Tell me about it. I'm having my furnace replaced today to the tune of $7200.00 after discovering two weeks ago that it was blowing carbon monoxide throughout the house due to the problem you mention. Awoken early in the morning with the detectors going off. I would hate to think what would have happened had we no detectors. I have young children. I just don't trust any indoor combustion anymore. Even with adequate air exchange, the gas you do breathe is still poisonous, binding with your hemoglobin and rendering it incapable of carrying oxygen to your brain. I've been sleeping every night for two weeks with 20ppm in the air, hoping that the detectors were functioning flawlessly. Glad this is finally getting fixed.