Man inspecting Tankless Hyrdronic heater

When Steve McCoy’s furnace reached the end of its life, he didn’t want to simply update it with a new one. Instead, McCoy wanted to make his home a showcase for a rapidly advancing technology: hydronic forced-air heating powered by a propane tankless water heater.

As vice president of business development for propane provider Blossman Gas, McCoy sees this technology as not only a milestone for the propane industry but also a major opportunity for construction pros to improve comfort, efficiency, and space savings in new construction and retrofit scenarios.

“What inspires me about the technology first and foremost is the comfort,” McCoy says. “In the gas industry, as we're competing against electric for market share, we highlight the comfort that gas provides versus electric and, more specifically, comfort as it relates to register temperature.”

Whereas heat pumps deliver register temperatures that can feel cool at around 95 degrees Fahrenheit, below the human body temperature, gas furnaces deliver heated air at around 140 degrees. And air handlers with a hydronic heating loop can reach a cozy level of about 130 degrees. In the videos on this page, McCoy and Blossman Gas regional service pack specialist Damian Kelley provide an overview of how this innovative technology works and how builders and contractors can optimize their installation.

How to heat with tankless

Hydronic air handlers, sometimes referred to as water furnaces, provide space heating by using a hydronic heating loop to heat air as the blower moves it into the home. Tankless water heater manufacturers such as Rinnai have recently launched air-handling units and controls designed specifically to work with tankless units, which overcome some design challenges and provide several advantages. Tankless water heaters designed to work with a paired system such as Rinnai’s offer reliability and thermal efficiency, with condensing units achieving efficiency levels up to 94 percent. And because they heat water continuously on demand, there’s no need to worry about running out of domestic hot water.

In furnace replacement scenarios such as McCoy’s, installing the tankless unit can be extremely straightforward because the furnace’s gas line and ventilation can be reused. “For an installer of the system, it could save up to 2–3 hours of time installing it by not having to do your venting or additional gas lines,” says Kelley, who performed McCoy’s installation.

The tankless water heater also allows for a very compact installation, creating space savings by eliminating the need for a separate electric or gas storage tank water heater. “Approximately 200 cubic feet of space was saved in my situation,” McCoy says. “So that same 200 cubic feet could be used in new construction to add a closet or simply reduce the size of the structure. With building material prices escalating like they are, it could save some money in new construction.”

The hydronic heating system can also provide energy cost savings by eliminating the use of emergency electric heat strips when the temperatures dip. Check out the full video to learn more, or visit for additional tips on optimizing your installation.