We’re in Barrington and did this a few years ago. We had oil but needed to replace the boiler, so converted to gas.

You’ll need to hire a plumber before you can submit your paperwork. (At least this is how it worked before RI Energy took over.) A big part of the cost is what boiler you choose. We went with Viessmann. Call around and see what different plumbers would charge you for the boiler and the inside work.

We had gas in the street so hooking us up and providing the meter was free; I think being free depends on your distance from the street. Funny enough, National Grid told us we didn’t have gas in the street; it was our neighbor who told us we did, because he paid to extend the line!