My Aprilaire 600 unit is making a very loud noise when starting up injunction with the furnace starting up. After taking the water pad off and watching the start of the furnace, the water came rushing out of the copper tubing and thats when the noise started strong and weakened within 5 seconds. The noise is most certainly coming from this rush of water to the copper tubing which drips into the trough leading to the water pad. I am lost on why this noise (coinciding with the rush of water described above) is happening and what I should do to prevent this noise from taking place. It can be heard from the basemant all the way to the second story of our house. Any help would be appreciated. Thanks.