Ah ok. Temperature outisde: 6C. Temperature throughout the house interior: 22C. Even in all the numbered locations I indicated.   Yeah, I did this at the very start of noticing the issue, and the sinks at locations 1 & 3 (from my screenshots) don't plumb to the rain barrels no matter where they're positioned.    

Version:[42.7.0] [rev:28118] Mode: [Singleplayer] Server settings: [N/A] Mods: [None] Save: [New Save] Reproduction steps: dismantle hammers and etc. do not give handle back, this is not intuitive despite new tools/weapons crafting and health  system, where it become modular. example: i have bad handle on one tool and good head on another- wanna combine best of the best, but handle just disappear from craft results. so i cant see dismantle options for short weapons.   (also i have the feeling, that using tool as weapon damaging the head and handle the equivalent so it becoming pointless to craft and change handle.)     (no logs files this time because I'm too frustrated to again abort my current game and going in clear save to enable debug and check it all for u guys..

You go outside, check the temperature, you go inside, check the temperature. If they are different, then the indoor room is properly recognized. Have you also tried moving the sinks around? Removing it and placing it back as an example.

Yes, they contain water from the rain, but room 2 is the only sink that has a plumbable sink to the rain barrels positioned above. And I've tried multiple positions for the sinks and rain barrels above to test whether it's a positioning issues, or a rain barrel type issue. No change to room 2 being the only room that can plumb to barrels once they have rain water.   I've not entirely sure how to check while in debug mode, since I've never explored that side of things. Any quick steps on how to do this?      

[42.7.0] [rev:28118] still actual, devs! (author, update ur title)