Which exhaust fan can be installed in a hood with a cross section of 20 by 20 cm?

Good afternoon, Alexander. The maximum power corresponding to the size of 20 * 20 cm.

There are two options:

1. Ducted, you can study in detail in this article.
2. Conventional exhaust fans. Rating of the best presented to date here.

You must understand the reason for the occurrence of high humidity, this will not save. There may be two causes.

1. The integrity or technology of the blind area is violated. It is necessary to go around the perimeter of the house and carefully inspect for the presence of sagging soil. The problem place, the correct dimensions of the blind area are shown in Figure 1.

2. The integrity or technology of waterproofing the foundation has been violated. Pay attention to the presence of wet spots on the walls of the basement. If detected, you will have to dismantle the blind area and open the foundation to restore a single layer of waterproofing.

If the waterproofing was carried out by roll material (roofing material), the integrity may be violated at any point on the foundation. The place of the wet wall surface in the basement does not mean that the integrity of the waterproofing is violated in this very place on the reverse side. For clarity, Figure 2. Most likely, it will be necessary to excavate almost the entire perimeter. If the waterproofing is made with bituminous mastic or liquid rubber, the integrity is violated strictly at the same point from the back.

In fact, the problem is very serious. If the concrete is in constant contact with water, this leads to its rapid destruction. Do not forget, inside the foundation there is armature, from contact with water, the corrosion process begins. As a result, its volume inside the concrete increases in the literal sense of the word, breaking it.