Yes you can use that for fans. It's way overkill, but as long as your fans aren't drawing over 10 A you're set. Are you using a uC to control the relays? If so, you could just use a 2N2222 transistor switch for small PC size fans, or a MOSFET, either of which would be cheaper and have a smaller footprint.
The power to tax, once conceded, has no limits; it contains until it destroys. I was not joking when I told them to dig into their own pouches. It may not be possible to do away with government — sometimes I think that government is an inescapable disease of human beings. But it may be possible to keep it small and starved and inoffensive — and can you think of a better way than by requiring the governors themselves to pay the costs of their antisocial hobby?
R. A. Heinlein