Healbomb Damage Limit?

[Zerrif]

I'm not sure if one exists, but let me explain the situation.

I healbomb ED's for 4032 damage with my gears. Recently, I switched out a Frigg's Circlet for a Maiden's Hat (5% more heal), and it heals me for more, but doesn't inflict anymore healbomb damage.

I took off the hat and put it on, and no change in damage. So my question is this: Is there a limit to the damage healbombing can do? Or does Maiden's Hat just not affect it (which it should, considering the description says increases effectiveness of Heal by 5%-- whereas Staff of Recovery reads very similar and DOES affect healbombing, but instead of 5%, it reads by refine rate)?