I have a new York hybrid heat pump/ furnace system. Now in first cold weather snap. Notice that heat pump and furnace are both running simultaneously. I thought the unit was to switch over so that just furnace runs in very cold weather. I gets pretty loud with both units operating. Is this the way it is supposed to be?

Yes they both can run at the same time BUT it really depends upon how it is installed and set up. I would contact your dealer you bought the unit from for any questions on operation since they know your system and we do not.