80,000 BTU 2-Stage Gas Furnace vs 66,000 BTU Low NOx Modulating Gas Furnace 98%

Both furnaces deliver about 64,000 BTU of output, so the real choice is efficiency versus simplicity. The 98% modulating furnace (B) uses far less gas over its life, runs quieter and steadier, and vents through PVC sidewalls, but it needs a matching two-pipe vent system and costs more up front. The 80% two-stage furnace (A) is the practical pick where a chimney or existing metal flue is available, where budget matters, or where a communicating Comfortbridge system is already in place. Owners of modulating units consistently report more even heat and less cycling; two-stage owners value the simpler install and cheaper service parts.

• Choose the 80,000 BTU two-stage furnace if you have a chimney or existing flue, want the lower installed cost, or are pairing it with a Comfortbridge communicating system.
• Choose the 66,000 BTU modulating furnace if you want the highest efficiency, the most even heat, Low NOx compliance, and can run PVC intake and exhaust pipe.