I am debating on putting in a damper or not with my install. Mainly so I can have more control over the fire in the event of a runaway/overfire so I can shut it down completely. From stove top to rain cap will only be about 14 feet straight up. However we get extreme colds here and when it is super cold every nook and cranny have super drafts and I am sure a 6 inch pipe will be the same. My main concern is cleaning can they be easily removed for cleaning .If I put one in it will be about a foot above the stove stop however I bought a sooteater and will be doing bottom up cleaning so I would imagine with the sooteater you could open the damper completely and work the head through to clean the rest of the pipe.