If more insulation is installed under the radiant heating, do I need less radiant tubing?
The more foam insulation board or other moisture-resistant insulation material under a concrete floor slab, the more efficient the building becomes. This is no different with a hydronic heating system. The more rigid moisture-resistant the insulation, the more efficient the heating system becomes; however, this does not necessarily mean you need less radiant heat tubing. The system needs to be engineered and, in order to ensure the heat dissipates evenly, a certain amount of radiant heat tubing is required.
Size of tubing is also important when calculating the length of radiant heat tubing required. A ½ inch tube cannot supply the same volume of heat as a ¾ inch tube; therefore, it is always important to make sure the hydronic or electric radiant floor heating system is properly engineered, insulated, and installed.