The median annual wage of stationary engineers and boiler operators was $52,140 in May 2010. The median wage is the wage at which half the workers in an occupation earned more than that amount and half earned less. The lowest 10 percent earned less than $32,640, and the top 10 percent earned more than $73,580.

Starting pay for apprentice stationary engineers and boiler operators is typically 45 percent to 60 percent of that of a fully trained worker.

Many stationary engineers and boiler operators are members of a union.

Most stationary engineers and boiler operators work full time during regular business hours. In facilities that operate around the clock, engineers and operators usually work one of three 8-hour shifts on a rotating basis. Because buildings are open 365 days a year, many must work weekends and holidays.

Source: Bureau of Labor Statistics, U.S. Department of Labor, Occupational Outlook Handbook, 2012-13 Edition