I moved into a 900 sq ft house last year located in upstate NY that has a crown keystone km100 boiler. I can't find any information on it but from what I can tell is relatively new. I would like to bring natural gas into the house to replace a 20 year old electric hot water tank and am thinking of replacing the the boiler with a high efficiency natural gas boiler. I am partly doing this for the high cost of fuel. Do you think replacing this relatively new boiler is foolish? I used roughly 500 gallons of oil last year and figure my cost savings with natural gas would be pretty substantial. I had a few quotes and the ones I had recommended are a Buderus gb142 and a Dunkirk q90. do you think I should go with a modulating one? I know with the Dunkirk they can install an optional modulator, would that be sufficient? What does a modulating condenser get me? I am also going to install an indirect water heater. Do you think a tank less system would be better?