It seems like my OD pedal and the delay don't like being daisy chained together. Removing one or the other seems to get rid of the noise. My reverb pedal seems to play nicely with others.

My wife is running our washing machine in the other room. It's supposed to be one of those high efficiency ones. I get pulses of noise as the basket moves in it. And I've got a fluorescent light in my office. And my computer. And a fridge and freezer in the next room. And my furnace. Lots of potential for noise. Any further questions as to why I like noiseless single coils?