[bobhalford]

I would call down because he could be doing this with a flush draw with the K [img]/images/graemlins/heart.gif[/img] or Q [img]/images/graemlins/heart.gif[/img], trying to scare you into folding in case you don't have the Ace. He may even have worse than that and trying to scare you. Definitely strange, because once you call the turn you are committed to calling the river, which costs 2BB if he has the A, a flush, or hits the flush on the river (provided you call on a 4 heart board).

The donkbet could also mean that he's got the flush, thinks you have the Ace, and is hoping you will raise so he can go to war with his flush.

But since he is a bad player, it's difficult to know what anything means. His AF is 1.6, so I would just call down and hope you are good. Raising the turn risks a 3-bet, so maybe it's a WA/WB situation and you need to call. If I were to fold here I would feel kind of bad, raising feels like spewing (or really smart) and calling feels about right. He may check a non-heart river and you will be good some of the time, especially if a K or J hit, and other times you will be good UI.