I have the same issue. I don't think there is a control for a flue for me though as it's only gas and not wood capable. The fireplace is a heatilator. I feel the cold air rushing in all the time.

I hear ya.

We have the same problem with our glass doors. My solution, although not attractive, was to cover the opening/glass doors with a towel and electrical tape. It helps a lot and I just remove it when we're having company. Have you hear about a fireplace balloon? It looks like an interesting product.

http://www.amazon.com/Fireplace-Chimney-Balloon-Large-Pillow/dp/B0001HA8MC

Nice idea, but is it UCL (and in Canada CSA) approved?

Seems counter intuitive to stick flammable material up a chimney. I suppose it'd be OK if there is only one flue and only one fireplace. But if the fireplace flue hooks up to a chimney where there are other flues, for example the central heating or another fireplace, then I think this type of gadget could cause more problems than it could solve.

Just a thought.

We put a few of these chimney balloons in fireplaces that we don't use much. These 2 fireplaces use the same chimney structure but have separate flues. In my dealing with building codes that is the way they are suppose to be. You cant have two devices sharing one flue. (i.e. water heater sharing fireplace flue) at least you shouldn't have this type of setup anyway or it could backdraft fumes into the house.

The idea with the balloon was to stop the cold like what you guys are talking about, and they did that. The direction said if you light a fire under the balloon on accident, it will pop and fall out.

We did have these flues stuffed with fiberglass but that didn't work well to seal them because they were still cold with fiberglass in there.

Here is a link that might be useful: chimney balloon damper