Hi everyone, I was wondering if anyone knows the regulations for fitting undercounter unvented water heaters?. I'm gsr but haven't got my ticket for unvented cylinders but I'm sure I've heard that the ticket isn't required for unvented appliances under a certain size. First time I have ever been asked to fit an instant water heater but not sure wether or not I can do it legally. Any help or info would be appreciated, thanks.