This depends on the ambient temperature and the levels of insulation of your building. Herschel Far Infrared heaters work by warming up the thermal mass of the room and on initial start up, this may take several hours and in some cases days, depending on the area to be heated (a damp basement room for example). It is very important to go through this phase to warm the thermal mass of the room for the heaters to work efficiently – cold walls and floors will not give occupants a feeling of warmth and wellbeing. For the system to work effectively all surfaces in the room should be at the same comfortable temperature and will start radiating back.
We recommend leaving the heaters on constantly until the room reaches the desired temperature. They then work most effectively by “topping up” the temperature using a thermostat control, being operated on a timer or a combination of both.