Many states have adopted NFPA (National Fire Protection Association) rules as their regulations for fire protection. Under NFPA rules, any new boiler installation must be made into a properly lined chimney.  Wood pellet boilers are not an exception.  If your chimney is already ceramic or steel lined, there will be no need for further lining; however, if your chimney is currently unlined, as many are, you'll need to have the chimney lined.  Steel lining of typical chimneys costs around $1,200.

Maine regulators have interpreted State laws and regulations to allow for the placement of a pellet boiler in a common, properly lined, chimney with an oil boiler if the pellet boiler manufacturer's installation instructions allow for that configuration.  The MESys boiler manuals contain the following chimney installation instructions:

"* A pellet fired boiler and an oil boiler can be flued only individually in to an existing chimney providing the following conditions are met: 1) Electrical interlocks are in place to prevent simultaneous operations. 2.) A mechanical lock-out device must also be in place to prevent simultaneous operations. 3.) At any given time, only one boiler can be vented into the chimney flue. Allow either boiler to completely shut down and cool off before changing the venting system. 4.) The flue must be of adequate size to handle the combustion products of either appliance."

Because there is a small amount of ash in the exhaust of this boiler powerventing is not recommended.