Originally Posted by
Chlau
How do you know that your mechanical fresh air system is working properly? We moved into a new home and when we turn it on, only one bathroom fan comes on, and there is very little air coming through the vents.
There are air flow hoods that accurately measure air flow from inlets/outlets.
More generally, observing indoor dew points verses outdoor dew points and adding the moisture from the occupants indicates the amount of fresh air entering the home. With two occupants, a 10^F rise of the indoor dew point above the outdoor dew indicates 60 cfm of fresh air entering the home.
Monitoring the indoor CO2 levels verses outdoor dew points and the number of occupants inside will also indicate the amount of fresh air entering the home. Two occupants in a home with a 700 ppm CO2 level would indicate 60-80 cfm of fresh air entering the home.
A home should have an air change in 4-5 hours when occupied to purge indoor pollutants and renew oxygen. A 2,500 sqft. home should have a minimum of 75 cfm of fresh air when occupied.
Regards TB
Bear Rules: Keep our home <50% RH summer, controls mites/mold and very comfortable.
Provide 60-100 cfm of fresh air when occupied to purge indoor pollutants and keep window dry during cold weather. T-stat setup/setback +8 hrs. saves energy
Use +Merv 10 air filter. -Don't forget the "Golden Rule"