When writing answers to readers or reports for clients, I often abbreviate the term for heating, venting and air conditioning down to HVAC. But it appears most people only think of the heating or the air conditioning portion of the reports and ignore venting, the most important part of an HVAC technician's job.
An improperly vented fossil fuel burning appliance can be deadly. The byproducts of combustion are carbon monoxide gas as well as other unpleasant gases and moisture. Carbon monoxide is colorless, odorless and tasteless, but when the concentration is greater than 100 parts per million (100 ppm), it becomes toxic by combining with the body's hemoglobin to form carboxyhemoglobin in the blood, preventing the hemoglobin from releasing oxygen to the body's tissues.
People exposed to low levels of carbon monoxide poisoning may suffer headaches and dizziness similar to the flu, but when the flulike symptoms continue, it is very important to seek the advice of a doctor or other medical professional. Extended low-level exposure can be toxic to the heart, the nervous system and other vital organs. Exposure to high levels of carbon monoxide is deadly.
Everyone should have at least one carbon monoxide detector in each bedroom and another near the fuel-burning appliance or appliances. When in doubt about where to place a carbon monoxide detector, seek help from your local fire department or health officials.
There are safety codes for installers to follow when venting flue gases, but I have also seen fire hazards caused by other installers' carelessness with range hoods.
If the hood is nonventing or is a recirculating type unit, any experienced technician can install these units. It's when the hood is designed to vent to the exterior that I find problems. Either the venting pipe ends in an attic or the hood vents into a wall cavity. A vented range hood must vent to the exterior all the way through the roof or through a sidewall.
Over time, as the fan is used, grease will be pulled into the flue or cavity where it will accumulate, ready to fuel the first accidental range-top fire, and it will blow like a torch through the wood structures of the home. Also check the clothes dryer vent pipe from either a gas or electric dryer. The clothes dryer pipe must be a smooth-walled metal pipe where possible and vented to the exterior. Lint is highly flammable and fires from dryer vents are estimated to be responsible for more than 100 injuries, five deaths and more than $35 million in damage annually.
C. Dwight Barnett is a certified master inspector with the American Society of Home Inspectors.
HomeStyle on 01/31/2015