My Burnham boiler is 38 years old and still works ok but I think it is about time to replace. I am told it's efficiency is only in the 60 percent range. There are so many makes and models so I am looking for guidance. The present boiler is vented to a chimney but I am considering a direct vent in order to make the chimney available for a wood burner. What is better, a condensing or a non-condensing boiler? stainless or cast iron burners? smart controls or standard? how high efficiency should I get? how many BTUs do I need.

My fuel is natural gas. The house is 2 story 2400 square feet with about 16" of fiberglass insulation in the attic. All windows are double pane and most of them also have an outside storm window. I live in northern Ohio.

I prefer to buy made in USA. Because I have had good service from the Burnham I am leaning in that direction. What do you recommend?