I also have gas in connection with underfloor heating, water-based towel dryers, and water-based pre- and post-heaters for the centralized controlled residential ventilation. With the boiler, I heat the water to 45 degrees, which goes to a hydraulic separator. From there, three branches go out: one each to the underfloor heating, towel dryer, and controlled residential ventilation (water coil). In the underfloor heating, I have installed a pre-control that regulates the flow temperature between 27 and 35 degrees depending on the outside temperature.
The heating coils of the controlled residential ventilation also each have a pre-control (pre- and post-heater) and are designed so that the pre-heater, at 45 degrees flow temperature, manages to warm -25 degrees cold air (for a maximum of about 500m³/h) up to 10 degrees. The post-heater from 10 degrees to 25 degrees (in between is the heat recovery, so the post-heater is very generously sized).
The towel dryer has no pre-control (why should it) and receives the full 45 degrees.
Just a rough overview