Commercial Unit question

[Rob Yuen]

We recently took over a commercial unit that had poorly written terms by the previous landlord. The intent is to have a NNN type lease. They're up for renewal in a few months so I want to spell everything in the future but I have a few ques hoping to get some advice right now:

1. 1. The water heater that provides hot water to that unit recently broke down which we repaired. We billed the tenant (its a small gift shop so they're not professional commercial folks). They said that its not their responsibility and that its located external/outside from the unit not internal. Additionally, they did not buy that water heater so how do they know if its in poor condition or not. They said its the landlord's responsibility.
2. 2. We have property insurance for the overall building and I believe it is standard practice that commercial tenants pay for their own property insurance for inside their walls (just like you would have renters insurance in a residential unit). They said they don't have it and its the landlord's responsibility.

What is the general rule of thumb or best practices for these two scenarios? I feel these two items should be tenant responsibility. Is there a resource or website I can point them to to show this is general practice?