Our home was built in the mid 1980's and has what is known as a metal fireplace - basically a metal firebox, and metal chimney, with a flue that could be opened and closed and a chain curtain, just like what you are describing. We decided to get a gas insert with an enclosed glass front. (Avalon - they make quite realistic glowing logs and embers.) The model we chose has three flame levels, three fan speeds, and a thermostat feature on the remote that can turn the fire off when the room hits the temperature you preset.

Installation involved running two flexible vent pipes up inside the old chimney pipe - one vents fumes and the other brings air into the firebox. An electrical outlet was installed inside the old firebox, just behind the new gas insert, to power the fan. Total cost ran us about $4000 with tax, plus we splurged on the installation of a slab granite surround (a deal on a remnant) which was another $500 installed.

We made the decision to get the insert after a December windstorm left us without power for four days - brrr! Granted, the fan won't work when the power is out, but it will still put out some decent heat. Since we've had it installed, during the fall and winter we spend nearly every Saturday morning sitting for hours next to the fireplace - nice and cozy! On the low setting, with the fan on low, it keeps us very comfortable; in your situation you probably wouldn't need the fan, since you are not looking for much heat. As for maintenance, in the two years since we've installed it, the only thing I've had to do once or twice a year is clean the inside of the glass (it is removable, with a bit of effort) - despite claims of gas being clean burning, a bit of residue will build up over several months of use.

You have two options. A fireplace insert (gas) which is basically a box inserted into the opening of the fireplace. There is glass in the front. You will have blowers as well to give additional heat. This will be able to fit in your 5K budget. However since you are not looking for heat really this is a very expensive option and probably not your best option. Instead you should just purchase a gas log set. A vented gas log set will have a beautiful flame. You will get heat from it but not with the additional blowers etc and a really nice set will run you about $1200.

I am in the process of researching gas fireplace inserts as well. What I have come to understand is that you want "direct vent". The Mendota is one that we are considering - it has a wide range of heat output and the most realistic looking flame. Another one is the Valor-which has a remote that you set where you sit and the heat regulates to that temperature all the time. Aparently you want ceramic glass, not tempered glass because it is more efficient. I have several other names: marquis Capella, Kozy Heat Chaska, Enviro E20. I have been spending hours looking for reviews and am not having much luck. Most of the reviews are from pre 2010 and I'm sure things have improved since then. Any other experiences???