Built-in tank repo This is Viessmann’s electric boiler. It’s their now, with some modifications to programming on a NextGen boiler and purchase of the company, it’s Viessmann now. I installed this electric boiler in November 2022. Within the last week or so the built-in expansion tank failed. Thats annoying. The replacement does require full removal of the boiler. Also annoying. Not difficult but nonetheless time consuming. An external tank could be plumbed in very easily but we decided against