What additional feature must be provided with radiant floor heating systems along with insulation?

In radiant floor heating systems, providing a thermal break along with insulation is essential for optimizing energy efficiency and system performance. A thermal break serves to minimize heat loss to the ground, which is crucial in maintaining the desired temperature for the heated space above. Without this feature, the heat generated by the system could dissipate downwards into the ground, leading to increased energy consumption and reduced effectiveness of the heating system.

Insulation alone is not enough in a radiant floor heating setup. While it helps keep the heat within the living space, the thermal break specifically addresses the need to separate the heated floor from cooler surfaces, preventing thermal bridging and enhancing overall system efficiency. This is particularly important in installations over concrete slabs, where heat can easily escape.

The other choices, while possibly relevant in different contexts or systems, do not directly contribute to the effective operation of a radiant floor heating system alongside insulation. A pressure relief valve is related to plumbing systems and is not applicable here, a manual thermostat is important for regulating temperature but does not impact insulation effectiveness, and a moisture barrier, although beneficial in controlling humidity, does not directly address the energy efficiency aspect tied to thermal breaks in heating systems.