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BuffMax – The Secret to High-Efficiency Hydronics

Today is all about steady state efficiency in hydronic systems but before we get to that we need a quick history lesson. Before the turn of the century, hydronic systems were BIG. You’d have a large cast-iron boiler paired with large pumps and large piping providing a high volume of hot water to large radiators. This provided reliable heat with minimum stress on the equipment.

Modern hydronics are different. The standard piping is now 1-1/4” copper, condensing boilers are suitcase-sized and light enough to be wall-mounted, and free-standing radiators have been supplanted by baseboards and slim panels which are themselves segmented into small zones.

All of this is in service of the (important and necessary) goal of increasing efficiency. Unfortunately, there is a gap between AFUE, the standard measurement of efficiency, and the real world. While a unit might say ‘95%’ on the label it probably isn’t reaching that efficiency consistently if ever.


Short cycling. The reduced volume of modern systems means a boiler can satisfy a heating call in a shorter amount of time. Unfortunately, hydronic equipment needs time to ramp up to steady state (peak) efficiency. If a system is only activating for five minutes at a time, it will never reach that point. When your system is segmented into zones, that makes it even more complicated; it’s not uncommon to see sub-8,000 BTU zones with a boiler than can only modulate down to 15,000 BTU.

So, what can we do if we want efficient hydronic heat in reasonably sized residential zones? We can BuffMax it! BuffMax is technically a buffer tank but that is underselling it. In truth, BuffMax is a 3-in-1 hybrid hydronic solution.

Buffer Tank + Storage Tank + Hydraulic Separator

So, the issue is that modern boilers are constantly turning on and off the provide heating to small zones. This creates wear-and-tear on the equipment, it wastes the excess energy when a zone is smaller than a boiler’s minimum input capacity, and it prevents the system from functioning at peak efficiency.

To solve that, the BuffMax tank as a middleman. Instead of a few gallons of water being heated and sent through the zone, the BuffMax will fill itself completely (30 gallons or 50 gallons) then store that heated water until it is needed. Because the BuffMax has a high volume, the system will hit steady state efficiency and then the BuffMax can satisfy multiple calls for heat before it needs to be refilled, preventing short cycling.

The BuffMax also serves as a full hydraulic separator. This means that it will be venting air bubbles and eliminating impurities in the system in addition to functioning as a buffer and storage tank. This protects pumps and enhances the lifespan of all components in the system.

Bottom Line

High-efficiency hydronics and zoned heating are both exceptional advancements but when combined they frequently result in suboptimal performance. Luckily, that can be solved simply and with a single product. BuffMax tanks are available now at all Able branches as well online.

Shop BuffMax Tanks Online

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