from top to bottom but I am not burning or drying out the bottom waiting for the top of the stixs to get up to IT.  I can now do a 10 pound load of hanging stixs in a shorter amount of time than what I was doing a load of 5 pounds of stixs.  Fan mod is responsible for this.  The smoke on the stixs is more even and the fan mod is responsible for this.  This is a good thing.

I do 3 pound loads of pistachios and rotate every hour and have no over roasted nuts.  Before the mod I would always have over roasted nuts to the back of the rack.  The fan mod evened out the heat enough that they roast even.  I am very happy about that.

Never did jerky before the fan mod so I am not able to compare.  What I can say is that I am getting a very even smoke on the jerky and not over cooking the rear of the racks.  I am still rotating.

I have done lots of brisket and butts in the Bradley before the mod but none since the mod.  I will be doing a Butt tonight for tomorrow's dinner and will be able to provide feedback then.

I guess the bottom line is the "I" am very happy with the mod and would do it again in a heartbeat.  It is doing what I wanted which is to get the heat off the back and to circulate the smoke.  Regardless of having equal temps at all times at every point in the cabinet my smokes are coming out better and taking less time.  ;D

[Sailor]

It has been 1 hour since the smoke has stopped rolling and I have turned the SG off.  My temps are now starting to narrow.  The probes are still in the same place.  I now have a 13 degree difference compared to a 20 plus degree difference.  I don't know if the heat from the generator has anything to do with this or if the moisture in the meat is being reduced so the heat is being more evenly distributed.

[JZ]

MC - I won't have any results for the bigger fan blades and still not sure if I will do it. Depends on how things turn out today with my sticks. If I decide to get the bigger blades it will be 2 to 3 weeks before my local Grainger store will get them in. At least that is what it took to get the last ones in.

The 5 racks of sticks have been in for about 2 1/2 hrs and the temp differences I am seeing between just below the bottom rack and just above the top rack is around 13*. When the PID ramps up to the next set point the difference increase to about 18* and then settles back into a 12 - 13* once it gets to the set point. This happens fairly quickly.

As far as the fan mod goes, we may not all have the same expectations or end goals. My desire was to be able to put whatever into the smoker, set the PID and walk away until the stuff was done, without having to rotate the racks. I don't think this fan is going to produce that. But I will have a better understanding of what it will or won't do after my sticks are done later today. Right now they are in the smoke cycle.

My sticks are racked - not hanging and maybe as Sailor points out the results may be better if they are hung.

[beefmann]

the biggest problem i see in this type of fan mod is that the fan is above the v tray. To a point it is good, however the bulk of the heat is still under the heat tray and of course the bottom will be hotter.

I  still believe that my heater fan is still better over all  for heat consistency through out the cabinet i have checked it  the temps a  while back .. once  up to temp there  was less then 5 degrees between top and  bottom  unless the  heater was on them it climbed.


here is the  link to my  mod

http://forum.bradleysmoker.com/index.php?topic=17329.0

[muebe]

Now this is just my opinion but I think part of the problem is that the small fan just does not move enough air to overcome the racks, frog mats, food, ect. The temps look even when the cabinet is empty but changes with a load. That CFM rating has to be lower when the cabinet is loaded. I think it more has to do with fan blade size than location. The whole point is to circulate the heated air in the cabinet.

I would think the larger fan blades will yield better results.

[JZ]

Here's an update on my smoke - I am not going to get realistic results today because of the wind.   :(  It has been blowing all day and once in awhile a real big gust comes along for about a minute or 2.  The outside temp is 9*C.

I was watching the therms and the temps were 10* apart and a really big blow came along and the temp on the top dropped by 10* in less than a minute and smoke was blowing out of where the SG connects to the box.  I thought my Bradley therm was going to get blown off the top of the smoker. It took quite a while for the top temp to recover from that and I am thinking it is just too windy today.