Greetings! I'm looking for recommendations for a small-ish buffer tank for a closed residential radiant heating system. I *think* that I'd prefer stainless steel, but I'm not wedded to that. I would be somehwat open to using tanks that would need to be "repurposed" for this application, if that makes sense, though it seems that small, 30 gallon buffer tanks are not terribly expensive. Any suggestions or specific recommendations would be appreciated. Thanks, Jeff

I'd say just get what you can afford. You can use ANY hot water tank. You don't have to heat water with it. We use a 50 gallon electric hot water tank as our buffer tank. It has no electrical connection. I think it was around $300. The stainless tanks will surely last longer. I can't seem to find it, but I've seen mention of plastic hot water tanks on this forum. They are guaranteed for life.

Home not so cheapo has a 40 gallon tank on their website for $248.

Hope this helps.

Good luck,
Ed

There's little to no advantage to using stainless vs. carbon steels in closed system buffer tanks if used with oxygen barrier tubing & pressurized to at least 12PSI, in which case corrosion is limited. (Cast iron boilers and standard steel buffers should last several decades under these conditions.)

Purpose-built buffers like the Boiler Buddy or Ergamax BTxx line have features that repurposed HW tanks do not, can handle much higher flows, and are designed to work well as hydraulic separators, etc. But if you don't need bigger than a 3/4" connection and have modest flows bottom-of-the-line electric HW heaters can usually fill the bill.