Seconding one of the responses below, part of the due diligence process is determining what the buyer is actually getting in their purchase. Certainly with a net-lease investment one is buying not only the physical land & improvement but also the expectation of a certain income.
I have found that it is necessary, irrespective of the language in marketing materials, to find out what the specific terms mean to the specific owner/landlord, i.e., triple net may mean absolute triple net to some landlords while to many tenants, despite the term "absolute triple net" may have carve-outs such as structural, parking areas, et al, that the landlord is responsible for. (Also, most sellers' and brokers' marketing materials will have disclaimers that indicate that, in effect, it is up to the purchaser to investigate the property and not rely wholly on marketing materials.)
My recommendation would be to review the lease document and determine if this cost is addressed and if not, determine from the prior owner, how has it been handled in the past.
Many of us have had landlords and tenants bicker over HVAC maintenance, especially if the lease outlines that the landlord is responsible for replacement and the tenant for repair. In such a case the landlord will delay the replacement and try to convince the tenant it needs repair while the tenant will take the opposite stance. Another category that often causes conflict if not spelled out precisely in a lease are capital items versus operating items.
Ideally, these are elaborated in the lease document so as to reduce ambiguities.
I hope this is helpful.
Jul 8, 2012