Had a new bryant heat pump installed(along with new gas furnace) in Dec. This past weekend was the first time we have had realy cold temps and I have noticed that HP was a lot noisier than it had been in the past. It obviously is still working since it kept the house at 70 when outside temp was in upper teens to low 20's (wind chill in single digits). Should I be concerned with the extra noise? Any ideas what might be causing extra noise?