900 Watt upgrade burning insulation

[bedfordbruisers]

 So I upgraded my heating element to the 900 W and once I plugged it in it started getting up to temperature much faster than the original element, as expected. However as it ran for about 10 minutes it got up to 200° and I started smelling a terrible smell and there was smoke coming from the seams of the back panel. I opened  The back of the smoker up after cutting the power and it appears that the heating element was getting so hot it was burning through the insulation. The foam on the back panel was charred black near the heating element and the wire protectors were burnt. I took the wires out of the fire sleeves and they appeared to be in perfect condition.  I did this because my original thought was that the wires were burning up, but that was not the case. I mounted the heating element with 2 inch bolts but the only thing I can think of is to use 4 inch bolts to mount the heating element further away from the back of the smoker. This has been a huge headache for me , If anyone can help me or has had any similar experience please send me a text message at 540–597–9519 due to me not checking the forum often enough. Thank you

[Edward176]

Have a look at this YouTube Video, it may help.
https://www.youtube.com/watch?v=uy_wLkpDj9I

[Elfremi]

Hey Bedfordbruisers,

I had some concerns when I modded my smoker to 900W. The first cook saw some discoloration of the insulation, but no melting like in your mod. I also originally mounted the new heating element with 2" bolts, but I switched them for 2.5" bolts after that first cook. I just didn't feel comfortable with the lack of space between the element and the wall. I also added some extra protection after my first cook, as you can see in this pic:



I just wanted a little bit of extra peace of mind when I used my smoker. I purchased the heat shield on Amazon:

Canadian Link
https://www.amazon.ca/gp/product/B002UPL61U/ref=ppx_yo_dt_b_asin_title_o04_s00?ie=UTF8&th=1

American Link
https://www.amazon.com/Heatshield-Products-110614-Inferno-Aluminum/dp/B002UPL61U/ref=sr_1_1?keywords=Heatshield+Products+110614+Inferno+6-Inch+X+14-Inch+Aluminum+Heat+Shield&qid=1569020618&s=gateway&sr=8-1

It's ceramic insulation wrapped in aluminum. You can trim it to fit by opening up the aluminum wrap, trimming the ceramic insulation, trimming the outer wrap so you don't have any excess, then wrapping the ceramic insulation back up. It's not the cheapest thing, but I figured it was worth the extra expense if it meant a safer setup. 

[bedfordbruisers]

So I put a sheet of galvanized steel as well as a 1/4" steel plate directly behind the element and also replaced the 2 inch bolts with 3.5 inch to mount it further away. When the smoker gets to 225 I can still smell the insulation or foam burning and the back of the smoker is almost hot enough to fry an egg on at the height of the element. The bolts that are mounted through the back to hold the new element on are even hotter. Is this normal?

[Elfremi]

I'm not having the same issues. I also sealed up the holes for the bolts with pure silicone. Did you change the wiring at all? I used the video Edward176 shared as my main guide to doing the mod, but I changed the wiring to 14 gauge. I know you said the wiring didn't look damaged after that first cook, though the shielding was damaged. I'm not an electrician, but the demand on the original wiring would be much greater, causing overheating, damage to the insulation and heat transfer to the back of the cabinet. The wires themselves might not appear damaged. The melting point of copper wire is 1982°F and aluminum wire is 1221°F. The highest melting point for high temp wire insulation that I could find was 482°F for PTFE/glass insulation (see High Temp Wire). I think the original wiring insulation is PTFE/glass, but I could be wrong.

Anyway, with the new heating element, the current is much higher than before. The original heating element was drawing 4.17 amps (500W/120V) while the new element is drawing 7.5 amps (900W/120V). The old 18 gauge wiring can't handle the new current demand, not without overheating at least (see AWG Wire Gauge Current Ratings). I know some people say there's no need to upgrade the wires in the smoker cabinet, but I think it's in your best interest to do so, especially now that the original wire insulation is damaged. You shouldn't run the cabinet without changing the wiring to at least 14 gauge, in my personal opinion.

Maybe someone with more electrical knowledge can chime in and offer some help.

[bedfordbruisers]

I had to splice in some 14 gauge to add length but I didn't completely replace the wire. I used the video to do the upgrade as well. He never shows the back of the smoker in the video. Am I correct with having drilled the holes from the inside all the way to the outside panel. When everything is put together, I have two hex heads exposed on the outside. I guess I'm confused with where you put the silicone.

[Habanero Smoker]

You should not have drilled through the back panel. The bolts are inserted through the insulation and the back wall, not the back panel. The head of the bolt should be resting against the cabinet wall and protruding through the wall into the cabinet.

It looks like your problem is that the heating element is too close to the wall. After installing the bolts correctly you should be good to go. You may want to switch back to 2.5-inch bolts. Use the silicon to patch up the two holes you mistakenly drilled through the back panel.

If you leave the galvanized steel in the cabinet, re-season the cabinet to burn off as much zinc oxide.

[bedfordbruisers]

The fact that I went through to the back wall could be the problem then. If the bolts are heating up so much that they are melting the foam through the shaft of the bolt.

[Elfremi]

Habanero Smoker beat me to it.

Here's the back of my smoker with the panel off. I've circled the two holes you should see. You can't see the silicone in this image because I only thought of covering the holes after I took that pic. 

I'd imagine there was a lot of heat being transferred through those bolts right to the back of the cabinet. I still think you should completely change out the wiring instead of just splicing onto the existing wiring, but that's just me.

[Habanero Smoker]

Looks like you are getting close to resolving the problem. The bolts are transferring a lot of heat to the back panel, but you also have the problem of the foam insulation burning. To solve that you will need to space the element further away from the cabinet wall. Increasing the air space between the element and the cabinet wall will reduce the amount of heat the back cabinet wall will absorbed, thus reducing the radiant heat temperature of the back cabinet wall. That should stop the burning smell you are getting.

[bedfordbruisers]

I am hopeful that mounting the bolts inside of the back panel and adding the silicon will fix my issue. The bolts I used were 3.5" and I also have a sheet of galvanized metal as well as a 1/4 inch piece of steel that I have hardened to use as a heat shield. If this doesn't work I am out of ideas. I will post pictures of what my problem looked like, as well as how I have the element mounted. Also, for those of you that changed all the wires, did you replace the fuse? If so, does the smoker require a different size fuse with the 14 gauge wire?

[Elfremi]

I kept the fuse that came with the cabinet. The wire gauge shouldn't have an effect on the operation of the fuse. 

[bedfordbruisers]

Update:

The fact that I drilled holes all the way through the back back panel to mount the new element was the issue. I have since mounted the bolts inside the back panel against the back of the smoker cabinet and filled the holes behind the bolts with high temp silicon. Smoker works better than ever, especially with the Auber 1200 WSD PID. I can't believe I ever tried to smoke anything without a PID. The last time I did a pork butt, I was up every hour of the night trying to get the temperature within a reasonable range. Now I can truly set it and forget it. I can have the smoker turn down to 140 F after the pork butt hits the magic number so I don't have to be there at the exact moment. I will be getting a lot more use out of this smoker now.

[Habanero Smoker]

Thanks for the update. Glad you got everything up and running.