Motoric valve drives for floor heating


I am looking into ways to automate my warm water under floor heating system.

I would prefer to find a cheap solution that relies on Xiaomi temperature sensors talking to Home Assistant and some cheap electrical boards with relays to control actuators on the manifold. The problem I see in that solution though is that the actuators are either fully open or fully closed. That means the temperature will rock up and down around the desired temperature as the valves open and close.

I know there are more advanced (and expensive) options like Homematic IP motorised floor heating actuator and valve drives that can control the flow better and hold it more steady and can even connect to HA. But as I am building a two floor house I will need two manifolds and thus two sets of those products so due to the higher price I am looking for alternative solution.

Is there any way to get similar function with a DIY solution and some valve drives that are not just open or closed but rather can open partially like the Homematic IP solution?