Advice regarding fireplace grate heater

[happymomma]

I am hoping someone would have advice for me. I don't know anything about fireplaces but would love to learn more. Anyways, in our new house, we have a fireplace finally. There's been a huge draft from the flue so that our family room gets pretty cold. So today I went to Lowes and got one of those glass doors for the fireplace. I heard that I can get a fireplace grate heater that will circulate the hot air from the fireplace. But I know nothing about it.

Does anyone else have one of these and which one do you have. Also, if you have one, does it work with any glass door? We just got the glass door from Lowes and I don't want to buy another one.

Thanks.