Dripping noise from all-in-one unit when heat is on

I have one of those all in one closet units in my apartment that has the hvac stacked on top of the hot water unit. I noticed starting today that when the heat turns on there is a loud constant dripping noisie coming from the closet. It stops as soon as the heat turns off. I can’t tell if it’s from the hvac or hot water. I’m assuming the hvac since it stops when the heat turns off. Seems to be in the pipes below the hvac or possibly in the unit itself but it’s really hard to tell.

There are no leaks I can see, and no water dripping through the coils or anything weird like that. I have hot water so no issues there either.

What could this possibly be? Should I be concerned? It makes no sense to me and I’ve never heard it before that I can remember.

Thanks for any help

source https://hvac-talk.com/vbb/threads/2235740-Dripping-noise-from-all-in-one-unit-when-heat-is-on?goto=newpost