The answers appear to be “YES”,” MAYBE’ and “NO”  at least here in Maine. 

Current Maine Legislation states that, in Maine, one may under certain circumstances install a solid fuel  (wood or pellet burning) appliance on an existing chimney flue that is already venting the oil furnace. 

The Legislation is known as the “An Act to Permit the Use of the Common Flue for Oil and Solid Fuel Burning Equipment” and it was passed in 2009. This writer could find no further updates on that bill that would disallow the practice. 

The bill stipulates that the chimney must have adequate draft for both appliances; the chimney must be sound, clean and be properly lined. The home and chimney must have a construction date that is older than 1998 and that carbon monoxide detectors must be installed near all bedrooms. 

All this being said, it appears that few, if any, insurance underwriters, have acknowledged this change and so homeowners may find it difficult, if not impossible, to obtain Homeowner’s Insurance. 

For more information, follow the links: 

http://www.maine.gov/dps/fmo/documents/FMONwsltrV2Is3.pdf 

http://www.mainelegislature.org/legis/bills/bills_125th/billpdfs/HP021701.pdf 

http://biomassmagazine.com/articles/5900/maine-removes-a-roadblock-to-pellet-heating-systems/

 http://www.dailybulldog.com/db/happenings/attention-homeowners-new-chimney-rules-in-effect/