Design - How soon can the underfloor heating be turned on?

The limecrete builds strength slower than concrete and therefore requires longer before the underfloor heating can be commissioned. We recommend at least 2-3 months of drying before the underfloor heating is turned on, this allows the limecrete set, carbonate and release the majority of the moisture from installation before it is stressed.

There are risks to turning the underfloor heating on too early, similar to if the building is too hot during the initial curing process, turning the underfloor heating on too quickly will result in force drying causing shrinkage and cracking to occur. When the water molecules evaporate they leave small voids behind in the limecrete, if this happens before the limecrete has built its strength then cracks can occur throughout the slab.

When the underfloor heating is commissioned, the heat must be increased gradually so as to not thermally shock the limecrete. The manifold will have a flow temperature control for each loop (independent of the thermostat temperature) which adjusts the temperature of the water flowing through the pipes via a mixing valve, this must be turned down to the minimum temperature (normally around 30-35 degrees). The thermostat should also be set a few degrees above ambient the current ambient temperature with the aim that when the heating does come on it gently heats up the slab. After the system has been on for a couple of days the flow temperature (on the manifold) can be increased one degree per day until it is at normal operating temperature.