ᐅ Is a double flue chimney necessary?

Hello dear forum members,

We are currently planning to build a single-family house. We have two questions that are not entirely clear to us.

1) We want to heat our single-family house as follows: primarily with gas, domestic hot water with solar panels on the roof (if possible and feasible also for supporting the heating water), and additionally a wood-burning stove with water jacket.
-> Now the question: Do we need a two-flue chimney for this?

2) It is planned to have underfloor heating on the ground floor and upper floor. Only in the bathrooms (ground floor and upper floor) there will be a radiator each to quickly get a warm bathroom.
-> Can the two radiators be operated with the same heating circuit, or is a higher supply temperature required here?

Thank you very much for your answers.

Best regards,
Härtsfelder

2) I plan to do that as well.
The additional radiators need to operate with a higher flow temperature. The underfloor heating can manage with a lower flow temperature due to its large surface area.
The domestic hot water has a higher temperature anyway. That should work.
I will have the details explained to me by a builder next week.