It wasn’t that long ago that heaters were single phase models.
The boiler was only able to operate at maximum capacity.
The heater would kick in and blast at full speed until reaching the temperature setting on the temperature control. At that point, the heater would shut down completely. The repetitive on and off cycling caused indoor temperature changes, wear and tear on components and excessive energy consumption. Eventually, the industry developed multi-phase heaters. These boilers were able to operate at low and high speed. This improvement helped to maintain a more consistent temperature and increase energy efficiency. Today, there are heaters featuring flexible-speed technology. The smart technology enables the heater to automatically adjust output to match the exact requirements of the home. The advanced engineering provides adjustments in tiny one percent increments someplace between forty and one hundred percent capacity, but very rarely does the heater need to operate at full capacity. Other than starting up the heater for the first time when the outdoor abruptly drops, it can operate at a lower capacity. Running more often at lower speeds, the heater uses less energy and deals with less strain. It doesn’t cause as many complications with overly dry air. Modern heaters offer the added benefits of wireless technology. With the addition of a smart temperature control, the system can be adjusted remotely from a PC, tablet or smartphone. An independent temperature control in each room provides for zone control. Targeting individual rooms significantly increases energy saving potential, trims running costs and improves comfort. There is less impact on the environment.