Stovepipes and shanty caps

By Tom Seymour | Feb 06, 2014
Photo by: Tom Seymour A heavy duty stovepipe remains safe for years.

Most folks tend to cleaning their chimneys and other woodstove-related maintenance activities in the fall. But by mid-winter, these same chores need attention once again.

It doesn’t take much for a stovepipe or chimney to acquire a thick, creosote buildup. Some preventive steps can help to extend the elapsed time between cleanings, though. One way to stave off creosote buildup is to faithfully use any of the creosote remover products sold commercially. These come in several forms, but the most effective, in my estimation, is the liquid kind.

Just spray a few bursts of liquid creosote remover on a hot fire every day and creosote, instead of adhering to the side of the stovepipe or chimney, will fall down into the stove. Perhaps all of it doesn’t fall, but a significant amount of it does, and this suffices to keep the chimney sweep at bay for yet a while longer.

Depending upon the stove, this creosote can either be gathered and disposed of in the trash, or it might just burn in the stove. For those who apply creosote remover daily, the slight amount of creosote falling into the stove poses little problem. But when large amounts of creosote fall down into the stove, lots of problems can occur. One is that creosote, being highly flammable, can catch fire and create a ripping blaze in the stove, often more than we bargained for.

Second, for stoves that have baffles situated directly under the exit pipe, creosote can fall down and collect on the baffle and eventually clog the chimney, filling the house with smoke. So it pays to keep a watchful eye on this throughout the wood-burning season.

Stovepipe points

I would rather have a dingy-looking, older stovepipe, one made of the heaviest available metal and in good condition, than a cheaper, new pipe made of thin, flimsy material. The cheap pipe is destined to fail before the old, heavy-duty one does.

Here’s something else about stovepipes. It doesn’t hurt to tap a stovepipe with a poker or other metal object and in fact, doing so accomplishes several things. First, the sound of a stovepipe being tapped or struck can tell us much about what’s going on inside. A hollow “thud” means that creosote has built up inside the pipe to unsafe levels. A tinny, resounding echo means that the pipe is fairly clean inside.

Also, tapping a stovepipe gives us an idea of its soundness. A stovepipe that has eroded from the inside to the point where it becomes compromised and unsafe, will flex and give at the point where it is tapped. This is a signal that the time has come to install a new pipe or pipes.

A good, strong stovepipe will again make that ringing sound and it won’t flex when hit. Of course tapping too hard will often make little dents and the stovepipe on my woodstove reflects this. They hurt nothing and show that the pipe has been continually tested for soundness.

Finally, gently rapping on a stovepipe is often sufficient to shake loose any clinging creosote and cause it to drop down the pipe and into the stove where it belongs.

Chimney caps

Problems with chimney caps occur primarily with prefabricated chimneys. Most makers of prefab chimneys offer their own chimney caps, made of the same stainless steel as the chimney. These are durable and long-lasting. But for use in a woodstove, are worse than worthless. That’s because these caps almost universally feature a thick, rounded cap set on a length of slotted pipe. These slots, for the most part, do not allow for sufficient air circulation.

These caps make it difficult to start a fire in the stove because they limit the draught. But that’s not their worst deficit. The impeded air flow invites creosote buildup and when enough creosote collects around the slotted vents, it plugs them up, making it hard to keep a fire going and also, creating a fire hazard.

The best thing to do with this type of cap is to not install it at all and return it for a refund. After that, go to a hardware or building supply store and select the heaviest, most durable shanty cap in stock. Shanty caps have a body, a section of pipe, that slides down into the prefab chimney. Attached to this body, are several upright metal straps or struts. A conical cap is fitted to the end of these straps and the distance from the end of the pipe to the bottom of the cap is always enough to allow for good draught and no creosote buildup.

Cheap, tinny shanty caps work as well as the more expensive models, but don’t last as long. They are good for only about one year. Acids in the smoke eat away at the thin metal and sometimes during severe windstorms, the wind rips the loosely-attached cap from the strapping. Heavier caps are more durable and don’t require replacing as frequently.

Finally, it pays to use the largest shanty cap possible. Sometimes it becomes necessary to use a reducer in order to install, for instance, an 8-inch shanty cap in a 6-inch chimney.

A woodburning system, stove, stovepipe, chimney and cap, is an ever-changing entity and as such, needs continual monitoring. So just because that chimney was cleaned last fall, don’t expect it and the rest of the system to go for the duration without additional maintenance. Please do make regular checks and in that way, be proactive regarding problems.

Helpful tip

To clean the glass door on a woodstove, use a wet cotton cloth dipped in wood ashes. This has just the right amount of mild abrasive material to safely wipe away soot. After cleaning and wiping with a clean cloth, spray a slight amount of liquid dishwashing detergent on the inside of the glass and it shouldn’t become blackened with soot ever again.

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