Relining Guide

Question: I was told I need my chimney relined. How do I know this is true and why is it so important?

Answer: To know for sure you can have a closed circuit video inspection of the interior of your chimney and watch it yourself. Sometimes flaws can be seen looking up or down a chimney, but theses views are limited. An internal video scan will often reveal flaws not found by other methods of inspection.
  If there are cracked terracotta flue liners, spaces between sections of terracotta flue tiles, flaking or pitted tiles, or misaligned tiles (sections that are not set directly on top of each other,) relining is necessary before the chimney is used. The National Fire Protection Agencies guidelines state this very clearly.
In the case of a  fireplace, wood stove, coal stove or pellet stove, do not use the appliance until defects in the liner are corrected. In the case of a furnace, water heater, or any vented appliance which is in use, relining should be done immediately.

Why?

It is dangerous not to do so. Flame, heat, sparks, smoke, and carbon monoxide all pass through chimneys. If there is a reason to suspect the liner is not airtight or is deteriorating, these could be entering your home or you could be at risk.

But I have used my chimney for years with no trouble, why should I worry now?

For many reasons. If you have an accumulation of soot building up behind crevices where your liner is compromised, a cleaning will not remove it. A video scan may reveal the flaw in the liner, but not the soot that has passed beyond it. This hidden soot can ignite outside the liner in an unprotected area. Heat and sparks can also penetrate beyond a defective liner into an unprotected area. If excessive heat or sparks come in contact with these accumulations of soot  a house fire could result.

Accumulations of soot and pyrolysis (the drying, charring and chemical reactions of flamable substances due to prolonged exposure to heat which lowers ignition temperatures) can take years or even decades to develop. The ignition temperature can eventually drop to well under 300 degrees. After years of no problems a fire may result.

I like to give this analogy-  A 55 year old may never have had a major health problem. Why should he or she worry about their health? For the same reason someone who has an old chimney should be concerned. Some  conditions that  pose a serious risk, develop gradually over time. Even masonry deteriorates with age. A masonry chimney will sometimes show signs of deterioration within 10 or 15 years or less and few will pass a video inspection at 30 to 40 years of .

But I have a gas furnace and there is virtually no soot building up and I don’t think sparks are an issue. Why should I worry?

In the worst of cases, a badly deteriorated flue liner could collapse and your house could fill with lethal amounts of carbon monoxide in minutes. In the case of minor flaws, slow seepage of fumes could result in unhealthy or lethal amounts of carbon monoxide as well (not to mention water vapor, spotting or wet walls, etc.) The temperatures emitted from an oil or gas furnace are more than enough to start a fire as well.

Won’t my carbon monoxide detector tell me if I have a problem?

Not necessarily. Low batteries, power outages and mechanical failures all can cause your carbon monoxide detector to fail. Placement of the detector and/or the location you happen to be at in your home can also hinder the ability of the alarm’s to inform you of an immediate danger.

Why is carbon monoxide (CO2) referred to as “The Invisible Killer?”

Pain indicates you are having a problem, but it may not indicate the source accurately. You may also have a severe medical problem developing and not feel anything at all. Carbon monoxide has bee termed the invisible killer because it is invisible and odorless and the even the odors added to natural gas to make it detectable before it is burned, disappear when it is burned, so you cannot smell burned natural gas. (Burned natural gas consists of carbon dioxide, carbon monoxide and water vapor – all of which are odorless. I have noticed humidity and musty felling or smell in homes with severe leakage of gas furnace exhaust fumes containing carbon monoxide into the home. Do not wait for this to in your home. It is not generally noticeable and can be mistaken for many other things. Many basements feel that way all the time! Prolonged exposure to even small quantities of CO can be lethal. Carbon monoxide detectors are not perfect. They fail, they only test the area they are located in and most importantly they can only warn you after leakage into your home has begun.