Choosing between a condensing and non-condensing boiler for commercial applications might seem like a fairly straightforward ROI calculation: Is the energy savings from the more efficient condensing boiler worth the higher upfront cost?

But in HPAC Engineering, Weil-McLain senior product manager John Miller argues that using both in a hybrid system can help ensure your building is always running at optimum efficiency. Non-condensing boilers, he explains, have efficiencies ranging from 80 to 85 percent and are designed to run at higher return water temperatures above 130 degrees Fahrenheit to maximize longevity. These applications typically occur in the core heating months, December–February.

“Condensing boilers reach their maximum efficiency (upwards of 95 percent) when the return water temperature is below dew point and are more aligned with the milder heating season shoulder months of October, November, March and April,” Miller writes. “Running condensing boilers in high return temperature applications reduces their operating efficiency to marginally higher than non-condensing boiler designs.”

So, with condensing boilers having a higher upfront cost than non-condensing systems — upward of 30–40 percent more, Miller writes — engineers or building owners could take the incremental step of upgrading one of their boilers to a higher-efficiency condensing unit while still lowering operating costs and creating comfortable, consistent building temperatures. Is going hybrid an option that makes sense for your commercial building?

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