Does Cozy Heat require a heatsink?

Yes for floor and space heating — the cable must be embedded in a cementitious material such as mortar, standard concrete, or lightweight concrete. The cementitious heatsink is essential for even heat distribution across the floor surface above; without it, heat concentrates at the cable rather than spreading across the floor. For slab heating and heat loss prevention, the cable is adhered directly to the underside of the concrete slab — the slab itself acts as the thermal mass, and no separate heatsink embed is required.