For side wall venting millivolt gas water heaters. Excellent for electric-to-gas conversions, renovations, new construction or for replacing old chimneys. Vents up to 75 equivalent feet and includes: Post Purge Relay/Timer, 24V Solenoid Valve, Gas Pressure Switch, Spill Switch and Vent Hood. Factory prewired electrical box and 24V Control Cables eliminate need for an electrician. Inputs from 25,000 to 120,000 BTU/hr.