The frequency of oil replacement in the thermal oil heater should be according to the actual situations.

1. The heat medium oil goes bad. If the heat medium oil in the thermal oil heater goes bad or is polluted, which lowers the oil quality, the heat medium oil should be replaced.

2. The temperature rise slows down. If the temperature rise of the boiler equipment slows down without other problems, the heat medium oil should be replaced.

3. The technical indicators is abnormal. Generally, when the residual carbon is greater than 1.5%, the acid value is greater than 1.5, or the kinematic viscosity is greater than 50, the heat medium oil should be replaced once one of the indicators exceeds the standard.