PVC pipe and fittings are an acceptable material for indoor geothermal piping. Manufactured PVC insulated manifolds with shut-off valves are a straightforward method of combining HDPE ground loops inside a building and transitioning to PVC mains. Geo-Hydro Supply offers a complete lineup of PVC insulated manifolds and a variety of transitions and adapters. Call us for custom designs not available from our store. We look forward to serving you!