Jan 05, 2021 · Rheem Water Heater Manuals. It can sometimes be difficult to find the correct instruction manual for your device, particularly for older, discontinued models. Use the search bar below to find your specific Rheem Water Heater Manual. You can enter the model number, name or description. We’ve also included images to help.. Rheem Manufacturing ranks as the global leader in the manufacture of high-quality, sustainable, and innovative water heaters, tankless water heaters, air conditioners, furnaces, pool heaters, and HVAC systems for residential and commercial applications, and is a full member of AHRI, the Air-Conditioning, Heating, & Refrigeration Institute.