A gravity-fed heating system uses the force of gravity to circulate water in the heating system.
Typically, such a heating system has a cold water tank in the loft or attic of the house, a boiler on the ground floor and a hot water cylinder somewhere between these two.
When there is a call for hot water, the boiler fires up and heats up a large volume of water. As cold water is denser than the newly heated water, it falls down to the boiler. The hot water moves up to the hot water cylinder from where it gets forced out to the hot water taps.
If there is a heat request during this time, a pump circulates the heated water through the radiators. So, in a gravity-fed heating system, it is not possible to have heating without hot water. Such systems are usually controlled by programmers that automatically switch hot water on whenever there is a call for heat.
Does tado° support gravity-fed heating systems?