On 2007-04-30, Owain wrote:

Get a big 8" or 10" through-the-wall fan from Xpelair or VentAxia,
designed for commercial use and priced accordingly. They should run 12
hours a day for years and be almost inaudible (except for when the
backdraught shutter snaps shut).

Is it possible to get a high-quality one with a small diameter (around
4")?

The front air brick is flush with the front of the house but recessed
(when you look at it from inside the cellar) in a hole just bigger
than two bricks --- so I want to mount the fan in a board, screw the
board to the wall over the hole, and probably caulk around it.