What is the difference between an anti-syphon trap and a re-sealing trap?
A re-sealing is designed to allow air to pass through the water seal under negative pressure but will retain sufficient water to ensure the minimum depth of seal is retained. Whereas an anti siphon trap has a small mechanical valve, which opens under negative pressure. Both versions will break the syphonic action thus protecting the water seal. Note. the re-sealing trap may be noisy.
