Humid air and Lennox HEPA 40
In the last few years, we have been experiencing a lot of wildfire smoke in the metro Vancouver region of BC. Because my wife has respiratory issues, we want to install a fresh air delivery system that filters out the PM2.5 particles which affect her. A contractor is suggesting a Lennox HEPA 40 Bypass Air Filtration System that will duct into the cold air return. It will pull in fresh air through the HEPA filter and then duct upstream into the cold air return. There will be a return line further down the cold air return that he will balance. There will be a 5inch fresh air supply duct and the trunk lines will be 8×14. The HEPA 40 supplies 320 cfm.
Will this introduce moisture problems into the house? What will happen to the cool humid air that comes in? Will it condense in the ducts? Saturate the HEPA filter with moisture?
Thank you.
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Replies
Typical fresh air supply to a house is between 60 to 100 CFM. Since your unit is rated at 320CFM, there will be a lot of mixing with house air which will help bring the dewpoint of any humid air down before it even hits the filter. There shouldn't be any condensation.
Do make sure the tech commissions the fresh air supply properly and check fresh air flow rate through the 5" pipe while the air handler on and off.
You might also want to add in an additional damper on the intake that you can close incase of fire season. Filters do help with removing outdoor particulates but are not 100% efficient, sometimes, better to have higher CO2 levels in the house than smoke smells. An activated carbon filter can help a lot with smells but needs to be replaced frequently, it is something I would only add if needed.
Thank you Akos for alleviating my concerns.
Aaron