When it comes to the different systems in out house, I really have no idea. I don't know the difference between tankless water heaters and water heaters with tanks. I wouldn't know the first thing to do if something broke. I'm just glad when there is hot water for a shower or bath or for doing dishes. I'm also just glad when the heating system works for the house. We are crossing our fingers that nothing breaks right now because if the house got cold, we may just end up getting even sicker.