Venting IN through a chimney?

I've seen a lot of accounts of chimneys making a good output exhaust but was wondering if anyone has used it for cool/fresh air INTAKE?

My flue isn't used at all (fires / gas boiler) and I can feel the air in my fireplace is noticably cooler, so it makes sense to me.

Obviously I'll want something to filter out any dirt up there but are there any other pitfalls?

I guess if you got a good filter it could work. You can get a good hepa filter for like 80 bucks. Id leave a thermometer in there in the summer and make sure it doesn't get hot. But they do make a good exhaust.

I can't think of any reason you couldn't use it long as you get a good filter. You defonately don't want all that ash and soot blowing all over your plants.

I buy a heap filter sounds like a decent idea think exhausting through it is better though

Muckelby a chemney by design is an exhaust and if the wind is blowing outside it will draw the inside air harder. The reason the air is cooler at your fireplace is because the air is constantly moving if the flue is open. Just my 2 cents i would rather use it as an exhaust....

even seen a chimney with a whirly bird on top of it free fan . works great.

that's a good point dsnutts, will probably go with a stealthy window venting system, less potential problems to so long as I do a good disguise job...