Refit: water tank anodes

Magnesium water tank anodes.

 While not supplied as standard equipment, magnesium anodes are typically installed to prevent corrosion inside the OVNI’s aluminum water tanks.   Owners tackle this in a variety of ways.  

A google search quickly identified that these anodes are commonly used in North American water heaters, and are often sold as “3/4” magnesium anodes”.   Typically, they are supplied with a 3/4”NPT fitting in one end, and can be easily replaced from the outside of the tank.  I figured I’d make some kind of threaded boss, tap it accordingly, then install it somehow inside the tank, near the bottom, as some others have.  

At some point it occurred to me that an electrical part known as a hub might be a simple and professional-looking way to provide a threaded boss for the anode.  Hubs are used in a variety of applications and are made in a variety of materials.  The part I chose is a made of copper-free aluminum and is marketed by Crouse Hinds.  3/4” NPT thread, part number STA-2.

https://www.eaton.com/us/en-us/skuPage.STA%202.html

I wasted some time and money before I came to the rather obvious conclusion  that it would be easiest to mount the hubs on top of the tank and make up rods that extend to the tank’s bottom.  I wasted more  time and money learning that some 3/4” anodes are actually larger than 3/4” diameter,  and some are smaller, and that some hubs are large enough to accommodate this and some aren't.   

The larger RV model from Amazon, (left, 21mm dia) was slightly too large to fit through the Myers hub. The smaller diameter (18mm/ .700”) anode is pictured above to the left, and below with the hub comfortably installed. 

The anode I chose is the Rheem Protech SP11309Y, $12 CDN for a 34” anode.   This is cut to fit the tank which is approximately 18.5" deep.   

https://www.homedepot.ca/product/rheem-magnesium-anode-rod/1001514997

I used a hole saw as pictured and punched through the top of the tank with ease.