Which heat source is not suitable for use with direct pipe radiant floor heating?

In a direct pipe radiant floor heating system, the heat source should provide a steady, controllable flow of warm water throughout the system. A condensing boiler is designed to maximize energy efficiency by recovering heat from the exhaust gases, which allows it to operate at lower temperatures. While this can be effective in many applications, radiant floor heating typically requires a higher supply temperature to effectively radiate heat through the floor.

The other heat sources, such as electric boilers, steam boilers, and hot water boilers, can typically provide the necessary temperature stability and output needed for effective heating in a direct pipe radiant floor system. Electric boilers deliver consistent hot water, steam boilers can provide high-temperature steam that can be converted, and hot water boilers can operate at higher temperatures to accommodate the needs of radiant heating systems. This makes the condensing boiler less suitable compared to the other options for direct pipe radiant floor heating applications.