Another idea:
The Wiser output feed would normally drive a motorised valve. (I don't know if these are common in Romania), but they have a small motor that turns a valve and when it reaches a certain position, a microswitch is activated. That microswitch is normally used to send power to the boiler / pump, rather than the Wiser itself.
You can buy replacement actuators for these valves (containing just the motor and switch(es). There are lots of different brands, but this
Honeywell version was one of the cheaper ones I found. There is a datasheet (for the entire valve)
HERE. (You wouldn't need the actual valve part).
Electrically it's inferior to the other relays I linked to (too many moving parts!), but at least it's the sort of thing you might expect to find connected to a boiler