Chapter 6 Heating System Safety Tests National Oilheat Research Alliance 41 Home performance contractors are required by the Building Performance Institute (BPI) to perform preliminary and post-installation safety inspections of all combustion appliances whenever changes are made to the building envelope and/or heating system. The Safety Inspection includes a carbon monoxide test, then the following three tests to determine whether combustion appliances are venting properly: • Spillage • Draft • Worst-case depressurization of the combustion appliance zone (CAZ). The CAZ is the room containing the boiler, furnace, or water heater. Trained heating technicians must act upon combustion safety test results appropriately. Carbon Monoxide Carbon monoxide (CO) originates from incompletely burned carbon. It is dangerous because it prevents the absorption of oxygen into the blood stream. Causes of CO formation are: • Fuel-rich mixture • Improper venting • Premature cooling of the flame. Sources of carbon monoxide are unvented kerosene and gas space heaters, leaking chimneys, furnaces, boilers, woodstoves, pellet stoves, fireplaces, gas stoves, dryers, other gas-powered equipment, an attached garage, candles, and smoking. Carbon Monoxide Test Carbon Monoxide is measured in parts per million (ppm). Most carbon monoxide test equipment calculates as measured and air free CO levels. For BPI testing energy auditors use as measured values. Home performance contractors measure ambient CO levels (ambient means the air in the room). BPI certification requirements state that ambient CO shall be monitored upon entering the CAZ and during the test period for all appliances. An ambient reading over 35 ppm is considered unsafe and requires action. They also measure CO in undiluted flue gases (the gases present in the heat exchanger before the draft relief air from the draft regulator is blended with them). The reading for the undiluted flue gases at steady state should not be higher than 100 ppm. Unvented and “vent free” appliances are not recommended. BPI tells contractors to not test them. (You touch it. You own it.) Home Performance contractors are instructed to stop the audit as soon as they discover an unvented appliance and to tell the customer it is dangerous and should be removed. They will return to finish the audit once the appliance has been removed. CO and Oil Burners: Combustion Air Supply Problems An oil burner’s CO production can increase dramatically with incomplete combustion which can result from either insufficient combustion air or too much combustion air. Insufficient air will also create smoke, while too much air does not, but excessive air will create a yellow spot on the smoke test paper from unburned oil. Because one of the major causes of CO events is insufficient combustion air in the
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