I am thinking about converting from an oil burning furnace to natural gas. Let me give you some history: We live in Connecticut. The house is circa 1929. Present furnace is 26 years old. Radiators are the old cast iron water filled type. Two story (not including the unheated cellar or attic) colonial house, exterior is brick on first level & steel siding on second level. After doing some calculations based on the previous year, I estimate will be be filling the oil tank at least once a month during the heating season. At a cost of apprx $1000- yikes!!! I have had 2 plumbing contractors look at the situation and am getting differing opinions. I'm quite confused. Contractor A spent 1 1/2 hrs with me. He recommends a high efficiency unit made in Germany (can I mention the brand?)with the device that measures the outdoor temp. He also suggested venting directly to the outside because our chimney is so old & the possiblity of condensation buildup- or we could have a liner installed at additional cost.
Contractor B spent 15 min with me. Said we probably don't need a chimney liner. Only discussed the direct venting when I brought it up. Recommended a furnace made in NY state. He said the very high efficiency units are not worth the extra $.
I haven't received exact estimates from either contractors yet but it sounds as if contractor A will be more expensive. He does have a reputaion as being more expensive for general plumbing jobs.

Can anyone give me advice?
Thank you