[stevehull]

AC,

Please note that I am not against all gas appliances. But they must be put in properly. I really like vented water heaters in the garage - not in the home. And I never ever recommend the use of spot combustion heaters - even if they say "ventless".

I also put a return plenum in the kitchen to my HRV when I designed my other home some ~20 years ago. It was on low speed 24x7 (20 cfm). Above the propane fired cooktop, we had the required direct vented hood. I also adjusted the HRV fans so that the HRV allowed a very small positive pressure in the house (0.2 inch of water column).

This not only kept out dust, but helped to rid the kitchen of any combustion gas issues.

I measured CO2 in that house many, many times and at the highest it ever got to 425 ppm.

Also note that the pilot light in many gas stoves produce a huge amount of CO2 over 24 hours.

Now I am beginning to better understand your home CO2 issues.


Steve