I'm a landlord who owns several properties and you probably won't like my advice.

I don't care about the fine intricacies of the law. If I am obligated to provide my tenants with certain items, they need to be in good working condition. If i give them a defective item and as a result, it causes the tenant to improperly incur an inordinate expense, that's on me and I'm going to voluntarily make good the tenant's loss. It's the right thing to do and just good business. Things like this are also the cost of doing business. We can't always be raking in the gelt. Sometimes we have to take a hit or two in the pocketbook for unexpected expenses.

I would sit down with the tenant, figure out an amount that is agreeable to the both of you and give it to them as credit on their rent. It's not going to kill you in the long run.