Fan Mod Help!!

mikecorn.1 · March 10, 2012, 01:27:33 PM

Woe lot of good info since I left this morning. Thanks for all the input. Gonna wait to see if JZ has any luck with a bigger size. :)

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Sailor · March 11, 2012, 09:41:15 AM

I put the Butt on last night at 10pm. Forgot all about the time change so basically it was 11pm :o At any rate I preheated to 225 and top and bottom were spot on. Loaded the 10 pound Butt and temps came down but both top and bottom were within 2 degrees of each other. I used the PID meat probe to stick in the meat so broke out the maverick to get the top temp readings. I rolled smoke for 4 hrs and changed the water and went to bed at 3am with both top and bottom reading 225. This morning I changed out the water again and Butt was at 150 and top and bottom at 225. It is now 12:30pm EST and I upped the smoker to 250. The Butt is at 171 and top and bottom temp is at 237 with 1 to 2 degree difference.

What does all this mean? Well, I think someone already said that the use of frog mats and having stix and jerky laying horizontal may be the problem. I think I tend to agree with this. With a empty cabinet the fan keeps temps with 2 degrees. When I am doing nuts or jerky I get a 20 to 25 degree difference. I put a Butt in and keep within 2 degrees.

Personally I think the small blade is doing what it is intended to do. We are moving air. It may not be enough for some but for what I want it to do it is just fine. I personally will not be making any adjustments or adding any blades or putting bigger motors on. I am very happy with what I gots. Just thought I would give my results.

Yeah I know.....no pics didn't happen ;D Will go out and shoot a couple of shots and post in another thread. Was to busy last night to get the prep shots.

mikecorn.1 · March 11, 2012, 11:15:15 AM

Quote from: Sailor on March 11, 2012, 09:41:15 AM
I put the Butt on last night at 10pm. Forgot all about the time change so basically it was 11pm :o At any rate I preheated to 225 and top and bottom were spot on. Loaded the 10 pound Butt and temps came down but both top and bottom were within 2 degrees of each other. I used the PID meat probe to stick in the meat so broke out the maverick to get the top temp readings. I rolled smoke for 4 hrs and changed the water and went to bed at 3am with both top and bottom reading 225. This morning I changed out the water again and Butt was at 150 and top and bottom at 225. It is now 12:30pm EST and I upped the smoker to 250. The Butt is at 171 and top and bottom temp is at 237 with 1 to 2 degree difference.

What does all this mean? Well, I think someone already said that the use of frog mats and having stix and jerky laying horizontal may be the problem. I think I tend to agree with this. With a empty cabinet the fan keeps temps with 2 degrees. When I am doing nuts or jerky I get a 20 to 25 degree difference. I put a Butt in and keep within 2 degrees.

Personally I think the small blade is doing what it is intended to do. We are moving air. It may not be enough for some but for what I want it to do it is just fine. I personally will not be making any adjustments or adding any blades or putting bigger motors on. I am very happy with what I gots. Just thought I would give my results.

Yeah I know.....no pics didn't happen ;D Will go out and shoot a couple of shots and post in another thread. Was to busy last night to get the prep shots.

Good info, thanks. :) I BELIEVE YOU, even with no pics:)

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pmmpete · March 15, 2012, 10:37:45 PM

I suspect the reason some people have uneven temperatures in their smokers is because they put too much meat or sausage in their smoker, either sausages, jerky, or fish on racks, or hanging sausages. There needs to be enough room between the meat products for the smoke to circulate. You could put several temperature probes in your smoker and experiment with different densities of meat, possibly using pieces of 1"x2" wood or pieces of heavy aluminum foil to substitute for meat products. You could start by measuring the temperature with empty racks, then measure with lightly loaded racks, medium loaded racks, and heavily loaded racks. That experiment might give you a feel for how much room you need to leave between the meat for air circulation.

I know that some people have reported uneven temperatures with empty racks. I suspect that they need a bigger fan, or a second fan at a different location in the smoker. The temperature certainly isn't going to get more even when you add meat to the racks.

Rider14 · October 02, 2014, 10:32:33 PM

Thread resurrection!

Question for those of you with the fan mod...

The moving air hasn't caused any ash to fly around in the smoker? Like the idea, but don't want to get ash on the meat.

Also - have any of you tried the cylindrical fan blades that don't push air forward or back, but 360 degrees out perpendicularly to the fan shaft? That might do the trick not sure if it would even need a shroud/shield, and would not pull heat to the back (eliminating need for exterior cooling fan...)

Any comments/suggestions appreciated.

- Dan

tskeeter · October 03, 2014, 09:16:09 AM

Rider, don't have a fan mod, but here are some thoughts on your questions.

In a Bradley, ash wouldn't be a problem. Pucks do not burn to ash. They burn to the point of carbonization. Then pucks are discharged from the puck burner into a water filled puck bowl while they are still intact in a puck form.

I think the use of fan shrouds is as much a function of where the fan mods are usually located (below the bottom food rack) as they are a function of the style of fan used. Without a shroud to control and direct air flow, I'd think that any fan would have a tendency to stir a small pocket of air, rather than circulate air thoughout the smoker cabinet. I remember seeing pictures of a fan mod that used a squirrel cage fan, and the person who did the mod built a shroud to control the air flow.

The cooling fans on some fan mods may be a bit of overkill. The back wall of the smoker is insulated, so any heat a fan motor is picking up from inside the smoker should be coming from the motor shaft, not through the wall of the smoker. As forum members engineer things like fan mods, they tend to err on the side of caution. Since heat is bad for electric motors, installing a cooling fan helps ensure that the fan motor won't overheat. Don't know if it needs a cooling fan. But, for a few bucks, it's cheap insurance that the mod won't have to be rebuilt due to a motor failure.

Rider14 · October 15, 2014, 10:53:04 PM

I hear you on the exterior cooling fan, just means I need a longer shaft to accommodate both blades.

I've done some testing with my maverick and the Auber dual probe PID and the heat in the back (and bottom, bit more in the back) is higher than the front. I think the fan location of just below the bottom rack in the center of the back wall is the best place for evening out the heat.

Just bought the 900w element, now trying to find a suitable motor.

- Dan

dave01 · October 16, 2014, 08:49:00 AM

Rider, this is what I did to mine and it works great. I pull the v tray as far forward as I can before closing the door, that way the heat goes right up to the fans to be distributed. I used 2 1/2" blades from grainger.

Good luck, Dave

Rider14 · October 16, 2014, 12:13:25 PM

Dave - that looks like an excellent set up. Any chance you could post up the fan motor and blade parts you used? Did you also use the original heat shroud over the 900w element? Maybe also provide a pic of the motors mounted to the back?

Any help appreciated - going to pull the back off and try to install the 900W element over the weekend, and will get more familiar with the parts to plan for the fan mod(s).

_ Dan

dave01 · October 17, 2014, 05:14:40 AM

Rider,

The fan motors I used are Dayton 4M077D. The blades are aluminum 2 1/2" clockwise. I got everything from Grainger. Total cost was about $100.00
The heat shield is used now on the edge of the bottom tray just to keep droppings off the fan blades and direct them to the drip pan.
I mounted theaters into 2 steel electrical boxes and after centering the motor shaft in the hole just drilled though the box in all for corners through the smoker. You can see the 4 bolts around each motor in the photo. The 900 watt heater is just mounted to 1/8 aluminum and I used the existing wires.

Let me know if you have any other questions,
Dave

tskeeter · October 17, 2014, 09:48:14 AM

Dave, has you looked at your heat distribution with your dual fan mod? I'm still chewing on Rider's fan shroud question and trying to figure out if fan shrouds are necessary, a good idea, or overkill.

dave01 · October 17, 2014, 10:21:38 AM

tskeeter,

on the rack above the fans I use the old heat guard to keep drippings from hitting the fan. No fan shroud. I leave the drip pan all the way forward so that the heat can come up the back wall behind the fans, it seems to be the fastest way to distribute it. I have smoked quite a few racks of ribs and fish and have never had to rotate racks, everything is done at the same time.

Dave

tskeeter · October 17, 2014, 04:40:41 PM

Thanks Dave! Your's is the first dual fan set up I've seen. I've been kind of looking for something to even out the temp distribution in my six rack and it looks like your solution would do the trick with minimal fabrication effort.

Did you do something to beef up the the back of your smoker as you mounted the fan motors and their boxes? Or did you find the back wall of the smoker, combined with the back panel were heavy enough to provide adequate support for the weight you hung on them?

dave01 · October 18, 2014, 04:31:01 AM

tskeeter,
I didn't do anything with the back of the smoker but if I did it again I would beef up the back a little or cut bushings to fit over the bolts between the inner and outer walls of the smoker. It would make it easier to tighten the motor down without throwing the shaft out of alignment. Either way it's not a hard mod to do.
Dave

tskeeter · October 18, 2014, 12:06:57 PM

Thanks, Dave. Bushings is an option I hadn't thought of.