“My boiler has two of these, one of which is on top of my water heater. I have hard water, and I find these fail after a few years. Probably not a design flaw, but just my water. It's quick and easy to replace. You don't need to hire your heating company or plumber to replace, and you can save a lot by doing it yourself.”
“It's an air vent. No big deal. But what makes it great is the customer service gives. They weren't sure of the model that would be compatible with my indirect water heater so they contacted the manufacturer. They followed up with an email and a link to the part I needed. 6 stars for you customer service. You get "customer service."”