The average hvac salary at Round Rock Isd was $48,932 , which is 12 percent lower than the average salary for this job in Texas, and 12 percent lower than the national average for this job . Hvac salaries at Round Rock Isd typically range from $41,995 to $52,624 (25th to 75th percentile). The highest reported hvac salary was $88,248. There are 17 employees at Round Rock Isd with the job title hvac.