Tennat leave the door open and I smell weed/marijuana.Marijuana

[Aria Saha]

Someone please help me, as I am worried if my furnace will cost me lot to fix. I always have to go from the same route so I always see my rental house and every time I pass, I see the door left open. I am not sure what steps I can take as they leaves the door open even in -2 degree. It was odd! The other day I had to pick up something so I went to check on them, the house was kept well inside but I smell so much marijuana/weed, I had said no smoking of any substance The house so hot inside as if the house was on fire. I didn't wanted to make it weird, or make them think like I moniter them all the time. I just ask her if the furnace was working and she said its working but get hot sometime when they close the door but she went on and said I will let's you know if any thing happens. I could see thermos set to almost 90 Smith. I couldn't say anything but I am so much worried. Tennat pays for electric and gas but I am worried that it will cost me lot to fix if it gets broken. 😭 please help me what should I do? Also those Tennat are very nice, I have never had issue. They been paying rent on time.