Responding to Mike's question ....
The CO laws are introduced with good intentions. It is ironic that one of the primary causes of CO in the house these days is the direct result of other well-intentioned requlations. Indeed, these 'unexpected consequences' are one reason I am so adamant about restricting the role of regulation in our lives.
In the late '70's, the 'energy crisis' led to folks taking extreme measures to seal their homes in an effort to reduce their heating bills. This emphasis is carried on today in the latest spate of 'energy' regulations ("cash for caulkers") and the LEED program. There are even firms that pressure-test buildings for leaks.
The caulking madness of the '70's was followed by the 'toxic mold' issue of the '80's. This led to a renewed emphasis on bath fans, kitchen exhaust fans, and such. The "Mechanical" code upped it's requirements for exhaust air.
Does anyone see the problem yet?
When you try to pull air out of a sealed house, you create a vacuum. This in turn results in the flow from your various flue pipes to reverse. In order for the fresh air to enter, first the exhaust gasses have to be pulled into the house. Voila! CO problems.
How bad can this be? I've seen one job where this back-draft was strong enough to prevent a commercial gas water heater from fully igniting, even though the flue was both large and straight- and this was with a fully open door between the water heater and the exhaust fan! In this instance, the 'exhaust fan' was the air conditioning system.
So, Mike ... consider that under today's construction practices you can have a CO problem precisely because everything is working 'right.' With the current political emphasis on sealing your home, expect the problem to worsen.
