Rheem Manufacturing Company is an American privately held manufacturer that produces residential and commercial water heaters and boilers, as well as heating, ventilating and air conditioning (HVAC) equipment.he company is one of the largest manufacturers of both water heating and HVAC equipment in the United States, and also produces and markets products in Argentina, Armenia, Australia, Bahrain, Brazil, Canada, Iraq, Kuwait, Mexico, New Zealand, Oman, Qatar, Saudi Arabia, Singapore, UAE, and Ukraine. Contents.