I have a BuckStove brand woodburner. I have a 6" Magic Heat brand heat reclaimer mounted 14" above top of stove, the following problem occurs with or without the Magic Heat installed. (By the way, Magic Heat is very well built, and an excellent source of extra heat that would be going out the flue otherwise, about $150.00 - $200.00 !!, just an experienced opinion, not an advertisement ). PROBLEM: creosote runs out of joints between 2 foot lengths of pipe outside. I can tape joints, but fear that might cause too much buildup on the inside of my outdoor flue. I burn mostly seasoned ash, and flue draws very well. Any advice/ opinions appreciated.
Excellent question, there is a lot to go over here so I'll answer your question in several parts and hopefully you'll gain some important insight.
First, I'll cover the Magic Heat reclaimer that you are using. Heat reclaimers are notorious for causing excess creosote build-up. The reason for this is that they cool the temperature of the flue gases which leads to condensation in the flue that causes excess creosote. Because you mentioned that you have a problem with or without the Magic Heat, I'll assume that another issue is at work here. But I can assure you that the heat reclaimer is not helping matters any. The only time that I would recommend using one is with an old style potbelly stove where it is difficult to control the temperature because they burn so hot. Even then, it is important to do frequent cleanings to reduce the likelihood of a chimney fire.
The other causes that are potentially contributing to your problem would be inefficient burning, unseasoned wood and a chimney that is not properly insulated and/or in a poor location.
You mentioned that you are burning "mostly seasoned ash." Does this mean that the ash is mostly seasoned? Or do you mean the most of the wood you burn is seasoned ash in addition to other seasoned wood? I ask because it is extremely important to only burn seasoned wood to avoid creosote problems.
Inefficient burning is another typical culprit leading to excess creosote. When a fire is starved of oxygen it will smolder, burn inefficiently and lead to excess creosote. People do have a tendency to burn inefficiently sometimes to have fires last longer to save on fuel costs. The problem is that you pay for it with creosote and possible chimney fires. Since I do not have any experience with your particular model of wood stove, I can't speak to it directly but it's a good idea to consult the stove manual to make sure that you are burning efficiently according the manufacturer's recommendations.
The third common problem is with chimneys. I'm not exactly sure from your description, but it sounds like your have a metal chimney that runs on the outside of your house? If that is correct, the chimney is not in an ideal location. Ideally, a chimney should be inside the house and leave near the peak of the roof. This keeps the chimney flue warmer and reduces the likelihood of creosote build-up. If this is the case, I realize that moving the location of your wood stove/chimney is probably not a realistic solution, but I recommend making sure that you have a well insulated chimney. Because you mentioned that the flue draws very well, it sounds like the chimney may not be your problem but it's still worth a look.
In regards to the creosote running out of the stove pipe, it sounds like a problem with the pipe installation. Most stove pipes have a male and female end. The male end should always point down and the female end should always be up. This orientation ensures that creosote will always run down the inside of the stove pipe rather than leak on the outside of the pipe.
In conclusion, you definitely have a problem somewhere in your setup. It will probably take a little investigation to figure out what exactly is causing the problem. I do urge you to reconsider the heat reclaimer, as they are notorious for causing excess creosote and consequently dangerous chimney fires.
I hope this helps and check back in with us when you find a solution. Thanks!