Spacing for PVC Pipes Used for Aeration

A common question that I get is regarding the use of perforated PVC piping for aerating their compost pile. The question is, how many do you need in one pile? How should they be spaced?

The answer is that the more air you can bring to your compost, the better! At my test site I usually have pipes stacked vertically with approximately 2-3 feet between each pipe. This seems to work well. I have never experimented with using any more than that so I don't know when is too much. I have seen people use fewer with greater spacing and they do not get the results that I do in terms of the quality of degradation. I would propably not insert any more pipes than I suggest because the pile may have difficulty generating and retaining enough heat.