I'm having a pellet stove installed this week. I've spoken to the dealer a few times about having an OAK put in at the same time. He is adamant that an OAK is not needed. From what I have read here, I'm thinking that I should get one anyway. My reasons: 1. The manual recommends having one (M55 Cast Insert). 2. Our house is very tight. We had the door blower test done recently and the testers were surprised at how tight the house was. 3. It's easier to do it during the initial install. 4. The OAK can be run up the chimney, so there's no need to cut a hole in my chimney. I'd like to rely on my dealer's technical expertise, but it seems that dealers never want to install OAKs. Why is this? Am I right in demanding an OAK?