Quote Originally Posted by 2000GTP View Post
Aluminized steel is steel that has been hot-dip coated both sides with aluminum-silicon alloy. This process assures a tight metallurgical bond between the steel sheet and its aluminum coating, producing a material with a unique combination of properties possessed neither by steel nor by aluminum alone. Aluminized steel shows a better behavior against corrosion and keeps the properties of the base material steel for temperature lower than 800 °C. For example, it is commonly used for heat exchangers in residential furnaces, mufflers, ovens, ranges, water heaters, fireplaces, bar-b-que burners, and baking pans.
That looks like it came from wikipedia, I did look it up later.
I guess but that long seam that runs under the temp sensor made it look like EMT to me but I looked at the pic again and it does aluminum-ish