Safety Info

Safe Home Heating

It’s so easy and automatic that  people just don’t think about it. Every year, when the weather turns  cold, homeowners reach for household thermostats, flip a switch to turn  on the heat and set the temperature to 68 or 70 degrees. Little thought  is given to whether the furnace exhaust system – the chimney and connector pipe – is ready to provide safe, effective service. 

Consumer confidence in the  convenience and safety of today’s home heating systems is usually  well-placed. The oil and gas heating industries have achieved impressive  safety records. Nonetheless, over 200 people across the nation are  known to die each year from carbon monoxide poisoning caused by problems  in the venting – out of their homes – of toxic gases produced by their  heating systems. This is according to statistics compiled by the  U.S. Consumer Product Safety Commission. Other agencies estimate actual  numbers at between 2,000 and 4,000.

In addition, around 10,000 cases of carbon monoxide-related “injuries” are diagnosed each year. Because  the symptoms of prolonged, low-level carbon monoxide poisoning “mimic”  the symptoms of common winter ailments (headaches, nausea, dizziness,  fatigue, and even seasonal depression), many cases are not detected  until permanent, subtle damage to the brain, heart and other organs and  tissues has occurred. The difficulty of diagnosis also means the numbers  of people affected may be even higher.

Fortunately, regular chimney system inspection and maintenance can prevent poisoning incidents like these. 

What Carbon Monoxide Does to You 

Too much carbon monoxide in your  blood will kill you. Most of us know to try to avoid this. Less well  known is the fact that low-level exposure to this gas also endangers  your health.

One of the truths of our human bodies is that, given a choice between carbon monoxide and oxygen, the  protein hemoglobin in our blood will always latch on to carbon monoxide  and ignore the life-giving oxygen. Because of this natural chemical  affinity, our bodies – in effect – replace oxygen with carbon monoxide  in our bloodstream, causing greater or lesser levels of cell suffocation  depending on the intensity and duration of exposure.


The side-effects that can result  from this low-level exposure include permanent organ and brain damage.  Infants and the elderly are more susceptible than healthy adults, as are  those with anemia or heart disease. 

The symptoms of low-level carbon  monoxide poisoning are so easily mistaken for those of the common cold,  flu or exhaustion, that proper diagnosis can be delayed. Because of  this, be sure to see your physician about persistent, flu-like symptoms,  chronic fatigue or generalized depression. If blood levels of carbon  monoxide are found to be high, treatment is important. 

Meanwhile, it makes good sense to  put heating system inspection and maintenance on your annual  get-ready-for winter list. Prevention is the best cure. 

Causes of Heating System Problems


Why is poisoning from carbon  monoxide on the rise? And why does it stem primarily from home heating  systems that – at first glance – seem the same as those that have been  used safely for years? 

  • Today’s houses are more  air-tight. Homeowners are aware of the cost of heating drafty homes and  have taken steps to seal up windows, doors and other areas of air  infiltration. Consequently, there is less fresh air coming into a home  and not as many pathways for stale or polluted air to leave it. And,  when furnaces and boilers are starved of the oxygen needed to burn fuels  completely, carbon monoxide is produced.
  • Manufacturers have designed new,  high-technology heating appliances whose greater efficiency helps us  save money, conserve natural resources and decrease environmental  pollution. However, the new breed of high-efficiency gas and oil  furnaces – when vented in to existing chimney flues – often do not  perform at an optimum level. The differences in performance create  conditions that allow toxic gases to more easily enter home living  spaces. 

The above conditions point out a  number of older, ongoing problems that still require detection and  correction in order to prevent toxic gases from filtering into the  house. These include damaged or deteriorating flue liners, soot  build-up, debris clogging the passageway, and animal or bird nests  obstructing chimney flues. 

Caring for Your Chimneys & Flues 

When gas and oil burn in vented  heating systems – in order to produce household heat – the dangerous  fumes that are by-products of combustion range from soot (particulate  matter) to nitrogen dioxide (also toxic) to acidic water vapors formed  when moisture condenses. None of these pollutants should be allowed to  leak from the chimney into your living space. 

In addition to carrying off toxic  gases, chimneys also create the draft (flow of air) that provides the  proper air and fuel mixture for efficient operation of the heating  appliance – whether a furnace or boiler. Unfortunately, many chimneys in  daily use in homes throughout the country either are improperly sized  or have conditions that make them unable to perform their intended  function. 

Chimney Problems to Avoid 

Oil and gas furnaces have  distinct burning characteristics and produce different combustion  by-products. However, the chimneys and connector pipes that serve them  share common problems. Both systems are subject to weathering, animal  invasions, deterioration and rust-out and the accumulation of nest  materials and debris. Both require regular care and maintenance. 

Oil flues need to be cleaned and  inspected annually because deposits of soot may build up on the interior  wall of the chimney liner. The amount of soot depends on how well-tuned  the furnace is and whether the house provides sufficient air for  combustion. Excessive soot causes problems that range from chimney fires  … to flue deterioration … to chimney blockages that direct toxic fumes  back into the house and cause inefficient furnace operation. See the  brochure from the CSIA specifically relating to oil-burning appliances.

Natural gas is a  clean-burning fuel, but today’s high-efficiency gas furnaces pose a  special problem. The fumes they produce are cooler and contain high  levels of water vapor, which are more likely to cause condensation than  older models. Since these vapors also contain chlorides picked up from  house-supplied combustion air, the flues are subjected to more corrosive  conditions than before. 

Even worse, many gas appliances  use chimneys that once served oil furnaces. If the liners of these  chimneys are made of terra cotta (fired clay commonly used in chimney  construction), bits and pieces of them slowly flake off under corrosive  conditions. The combination of water-laden gas vapors available to mix  with old oil soot deposits speeds this process, and debris that can  block the chimney builds up at the bottom of the flue. 

To the extent that problems with either of these heating systems interfere with the flow of toxic gases and particles out of the house, they may also force carbon monoxide, fumes and possibly soot into the  living spaces of your home. They may cause a one-time, high-level  exposure situation or release smaller amounts more regularly over a  longer period. These problems should never be ignored. 

Preventing Problems 

In the United States, numerous  agencies and organizations now recognize the importance of annual  heating system inspection and maintenance in preventing carbon monoxide  poisoning. The U.S. Consumer Product Safety Commission, the U.S.  Environmental Protection Agency, the National Fire Protection  Association, and the American Lung Association – are some of the  organizations that now encourage the regular maintenance of home heating  systems and their chimneys in order to keep “the silent killer” at bay.  

A well-tuned furnace or boiler –  connected to a venting system or flue that is correctly-sized,  structurally sound, clean and free of blockages – will operate  efficiently and produce a warm and comfortable home. An overlooked  heating system can produce death and heartbreak.

Considering the risks involved  when gas or oil systems are neglected – and the benefits that accrue  when they are properly maintained – you would do well to have your  chimneys checked annually by a CSIA Certified Chimney Sweep® and swept  or repaired as needed. This can keep illness or death from carbon  monoxide poisoning from claiming you or those you love.