Tankless water heaters don't require an electrician to install them, but it's always a good idea to have a professional do the installation. That's because tankless water heaters are more complicated to install than traditional tank-type water heaters, and there are a few things that can go wrong during the installation process. For example, if you don't install the tankless water heater properly, it could cause damage to your home's plumbing system. So it's always best to call in a professional when installing a tankless water heater.