Death by Carbon Monoxiide

[Gary Reecher]

Depends upon the size of the crack and the location. Even though the inducer generates a negative pressure to move the combustion gases through the heat exchanger passages the farther away from the inducer the less negative pressure is developed. Up by the burner flame if one were to test the negative pressure may be half of what is available at the inducer. The other aspect that must be remembered is that even though the air circulator blower is generating a positive pressure in the heat exchanger area which can vary from + 0.2 inch water column and up that the air is flowing acrossed curved surfaces of the heat exchanger. These curved surfaces can do wierd things to airflow.

I have a set of video tapes made by SMACNA (Sheet Metal Airconditioning Contractors North America. They made a plastic duct system where different types of duct takeoffs could be attached to the trunk duct. The blower system was a variabe speed system with a soap bubble generator that injects helium in the soap bubbles. One of the takeoffs showed that some of the bubbles would enter the supply duct from the trunk duct and would reverse and go back into the trunk duct leaving very little air flow going down the supply duct. So air flow in a system can do some very strange things.