Bosch, Westinghouse, Carrier and Lennox are some highly rated oil-fired furnace boiler brands. Many of the top rated brands also produce some of the most energy efficient oil boilers rated by Energy Star as of 2015. All of the manufacturers produce several models in different sizes.
Bosch Greenstar series oil boilers are small, quiet, environmentally friendly and have an annual fuel usage efficiency rating of 95 percent. Westinghouse's Fire Tube Boilers are extremely efficient with a 97 percent rating, and the company's downward tube design provides a low-pressure drop and promotes self-cleaning. The Carrier BMW series has a lightweight and compact wall-mounted design that is 95 percent efficient. The Lennox GWM boilers have a 95-percent rating as well and have 15-year limited warranties.