Recommendations for gravity furnace replacement

[Zacha341]

I live in a property having two huge octopi heat rise furnaces with all the piping and tubing. It took the contractor two days to 'beat' that stuff out -- flattening it down to pulp and hauling them away! Then came the centipedes and spiders for a month, apparently awaken from all the disassembly noise it seemed.

Instant 60% reduction of gas bill when replacement units were installed. There's little nostalgia IMO in old heating. Only a huge bill!