The Baystate Pool 420020024S Stack Flue SCV Kit is a specialty component intended for use in pool and spa heating systems. This equipment is required for proper ventilation of gas-fired heaters, resulting in safe and efficient operation. The stack flue SCV regulates the flow of exhaust gases from the heater to the outside environment, reducing the possibility of backdrafts and increas... https://www.usapoolshop.com/420020024s-baystate-pool-stack-flue-scv-kit