Pencil anode size - is bigger better?

[JoeRobertJr]

I am replacing the anodes in my 2" diameter Sen-Dure heat exchanger for the first time. The previous owner left an assortment of replacements as pictured. What came out was a 1/4" diameter with an adapter for the threads, but the exchanger could accept a 3/8" diameter anode. That is, either of the two options in the picture to the right will fit. My gut tells me that the thicker anode would last longer, and that is one less set of threads to leak. Am I missing an advantage of using the thinner size?

[ItDepends]

You are missing nothing. Just a heads up for your first rodeo... sometimes you have to cut these shorter.

[Putt-Putt]

While I agree that the larger diameter anode will likely last longer, one thing to consider is that these are likely pipe threads (NPT) and by design seal by way of thread profile deformation. Tape or dope does not stop this deformation from occurring. This means that each time you replace the anode you render the threads in the fitting on the cooler, one step closer to not being able to make the next seal, or in other words simply more worn out.

Using the adapter (usually called a bushing) and leaving it firmly installed in the cooler when you re & re anodes puts the wear on the bushing, not the cooler's fitting.

Replacing the bushing after say 20 anode replacements restores the threads.

I've replaced more than one perfectly good cooler simply due to the PO or others repeatedly over tightening these pipe threads, wearing out the cooler's threads.

Perhaps that has already almost happened and the PO installed the bushing to restore the threads.

[Adelie]

Look for a manual onboard or Google it for the heat exchanger and see what it recommends.

[JoeRobertJr]

Thanks, ItDepends, for the heads up on possibly needing to trim the end. It does seem like the anode is long enough to touch the other side .

Thanks, Putt-Putt, for the caution about the wear on the exchanger body threads. That makes sense as an advantage of using the thinner anode + bushing.

Adelie, thanks. I turned to this forum only after searching my manuals and online, but finding nothing conclusive.