Selection, installation of suitable traps as long as there is steam through, there will be no freezing problems. But if the steam is broken, the steam condensate will create a vacuum in the heat exchanger or in the mains. This will prevent the free flow of condensate from the system before freezing occurs. So, install a vacuum breaker between the drain and the trap. If not from the trap to the return pipe is not the use of gravity discharge, traps and discharge lines should be manually discharged or discharge pipes with anti-freezing measures automatically discharge. Also, when multiple traps are installed together at the trap station, the traps are insulated to prevent freezing. Antifreeze measures are: 1. Traps do not choose the size is too large. 2. Keep trap drain as short as possible. 3. Tilt the trap drain down to speed up the gravity discharge. 4. Trap drain and condensate return line plus insulation. 5. When condensate return line exposed to atmospheric conditions, should consider adding heat pipe. 6. If the return pipe is raised, the vertical discharge pipe should be adjacent to the discharge pipe at the upper part of the return pipe header, and the discharge pipe should be insulated from the discharge pipe of the trap
