Looking to replace our ventless fireplace for obvious reasons.. We live in the NE US. Currently we have a propane fireplace and are potentially looking into natural gas. There is a chimney from when there was a wood burning fireplace but not sure of condition. But then we got thinking maybe a pellet stove insert or a wood burning insert stove would be more efficient? And what would be cost effective to install? Please give advice, we aopreciate any suggestions and thanks for your help!