nostr:npub1yacj26q9parem5fqf2s3ym9xkxghkk0w2jc63aglsnl2fmyhshnszgla7e nostr:npub163w0x42e9v5halescch6sqe3k4lzmjlghsqpejapgfnmeucjnekshmlq6z nostr:npub1lllv638gr9ax6uaf3n3hy4aqp5e7pvrmz6g68x6rckuh7urx75dq5k5409 No, it doesn't. The one I linked (which is the one I own) is a single unit. It replaces your hot water cylinder. That is literally all there is.

It has a pipe coming in for ambient air and a pipe going out for cold air from the heat exchanger. They just need to vent to the outside. Can do that via an existing chimney or flue.

There is no external fitting of any kind. It's a single unit.