On February 2, 2003, Monica Bhasin called in sick to work.  Two days later both she and her two children were discovered dead in their home from carbon monoxide poisoning.  We performed an investigation and determined that several factors lead to these tragic deaths.

First, the carbon monoxide came from a William gas-fired gravity-vented wall furnace.

Second, the header plate for the furnace was improperly installed.  This caused the exhaust vent to partially block the top of the furnace.  This caused the exhaust from the furnace to back-flow into the house; this also caused the furnace to produce high levels of carbon monoxide in its exhaust.

Third, the furnace did not have a “vent safety switch” that would have detected the back flow from a blocked exhaust vent as required by ANSI Z21.49b-1988.  The furnace manufacturer claimed that they made the furnace after the standard was adopted but within the unofficial grace period stated by the standards committee that allowed manufacturers to discontinue existing non-compliant product lines even though Williams own engineers were on this committee and would have known of the requirement for a vent safety switch.

Fourth, the exhaust vent might have been further dislodged due to its lack of connection to the header plate when the roof was replaced.  This might have further blocked the exhaust from the furnace.

Fifth, when PG&E inspected the furnace, they did not notice that the furnace exhaust was blocked and that the exhaust from the furnace was flowing back into the room.