> Alas, a Gas Furnace is like 90% efficient (10% of the heat escapes in the steam / waste products that needs to be pushed out the chimney, but everything else

> Alas, a Gas Furnace is like 90% efficient (10% of the heat escapes in the steam / waste products that needs to be pushed out the chimney, but everything else turns into home heating). And there exists even more efficient options today. Like high efficiency furnaces that use the heat from the flue in a second heat exchanger to bring it closer to 99%