Chimneys are made to protect you            

A chimney is a structure made of masonry or metal,  which surrounds and supports a flue or multiple flues that vent products from gas, oil, or solid fuel appliances or fireplaces. The flue is the inner part of the chimney that contains and vents the products of combustion. Flues are made of clay, as in the case of most masonry chimneys, or of metal, as in the case of prefabricated or manufactured chimneys. One way to think of a chimney and flue within it is to think of it as a structure to protect you. That is an important function of all chimneys no matter what kind of appliance or fireplace they serve.

Remember, the main purpose of a chimney is to vent the products of combustion from your home. That function is crucial because the products of combustion contain hazardous and noxious gasses. One of the hazardous gases your chimney needs to remove is carbon monoxide.

Carbon monoxide is a colorless, tasteless gas that can cause serious illness or death when it is present in sufficient amounts. It is responsible for hundreds of deaths and countless illnesses every year in homes across America. In  many cases, carbon monoxide in the home originates in a furnace or other burning appliance and finds its way into the house due to inadequate venting.

What causes inadequate venting? There are several possibilities. One is that the flue has become blockedfrom debris falling into the chimney due to a deterioration. Or it may be the result of nests from animals and birds. Carbon monoxide can also seep into the house through cracks or holes in chimneys, where moisture, chemical residue or chimney fires have damaged them.

The other important function of chimneys, especially those serving solid fuel burning appliances like wood stoves or fireplaces, is to keep excessive heat from combustible materials that surround the chimney. Heat or flames from a chimney fire can escape through cracks in the clay liner or through damaged or missing mortar joints of a chimney. They can then ignite surrounding combustible framing members of a house.

Chimney fires occur within the structure of the chimney itself. They happen when hot flue gases or cinders ignite creosote on the walls of an unclean chimney flue. Creosote is a natural byproduct of burning wood. It is highly flammable and will accumulate on the inner walls of the flue under certain burning conditions.

Even without the occurrence of a chimney fire, framing members surrounding a chimney can have their molecular structure altered and become more flammable when exposed to excessive heat over long periods of time. This process is know as pyrolysis. Once wood is sufficiently pyrolyzed it can ignite at relatively low temperatures and become a significant fire hazard.

So, you can see, a well structured chimney and flue are designed to offer protection to your family and home from the dangers of noxious gases such as Carbon Monoxide, and from the high levels of heat present in the flue gasses of solid fuel burning appliances and fireplaces. But, like all structures, they must receive regular inspections and maintenance in order to maintain their integrity and to continue doing their job.

How To Maintain a Properly Functioning Chimney

A proper evaluation should also include a visual inspection of the flue inside the chimney. Ideally, that internal inspection should be done with a video inspection device. Such devices allow chimney professionals to detect even small cracks in the chimney liner that may not be seen by the naked eye. According to the National Fire Protection Agency code, cracked chimney liners constitute a significant safety hazard and must be replaced.

All connections from the burning appliance to the chimney should also be thoroughly inspected.

If inspections described above indicate the possibility of a chimney deficiency, then a more thorough inspection of the chimney and the structural members surrounding it may be required.

Annual inspections by a qualified chimney professional should go a long way towards heading off serious chimney problems and the need for expensive repairs.

It is important to note that for an inspection to yield the best results, the flues to be inspected will need to be cleaned first. Otherwise, soot creosote, or other residue might mask physical problems with the flue or the flue liner.

What can you do between Inspections To Keep Your Chimney Operating Properly?

When using wood burning appliances avoid banking the fires and closing the dampers in order to prolong burning, Slower, cooler burning wood fires are the primary contributor of creosote in chimneys. Be certain to burn wood that has been properly aged. Burning green wood also contributes to creosote in chimneys.