A real estate broker in Phoenix says he has sold three manufactured home communities in the last two months to out-of-state investors.  Russ Warner says the growing senior presence and the stability of the investment are fueling demand across the country.  He notes that investors who have left this portfolio in the past are returning, in part because the demand for manufactured housing is stable and likely to grow, especially among seniors.  The three properties in suburban Phoenix sold for nearly $20 million total, and ranged from 69 homesites to 201.  As reported in GlobeSt.com, Warner says the income from manufactured home communities, which typically have a 90% occupancy, is steadier than that from apartment investments.