Sora09199- In case you haven't found a Fireplace code yet, here it is:
Tell Nook:
TqkckitsbecadY
TpinkitsbecayG
It's worked every time for me and I even have a few extras, from towns I've destroyed. So, if for some reason it doesn't work, let me know and I can send you...oh wait! You can't send rare stuff by code, as far as I know!
The only other way to get one is to go to Jan. or Feb.(?) and visit an igloo. It should to be one of the nice females, like Bessie, who will tell you she has "Five items I want to sell you". She lists them off and you just hold out for the rare ones, like the tent model, igloo model, snowy tree, snowboard, sleigh and chowder...and finally, the fireplace. Of course, it could take awhile, since they don't always have something rare. Some other animals can give these to you but it's less likely.
Speaking of chowder, here's the code, since nothing looks better warming up on your fireplace!
ii9GES@sTRJhAA
sh09cb39UaKHL4
Let me know if it doesn't work and I'll check again...but I'm pretty sure these are correct. Good luck!