First, the fresh air system itself is to replace the air inside and outside the house. When it runs, the formaldehyde in the house will be discharged side by side with the replaced air, which can reduce the concentration of formaldehyde in the house. So I think the fresh air system can provide some help from in addition to formaldehyde in principle.
Some people may worry that if formaldehyde is just discharged, but immediately absorbed by the fresh air system, isn't it equally ineffective? You don't have to worry about that. The filter screen of the fresh air system contains activated carbon, which can well filter out impurities in the air and make the air entering the house fresher.
In addition, I personally think it is good to install a fresh air system at home, especially in some cities with poor air quality. Installing fresh air system can effectively improve the air environment at home and make yourself live better at home. But personally, I think it is a little difficult to completely remove formaldehyde by fresh air system. Although it can effectively replace the indoor air, formaldehyde itself swims in the air, and it is impossible to directly pump away all the indoor air and completely replace it. So there will still be some residual air in the house.
If you want to completely remove formaldehyde, you should start with decoration materials and buy some environmentally friendly building materials. This is the best way to solve the problem. Other methods can only be reduced, but not completely eliminated.