I have an American Standard Arcoliner W 0 551. Recently the oil tank sprang a leak and I want to know if I can convert this model to natural gas, since my hot water tank (a few feet away) is gas fueled.
A gas conversion burner would be a simple means to convert the boiler to gas. It won't be anywhere near as efficient as a new gas-fired boiler. Sometimes you can lease a gas conversion burner from your gas utility.
If all you now have running on gas is your domestic water heater it is quite possible that you would need new (larger) gas piping run from the gas meter to the boiler area.