Testing Chemical Chimney Cleaning Products

1 / 7
The purpose of chimney cleaning products is to prevent this: a roaring chimney fire.
The purpose of chimney cleaning products is to prevent this: a roaring chimney fire.
2 / 7
Six identical
Six identical "airtight" steel stoves—equipped with DuraVent single-wall chimneys—were employed to perform the research on the four chimney cleaning products.
3 / 7
Diagram shows the stovepipe setup used in the tests.
Diagram shows the stovepipe setup used in the tests.
4 / 7
Photo shows creosote accumulation in the untreated control pipe after the cleaning phase. Heat has caused the creosote to dry and swell. Some of the flakes have already fallen to the bottom of the pipes.
Photo shows creosote accumulation in the untreated control pipe after the cleaning phase. Heat has caused the creosote to dry and swell. Some of the flakes have already fallen to the bottom of the pipes.
5 / 7
Photo of stovepipe  A1 was taken in Series 3 before cleaning started, and is of an untreated (control) pipe.  
Photo of stovepipe  A1 was taken in Series 3 before cleaning started, and is of an untreated (control) pipe.  
6 / 7
Photo of stovepipe  A2 was taken in Series 3 before cleaning started, and is of a treated pipe.
Photo of stovepipe  A2 was taken in Series 3 before cleaning started, and is of a treated pipe.
7 / 7
Photo shows creosote accumulation in a treated pipe after the cleaning phase. Heat has caused the creosote to dry and swell. Some of the flakes have already fallen to the bottom of the pipes.
Photo shows creosote accumulation in a treated pipe after the cleaning phase. Heat has caused the creosote to dry and swell. Some of the flakes have already fallen to the bottom of the pipes.

For the last century, chemical “chimney cleaners,” “soot removers,” and various other stovepipe “deposit modifiers” have been available to consumers searching for an alternative to the frequent chimney inspections and the sweepings that most coal- and wood burning appliances call for. Such chemical chimney cleaning products are usually dry mixtures of various compounds and/or elements, but at least one product is liquid (an aqueous solution). Whatever form they take, the compounds are put on (or sprayed into) the fire, and their manufacturers claim that the mixtures can help keep a chimney clear of creosote, while also serving to minimize the buildup of deposits inside a stove’s combustion chamber and on its heat transfer surfaces. Formulations are also available for oil-burning appliances, and large quantities of them are used today in some industrial furnaces and boilers.

There has, in recent years, been a good bit of debate about just how effective the chemical chimney cleaners are in reducing creosote buildup in residential flues, but there’s been little scientific evidence on which to base a decision. (To the best of our knowledge, the only previous study was conducted by the U.S. Bureau of Mines in 1929-30. That piece of research investigated the effects of such products only on coal soot, not on wood-generated creosote.) Therefore, in an effort to determine the effectiveness of chemical chimney cleaners, we tested four representative name-brands, simultaneously, in six identical “airtight” (steel) wood stoves. (One woodburner was used with each cleaner, and two served as untreated controls.) Creosote accumulation was measured by carefully weighing each flue before and after every test.

The chemical chimney cleaners we tested were selected from a large group of products on the basis of two qualifications. First, we wished to examine products that had strong national recognition and wide availability to make the results useful to as many consumers as possible. And second, we wanted to test compounds with widely varying compositions to analyze the effects of the several different chemical formulas employed by the various manufacturers. Consequently, some products that do have wide national recognition and availability weren’t included because they were similar in composition to other cleaners that we did test.

A typical test series began with the cleaning and weighing of each and every test section of the chimneys. Then, after the stovepipe had been reassembled, the stoves were loaded and lighted. A normal evaluation run consisted of firing for 8 to 12 hours per day, five days a week, with an average of three loads of wood being burned daily. The power output, wood type and moisture content, cleaner dosage, and length of test series were varied over a full seven months of testing.

Stack temperatures were continuously monitored, to insure that the stoves were all running alike, and to identify any chimney fires that occurred (since the ignition of deposits would have altered the creosote in the chimney and affected the weights that were being checked).

  • Published on Sep 1, 1981
Online Store Logo
Need Help? Call 1-800-234-3368