I installed the same Honeywell unit on my house A/C. The unit is mounted in my garage as the fan coil is in my attic. It is connected via a rubber hose maybe 8' long. I hear no banging or noises from my inside the house. The unit does click to open the valve to allow water in, make a noise from the boiling water and also when it automatically cleans to purge the water. I suspect kippieland, your unit is directly mounted on your ductwork, maybe in your basement. Have a check on the mounting screws to see if they have loosened or maybe install rubber mounts. I suspect the noises you are hearing are normal from the unit, but you should be able to quieten it down or find why it is making more noise this year, maybe the 40% setting increase is the reason. It does make a noise like a boiling kettle when it is on.
I have my unit attached to my a/c controller which has a humistat setting. It has an automatic mode for humidifying which uses an outside temp sensor to adjust the humidity level. At lower temps it lowers the level at which the humidifer turns on at. This is so you do not get condensation on your windows and mold. So depending on your outside temperature even 40% may be too low. At times my unit is providing 45%. When I recently cleaned my unit I was surprised at the amount of buildup inside the unit. My house water is filtered plus I use the units water filter. My unit is in use a lot but it does make my house more confortable and stops the horrible creaking noises we were always getting from the house in the winter.
