Heating meatballs in pasta sauce I made meatballs yesterday in the oven and I'm going to add them to pasta sauce tonight to heat them up and add them to spaghetti. My question is how long should I boil the meatballs for in the sauce before adding it to the pasta and serving. 

The recipe I was looking at didn't use the oven so they cooked the meatballs in the sauce for 20 minutes without stirring and then another 20 minutes while stirring. So I would assume I just have to boil the meatballs long enough to heat the sauce and the meatballs. However contrary to this while looking up how long I should cook the meatballs for I came across one recipe that cooked the meatballs in the oven and then cooked them in the pasta for one hour even though the meatballs were already cooked.

So my question is how long should I cook the meatballs in the sauce? What are the benefits to cooking them for a longer or shorter time? Can you cook them for too long and if so what is too long?
20 or so minutes cooking the meatballs in the sauce has always done the job for me. You want to cook them sufficiently long so that they absorb the moisture and flavour of the sauce, but not too long such that they lose their firm texture. The reverse process of the meat flavouring the sauce is also an important one.

As a side note, it is more advisable to simmer the sauce, rather than boil it, or it will likely become too thick and may even burn.

In general, the combination of initially cooking the meatballs in the oven, and then simmering in the pan is the right way to do things. This ensures that the meatballs are sufficiently cooked, do not fall apart, and have the right firmness. Worth noting is that you should pad off the grease on the meatballs before putting them in the sauce.