Lennox Pulse Furnace

[Bruce L. Treacy]

Please explain the reason behind the following: the vibration material used to separate the plenum and the furnace, secondly, the enlarged 4 " diameter baffle on the exhaust vent.

[Gordon I. Kay]

The vibration material used on the plenum is to help reduce noise transmission through the duct work, there should be one on the return air duct drop as well. A stainless steel flexible gas line is also used on the pulse for the same reason
The enlarged 4" diameter baffle is a muffler, again to help reduce noise. Some units would have them on both the exhaust vent and the intake vent.