Does anyone know what size the brass drain plug is on the JH tank? I just purchased an aluminum tank and would like to find an aluminum plug but I haven't been able to determine the size of the original (thread count, etc). It doesn't seem to fit into any of the usual sizes. Delta just carries the replacement and they don't know the dimensions. Fastenal couldn't figure it out either. I might just go ahead and use the brass but I don't want to set up a situation where I'd be inviting corrosion. Any thoughts?
Looks like I should have started at my local hardware store. While it looks like 5/8" it's a exact match to 3/8" NPT. They matched it up right away. As far as corrosion goes with the brass plug/aluminum tank, I'm hearing and reading differing opinions. Some say always keep aluminum with aluminum, others say stainless, and some say it really doesn't matter because if I use the brass plug there won't be enough corrosion to make a difference in my lifetime. I'm going too play it safe and go with aluminum.