Presuming you are talking about the vents sold for side walls, with shutters that open as the fan turns on, as opposed to the round type used on roof tops; if it fits the space and the amount of air you need to exhaust, I can't see why it wouldn't work.

However, it may rust out pretty quickly. A friend with large commercial GHs saw the big exhaust fans in our hay loft and when she learned what they had cost, decided to save some money with the same kind in one of her big growing houses.

They did move a lot of air, but not being made to withstand the continual moisture; didn't last more than a few years.

Most attic fans do NOT have a shutter on them. In cold weather it will draw your heat out through the hole by convection even if the fan is not running.
Generally speaking a product that is designed to do a specific job it will preform much better and longer than trying to use something that was not designed for that type of use.

I have the lowes fan in my HFGH. This will be its 3rd year and is holding up well. I have the 6x8 and use the fan to help move the extreme hot air build up in summer.

Thanks for the responses. Hadn't thought about the venting of hot air in the winter.

Thanks

Are we talking about the same types of exhaust fans here?

There are roof fans used to exhaust low ceiling attics through the roof. Those have mushroom caps and indeed; no shutters, and those for vertical wall installation, that do have shutters, that open only when the fan is running.

May we presume this thread is in reference to the wall type?

Actually, I was talking about the mushroom roof type. Couldn't it be blocked off with a piece of cardboard in the winter?

Well it could be blocked off in the winter, but then if it gets sunny you've taken a perfectly good automated system and turned it into a manual one. You'd have to open something to get venting then on a sunny day. You think, well I could do that. But then here's what happens: you go to church or somewhere where you can't leave. It's cloudy so you leave it closed. It gets sunny while youre gone and everything cooks. Or the other way around, its sunny and so you vent it open. A cold front comes in and the temps drop 30 degrees. Your heat kicks on with the vent open and you lose 30% of your propane tank heating outside.
Now don't you wish you'd just gotten the proper equipment to start with?
been there done that! LOL

sandy is right troykid.

Buy the right equipment, designed for the purpose, and in the end, you will spend less time, money and effort on equipment that doesn't do the job for you, and have all that much more to spend enjoying your GH.