Hello,

Our 3-1/2 ton Trane XL14i heat pump is located near our bedroom so we get to hear its operation nightly. When the outside temps are about 36 degrees or higher, the hp gives a steady hum which I consider normal operation.

When the temps go down to freezing and below, the hp noise becomes very annoying with a pulsating low frequency hum. Here is a link to a video illustrating the noise:

http://s672.photobucket.com/albums/vv81/DavidPJ09/LJ%20House%20Equipment/?action=view&current=MainHeatPumpNoiseShortVideo010112.mp4

Do you consider this normal hp noise? You'll have to listen carefully to hear the pulsating low frequency hum which didn't come through very loud in the recording. There's also a smaller XL14i right next to it and it always just gives the normal steady hum.

Thanks for your suggestions.