HVAC Air Filtering?

[Alex2305]

I was told by a HVAC service tech the incoming fresh air does not pass thru the air filter, only the recirculated air is filtered. I don't see how this can be since I only see one incoming air conduit to the HVAC unit passing thru the filter before entering the unit proper. Did I misunderstand the service tech? TIA Alex

 

[oldognewtrick]

Do you have a vent that allows for outside air to enter your system?

 

[Alex2305]

Do you have a vent that allows for outside air to enter your system?

Yes. It is on the roof of a mutli-tenant condo building where the compressor is. I also have another condo that has an integrated wall unit so it draws air in directly to it.

 

[beachboui]

Believe what your eyes tell you. If you have a closed ventilation system and the unit is only drawing air from the outside, it is only drawing fresh air. If, on the other hand, the air handler is open to the interior, it is recycling the interior air. This is more efficient than heating or cooling outside air. Outside air would only be necessary if the building is very "tight", meaning very little air leakage into or out of the living quarters.

 

[pjones]

I’ve seen roof top units installed with a factory optional fresh air supply that bypasses all filtration. Stuff like that is not common but it happens. If you don’t trust that tech then get a second opinion from a different company and see why they have to say.

Every system is different. Typically, as a rule of thumb, fresh air is filtered as it gets pulled in through the air handler, but to every rule there is an exception...