The projected savings of using pellets depends on your location and the projected efficiency of the boiler.

Efficiency gets measured in comparative terms of British Thermal Units.

How many BTU do the wood pellets create versus how many BTU would the oil create?

What is the current cost of the pellets and what is the current cost of home heating oil in your area.

Local big box retailers, for example, might sell a ton of wood pellets for less than $250.

Home heating oil can sell for anywhere from $3 to $4 depending on the location and time of year.

Comparing the fuel costs per average year will also help you determine how long it might take to recoup any extra cost associated with a pellet boiler versus oil burner.

In some circumstances, pellets are considerably less expensive to use than oil. Just depends

Here is a link that might be useful: http://greenhomeandgarden.net