I saw a post the other day about wrapping plumbing pipes with the black foam pipe insulation. It got me thinking about how beneficial that was in the grand scheme of things...
Premise: Pipes in a basement that aren't at risk of freezing in the winter. They are for plumbing, not heating the floors or radiators. Is it worth insulating the hot or cold lines?
Situation #1 is that if you wrap the hot lines and you run the hot water somewhere for a minute and then turn it off, the pipes will be full of hot water. Without insulation, I think the water will cool off noticeably in 10 minutes. With insulation the water will cool off noticeably in 30 minutes. Assuming that's correct, how often are you running hot water in the same part of the house within that 20 minute window where it saves water?
Situation #2 is that you like really cold drinking water. You run the sink and get a cold glass of water. The cold water line leading to the sink is now full of 45 degree water (maybe warmer if it's summer). I'm guessing it will heat up halfway to basement temperature in 10 minutes if uninsulated and 30 minutes if insulated. So again, how often are you needing colder water and your need lines up with that 20 minute window where the insulation helped?
Situation #3 is that you're trying to just save heat. Since the heat bleeds through the insulation anyway, the energy you put into that hot water is still, eventually, leaking into the basement. Unless you happen to turn that hot water faucet on during that 20 minutes.
I could be wrong on the 20 minute improvement in heat storage, maybe it's longer? It also could be that by adding the insulation you can turn the shower temperature down a little bit since the hot water getting to the shower is a bit hotter with the insulation on it.
I'm pretty sure the manufacturing of the black foam pipe insulation isn't great for the environment.
Does anyone have more scientific input on if it's worth insulating hot, cold or both types of pipes in a normal basement?