A8. Just like most tankless water heater vennting of Rinnai tankless water heaters require a Rinnai trained professional and plumber. Improper installations can not only be hazardous but also it will affect the warrant period of Rinnai. It is best not to install by oneself and take the help of a licensed contractor. Here is a detailed Rinnai Tankless Water Heater Troubleshooting Guide.