7. Carbon Monoxide and Detectors

by | Carbon Monoxide

Man Cleaning the Duct

        With the winter season approaching we are closing up our homes to conserve heat and limit cold drafts, we need to pay close attention to the quality of air that we are breathing. Assuming now that your furnace and hot water tank have been serviced and are clean and operating at peak efficiency, you have checked your attic for proper ventilation and adequate insulation, let’s not forget about the devices that will warn us in case something changes with the air we are breathing, namely, carbon monoxide detectors and smoke detectors. They are silent sentinels, waiting patiently on the ceiling to warn us if something is not right with the air in our homes. All they ask of us is that we keep them clean, don’t let them expire, keep fresh batteries in them or ensure that they have an un-interrupted power supply, so they can scream out a warning to us when something is not right.

It is always sad to hear that someone has lost their life due to CO poisoning. I have personally experienced the grief and heartbreak a family has felt due to the loss of a youngster to CO poisoning. But every year it seems to happen again, why??

 Let’s take a look at where it comes from. Every fuel-burning appliance produces some levels of carbon monoxide. Carbon Monoxide is produced when fuels such as natural gas, gasoline, oil, propane, wood or coal are burned. The danger is magnified when combustion gasses are not properly ventilated, or when the CO can’t dissipate because of a blocked or dirty chimney. CO could also build up to dangerous levels when fuel-burning generators, space heaters, barbecues, grills or other appliances intended for use outside, or in well ventilated spaces, are brought indoors or into less ventilated spaces such as small rooms or garages. All too often, portable fuel burning heating or electrical generating equipment are improperly used when our home systems fail, good intentions can lead to disastrous results. Large exhaust appliances, such as clothes dryers and range hoods, can depressurize a home, creating a situation where CO from your furnace or hot water tank that would normally vent outside is pulled back down the chimney and into the home. I have had experience with this when I replaced a low-volume bathroom fan with a higher volume fan, due to a mould issue caused by poor ventilation. I was aware of this situation, and upon checking the hot water tank, the higher volume fan when operating, created a back-drafting situation through the hot water tank vent pipe. This situation was rectified by increasing the fresh air intake pipe in the utility room to a larger size. This made it easier to balance the difference in air pressure for the higher volume bathroom fan. You should also be aware that when increasing the air exhaust volume of any appliance or fan within your home, the outside temperature has a large part to play as well. In the milder temperatures, it is easier for the hot gases from the appliance to find their way up the chimney and initiate the drafting process. When the temperatures are down at freezing or below, these gases may not have enough lift to clear the cold heavy air in the chimney and warm the chimney enough to initiate enough uplift for the drafting process to begin. It may take several long minutes for the appliance to begin drafting properly, all the while dumping poisonous CO into your basement. If you ever decide to have a furnace upgrade, from a mid efficiency naturally drafting furnace to a high-efficiency furnace which pulls its combustion air from the outside and exhausts the spent gases to the outside through an induction fan, and your hot water tank continues to use the same chimney, the existing chimney must be fitted with a smaller liner to match the same size as the exhaust flue on the hot water tank. This is because the chimney has been sized for two appliances, one being the furnace that is now removed, the chimney is now too large for a single hot water tank. If this chimney is not reduced in size, the exhaust gases from the hot water tank will linger within the existing chimney for a longer period of time, cool off and form condensation. This condensation is acidic, and will run down the exhaust venting and eventually corrode holes in your pipes which will allow combustion gases to escape into your environment.

                          10 Signs of a Possible Carbon Monoxide Leak into your Home.

     Despite the fact that you can neither smell nor see or taste the gas, there are a few signs you can look for to detect a carbon monoxide leakage or buildup in your home. CO is very dangerous, and is often called the “silent killer” because it is hard to detect it until it is too late. Though many victims of CO poisoning recover with treatment, severe cases can cause permanent brain damage and/or death.

  1. Dripping or heavy condensation on the windows where the appliance is installed – this can be a great indicator if you have taken measures to reduce moisture production, though it could also imply that the humidifier is set very high.
  2. Sooty or brownish-yellow stains around the leaking appliance exhaust.
  3. Stale, stuffy, or smelly air, like the smell of something burning or overheating.
  4. Soot, smoke, fumes, or back-draft in the house from a chimney, fireplace, or other fuel burning equipment.
  5. The lack of an upward draft in chimney flue.
  6. Fallen soot in fireplaces, have it cleaned.
  7. Solid fuel fires burning slower than usual.
  8. The smell of unusual gases in your house. While carbon monoxide is odourless, sometimes it is accompanied by exhaust gases you can in fact smell.
  9. A pilot light that is frequently blowing out, indicates a back-drafting condition down the chimney.
  10. A yellow burner flame instead of the usual clear blue flame, though this is not applicable to natural gas fireplaces that intentionally generate the yellow flame for aesthetic purposes.

If you’re late detecting the CO leakage, you may need to take fast action if you notice early symptoms of carbon monoxide poisoning, like tightness across the forehead, followed by pounding of the heart and headache. When progressive poisoning occurs, the victim’s face becomes extremely red accompanied by dizziness, weariness, and mental changes.

However, very concentrated CO may cause the victim to pass out without feeling any of these symptoms.

Carbon Monoxide Safety:

The first line of defence against carbon monoxide poisoning is making sure that your home’s heating equipment is being inspected on an annual basis: including gas appliances, chimneys and vents. CO alarms are a must have that need to be installed on every level of the home and tested regularly. Also, you should never use grills, BBQs, or charcoal fuel burners in unventilated spaces, keep your rooms well ventilated at all times.

 Why it’s so Deadly ?

CO poses a particular danger because without a working carbon monoxide detector in the vicinity, there are no obvious signs it may be building up around you. It is invisible, and can sap the blood of its ability to absorb oxygen. When you breathe in carbon monoxide, it builds up quickly and combines with the blood to produce carboxyhemoglobin’ (COHb), which reduces the ability of blood to carry oxygen. Without oxygen, body tissue and cells can’t function. “The brain is extremely vulnerable to oxygen deprivation,” the Canada Safety Council says.

What the symptoms are:

It could be easy to confuse the symptoms of carbon monoxide exposure with the flu or other medical problems. At low levels of CO exposure, Health Canada says, you might have a headache, feel tired or short of breath, or find your motor functions impaired. At higher levels of exposure, or at lower levels for a long time, symptoms might include chest pain, feeling tired or dizzy, and having trouble thinking. Convulsions, coma and death are possible with high levels of exposure, Health Canada says. If the levels are very high, death can occur within minutes.          

CO concentrations and Symptoms:  ppm = Parts per Million

35 ppm (0.0035%) Headache and dizziness within 6 to 8 hours of constant exposure.                                                    

    100 ppm (0.01%)  Slight headache in two or three hours.

    200 ppm (0.02%)  Slight headache within 2 to 3 hours, loss of judgement.

    400 ppm (0.04%)  Frontal headache within 1 to 2 hours.

    800 ppm (0.08%)  Dizziness, nausea and convulsions within 45 minutes, insensible within two hours.

    1600 ppm (0.16%)  Headache, rapid heartbeat, dizziness and nausea within 20 minutes, death in less than two hours.

    3200 ppm (0.32%)  Headache, dizziness and nausea in 5 to 10 minutes. Death within 30 minutes.

    6400 ppm (0.64%)  Headache,  dizziness in 2 minutes. Convulsions, respiratory arrest, and death in less than 20 minutes.

    12,800 ppm (1.28%)  Unconsciousness after 2 to 3 breaths. Death in less than three minutes.

Some carbon monoxide facts:

 1)  Gas sensors in CO alarms have a limited lifespan, generally less than 10 years. The test button on common CO alarms only tests the battery, not the CO gas sensor.

  2) Some believe that CO is heavier than air, and detectors should not be placed on the ceiling or high on a wall. This is incorrect, CO is slightly lighter than air. CO has a molar mass of 28.0, and air has an average molar mass of 28.8. The difference is so slight that CO is found to eventually distribute itself throughout indoors. It is worth mentioning that CO indoors is usually generated from incomplete combustion and therefore travelling in a warm airstream. Warm air is more buoyant and will rise. Coupling this fact with the knowledge that CO is lighter than air, that would suggest that a CO detector should be located on the ceilings. Always follow manufacturer’s installation instructions.

3) The most significant source of CO is formed during combustion when there is insufficient oxygen to aid in complete combustion. This scenario would be a hot water tank in a closet with limited fresh air. A furnace located in a crawlspace or attic with limited fresh air supply. A gas stove that is not burning clean in a small kitchen that is poorly vented. Improper chimney clearances from obstacles on the roof that will encourage back drafting during a change in wind direction.

Carbon monoxide facts and the dangers should be well known to everyone. Hopefully these tips will help you reduce your risk of CO poisoning.

Testing for carbon monoxide is a standard part of my home inspection.