I've seen in all the posts that the "heat for 10 sec" issue has been reported multiple times.
But this problem persists in the latest version 0.4.11
As it cost me a contactor, I searched a bit to find where this error came from.

I changed this line (lin 367) in the program:

if power == 0:

by ...

Look at this:
https://github.com/syrhus/domoticz-weekly-planning