We Are Not Happy Until You Are - All Work 100% Guaranteed! Horizon Plumbing, Heating & Air, is a locally-owned family business with over 20 years experience. We provide the highest quality residential and commercial service no matter how small the job. Whether you're in need of Plumbing or HVAC maintenance or installation or drain and sewer cleaning, we are there to provide you with the most dependable service available. We are serving Marin County, San Francisco and Sonoma County,