Why nanai black for commercial real estate services? NAI Black’s selection of commercial brokerage and property management services for owners, investors, developers, and occupiers demonstrates our broad range of expertise and market knowledge. Let us design a scope of real estate services that is specifically tailored to meet your needs.How do i contact rinnai customer support? Rinnai Customer Support 1-800-621-9419. Whether you have a question about a Rinnai gas appliance, need support or would just like to give us some feedback, we’re happy to hear from you.Why nanai black? NAI Black is a proven leader in commercial brokerage and property management services, serving the Inland Northwest region for over 50 years.