Pecan said "So I had a hot water tank installed by Mr. Rooter in June 2017! I see they are no longer! I have a 6year warranty on the tank and another 3 years for parts! Anyone know if my warranty would be void now? Or would someone else grant it if needed? "
The warranty is covered by the tank manufacturer. For example Rheem, Bradford White etc. Any plumbing/mechanical company will be able to use the tag from your current water heater to get you warrant if you have an issue with it.