Heat Pumps and Electric Heating - Humidity never seems to get high enough

We have a carrier infinity heat-pump and A/C system. Got an AprilAire 600 humidifier as part of the system.

But during all seasons the internal humidity never seems to get high enough, the winter months are worse. Humidity seems to hang around the low 40% area and cannot get it higher then that.

On the carrier infinity control panel, I have the setting on high but do not think it really makes a difference what I set it at. The actual humidity is always below what the target humidity is set at. And the max setting according to the system is like 45%, is that normal?

Are there things I should be looking at? DO I have any options or ways to try and increase the humidity? It is a new system, put in maybe 5 or 6 months ago.

Thanks

In the winter heating, you won't want the humdity to be any higher than 40%.. Otherwise will have water vapers on windows and other cold spots..

Also on a heat pump system. you don't have a high heat out put, so it only going to put out soo much humidity.. If you really need more, is the water line on the hot side?

yes the water in line is hot water. The more and more I am reading, the 40% range seems to be the norm.

I am surprised though how much it can fluctuate from day to day, guess it all depends on whats going on outside.

Thanks