We're the Geothermal Source in Granville! Granville residents in the know look to Westin Air for all their geothermal heating and cooling needs. They trust us to give not only the proper installation and service but also the insight to help them maximize the potential from their geothermal systems. Thinking about a geothermal system of your own? Give our nifty little Geothermal Savings Calculator a whirl. Just load it with your data and marvel at the results. Then, contact us, the Granville, Ohio, geothermal professionals at Westin Air.