Fireboard, Modified Backwoods G2 Chubby, and Fans...long and boring...

[G'Pa]

I bought a used Backwoods G2 Chubby to cook on, while I wait for my custom Cascade Smokers cooker to get here.

I did some modifications to the G2 to not have to cook with water, and deal with the subsequent mess. I left the deflector plate above the charcoal basket in place, left the water pan in place but filled it with 3" of 2100 degree ceramic insulation that I wrapped in 2 layers of aluminum foil. Then I put in a 3/16th steel plate, sized to the bottom of the cooking chamber, on top of the water pan, and then installed a stainless steel sheet pan, sized to the bottom of the cooking chamber, on top of the plate, to catch drippings/grease from above. The bottom grate still sits on top of the drip pan without issue. I had to bend the long edges of the sheet pan over a tad to get it to fit in there, but it covers pretty much the entire bottom of the cooker.

I had read many comments and posts from owners on the length of burn time, most saying they only get between 4 to 5 hours before having to reload charcoal. So I did some testing after my modifications, and found that I was getting 14+ hours of burn time at 250, using B&B Competition briquettes strategically arranged (empty cooker) in the charcoal basket. I did not follow what anyone has shown in videos or what Backwoods suggests in how to start and maintain a fire. I got an air inlet that interfaced to a slip in guru type fan, and installed it over the left back side sliding air inlet of the Backwoods. I then sealed the right front sliding air inlet, so the only air going into the fire chamber was via the fan. I hand arranged the B&B in the basket and left an empty space for about 10 briquettes, which I lit with a chimney, and dumped into the empty spot in the front right corner of the charcoal basket, the furthest spot away from the left rear air inlet. The burn was good and long, but I didn't like the way the charcoal burned across the entire basket, so I made a divider for the charcoal box that sits in the center (long ways) and makes a U pattern. The burn time (empty cooker) using this divider, and the strategically placed charcoal, went to 20+ hours at 250, so much for the 4 to 5 hour burn time rumors.

My current controller is an original Fireboard with Drive cable, and with that, I needed a fan. I had a fireboard fan, but there isn't a guru slip in adapter for it, so like everyone else I bought a BBQ Guru fan, the PitBull. Since the fan is a high CFM fan, I set the max fan output to 50% in the Fireboard Drive settings. With this setup I had issues with temp spikes, irregularities in temp and high temps that just didn't seem to come back in line. So I asked BBQ Guru if their fans were variable speed and compatible with the Fireboard fan that I have and used many times in the past. I was told that the BBQ Guru fans are NOT variable speed, just on and off, but may vary some with the voltage output from the Fireboard. So I decided to test the fan operation, and found that yes, the Guru fan work with the Fireboard, kind of. I changed the Fireboard Drive max fan output to 100%, used manual mode to test the fan, and found that the Guru fan didn't even run at <30% fan speed, pulsed and stuttered between 30% to about 40% fan speed, and seemed to run OK above 40% fan speed. Then I changed the max fan output in the Fireboard Drive settings and found that this just seemed to compound the issue. OK, time for a different fan, so I cobbled together a way to attach the Fireboard fan, with ball valve adapter I had, and did the tests again, and found that the Fireboard worked perfectly from 1% to 100% fan speed, no matter what value I set the max fan speed to in the Fireboard Drive settings. This is the setup I used in getting 14+ and 20+ hours burn time, with negligible temp spikes and almost a perfect flat line chart(s). Hint: cut off all air intake BEFORE opening the cooking chamber door, and open it back up, AFTER closing the door, because not doing this causes large temp spikes, as opening the door makes it the exhaust chimney, causing a rush of unmitigated air into the firebox.

OK, since Fireboard doesn't have a Guru adapter for their fan, I looked for a different variable speed fan like the Fireboard fan. I found that Humphreys BBQ has a fan that they call the Fireboard fan, and it has a Guru interface that will slide into the Guru adapter. I contacted them to ask if their fan was variable speed and worked like the Fireboard, and was told yes, so I ordered fans. Received the fan(s), and went through the same tests I had done previously. This fan is absolutely better than the Guru as far as working more like the Fireboard fan, but, the test showed that the fan did not run at all <15% fan speed from the Fireboard. So until I looked at the session graph(s) from the previous test with the Fireboard fan, I was almost convinced this fan was the way to go. But the session graphs showed that after getting up to temp, and into a maintenance mode, the Fireboard was running the fan speed mostly <10% to maintain my set temp, so no go on this fan either since it doesn't even run <15% fan speed. I contacted Fireboard to suggest they make a Fireboard Guru adapter, but that doesn't help me immediate need. I remembered seeing something called a HFB adapter on the Humphreys website, which is used to convert a Fireboard fan to work with the Guru slide in air inlet. So in looking at the Humphreys fan, and comparing it to the Fireboard fan. I removed the existing fan from the Humphreys fan, removed the existing fan from the Fireboard fan, and compared them. The Fireboard fan is a dimensional match, so I installed the Fireboard fan into the Humphreys fan assembly, and tossed the Humphreys fan. Now I have a fan that is 100% Fireboard compatible, with a Guru interface that works perfectly from 1% to 100% fan speed, no matter what the max fan output is set to in the Drive settings. Hint: this new fan setup requires a ball valve between the fan and the firebox, as the Humphreys fan, and the HFB kit, do not have a damper built in like the Guru and Fireboard fans do.

If you have read this far, thank you. I hope this helps someone else save their time, money and temperature management hair pulling/frustrations. My bet is that if you are having temperature management issues with using a Fireboard Drive, and not using a Fireboard fan, the issue is probably the fan you are using. Now if I could only recoup the money I spent on all the fans, etc.....

 

[G'Pa]

Here is a 10 1/2 hour session chart. The control channel is #1, and the blue line is the set temp.

Going left to right, the set temp is 250, the first dip was when meat was loaded, then the set temp was bumped to 275, second dip was when meat came off, then bumped the set temp to 300, and last dip was when the rest of the meat came off.

The nearly flat line on the set temp is a direct result of using the FIreboard fan, per my OP. The green on the image is the fan speed percentage, and per my OP, if using a Guru fan, nothing below the purple line would have triggered the fan to run, and if using the Humphreys fan, nothing below the yellow line would have triggered the fan to run. Using the Fireboard fan allowed the set temperature in the cooker to be properly managed, without huge temp spikes and dips, resulting in the nearly flat line of the cooker temperature.

 

[G'Pa]

Here are some pictures of the G2 Chubby mods I did to eliminate having to use water in the water pan.

I put 3 inches of ceramic insulation, wrapped in 2 layers of heavy duty aluminum foil, into the water pan.


I put a 3/16 inch plate sized to the interior dimensions of the bottom of the cooker to cover the water pan and insulation.


I found a stainless steel pan that I modified to fit into the cooker above the 3/16 inch plate, to be the drip pan. I wrap it in foil when cooking.


The bottom grate fits perfectly over the drip pan.


Here is a view of the 4 racks with the modifications to eliminate the use of water in the cooker.

 

[G'Pa]

Here is a current Fireboard setup I added to the modified G2 Chubby. I will replace the original Fireboard with a Fireboard 2 when it arrives. The fan adapter plate is from Humphreys, the piping is stainless steel that I put together. The fan is the HFB mount from Humphreys with a Fireboard fan installed in it, to take true advantage of the Fireboard's ability to interface with a real variable speed fan per my original post. I found the magnets to hold the probe leads on Amazon.

 

[G'Pa]

This was the first test burn with a full load of charcoal after my modifications. I placed the charcoal to maximize the available space in the charcoal basket, as the space available is very limited in this older G2 Chubby, and I wanted to get the longest burn possible after reading other people's posts about only getting 5 to 6 hours out of a full load of charcoal. The charcoal is B&B Competition in the orange bag. This picture was after 5 hours.

I did not like the way the charcoal burned, so I decided to make a divider for the charcoal basket. This allowed me to somewhat direct the burn of the charcoal to maximize the burn and burn time. The wood chunks are small, but I found that this is all that is needed for me to get the results I want.


This is a picture of the burn results with the divider. This was after 16 hours. I didn't like the way the charcoal burn in the corners, so I opened up the end of the basket by putting in some 1 inch holes in the corners, which in subsequent burn test almost eliminated the problem with the corners. I have also stopped putting any charcoal next to the divider to prevent the premature burn from side to side. In hindsight, I guess I could have just lined up the charcoal in 2 rows around the perimeter of the charcoal basket.


I really didn't like that the ash pan was just sitting separately in under the charcoal basket on the bottom of the firebox, and the annoyance of not having handles on the charcoal basket and the ash pan, so I modified things to attach the ash pan to the bottom of the charcoal basket to make it one integrated piece, and I added handles to each to make them easier to work with.


Here is the charcoal I use.

 

[G'Pa]

I decided I didn't like having an ambient probe to deal with inside the cooker, attached to a shelf, as it always seemed to get in the way of loading/unloading meat and pulling the shelves in and out. So I purchased a 1/2" NPT probe from Fireboard, removed the analog door gauge, and replaced it with the new Fireboard probe. The fireboard probe is shorter than the door gauge I removed by approximately 1 1/4 inches. Because of this, I found during testing that I needed to add a 25 degree offset to the new probe to bring it in line with the temperatures from the center of each of the 4 shelves.

Here is the new Fireboard probe installed in the door.


Here is how I gathered the temperatures from each shelf during testing. Notice the probe of the new Fireboard door probe. I would have liked it to be an inch or so longer, but Fireboard does not have one available.


So with all of the testing and modifications, I decided to do a final test to see how everything worked. To recap, I did modifications to remove the need to use water in the cooker, sealed the front right air intake and modified the left rear air intake to utilize a Fireboard controller and a guru adapted modified Fireboard fan, changed the charcoal basket and ash pan configuration, and replaced the door gauge with an ambient probe.

For this test I used 24 B&B charcoal briquettes configured as this photo shows.


I used a small Weber chimney to light about 10 B&B briquettes (some of it was recovered charcoal from previous burns, new broken pieces from the bag along with a few whole briquettes) to get the fire started by dumping them in the empty space in front of the staged charcoal.


Here is the Fireboard graph of this test, showing the results of all of the modifications. The set temp was 250, This screen shot was after the test was done and the temps dropped off showing the charcoal was used up, which is why the temps the probes are showing are all below the set temp, and the fan percentage spiked. The cooker was empty, and the door(s) were never opened. Notice the duration of the test, 11 hours and 35 minutes, with only the load of charcoal shown above. Also notice the green portion of the graph, as this is the fan speed in percentage. Going back to my original post, you can see that using anything but a Fireboard fan, with the Fireboard Drive, would never provide this type of result.


Here is a picture of the charcoal burn after the test. The reclaimed charcoal doesn't burn as well, but it works great in a chimney to start the fire. The 24 original briquettes I staged are gone. It's mazing that my modifications, using only 24 briquettes, lasted for over 11 hours. I'm calling it a win! Now if my new Cascade Smoker would get here.....

 

[ModelMaker]

Man, you need to find something to do with your time!
Oh, and welcome.
Ed

 

[G'Pa]

Man, you need to find something to do with your time!
Oh, and welcome.
Ed

Thanks Ed. Time is a relative term when you are retired.