QuestionsCategory: QuestionsHeat pump vs gas furnace return air vent noise
Handyman Staff asked 2 months ago

I'm in Seattle and considering to replace my old single stage gas furnace (88k BTU output) with either these two options.

  1. Heat pump + gas furnace hybrid
  2. AC + gas furnace

The primary concern is about the noise from the return air vent as it's fairly loud already. Some of your may suggest a larger return vent and properly sized ducts, which I completely agree with, but just for the sake of discussion and for my understanding of the workings of the heat pump, let's assume no changes to the existing duct and return vents, I wonder if moving to option 1 would make the noise (only consider the return air vent noise) worse as the heat pump will be running longer period of time?

Let's use an example from the past data from my Nest: for a 6-hour window at about 37F outside and 68F indoor, the old gas furnace was on for 50% of the time. If I had a 3T cold climate heat pump (looking at Bryant 38MURA High Heat currently) producing ~40k BTU (I was looking at this data sheet, page 56 assuming lowest CFM at 37F, it's 38596 BTU. Let me know if I used the wrong data, but for this hypothetically run time calculation purpose, it doesn't really matter and let's still assume the heat pump I got can produce 40k BTU at that temperature), does that mean it will be on at 100% power for the entire 6 hours?