[ac29]

> Water in pipes inside a house's "thermal envelope" is presumably around 72 deg. F.

The pipes in my house are in the crawlspace underneath the house, which is definitely nothing like 72F this time of year. Any hot water more than 10 feet or so away from the water heater runs pretty cold for several gallons.

[Digory]

That sounds like a good weekend project, putting split foam insulation around your pipes. 8' runs are a couple of bucks at the big box stores.

It's not quite as efficient, but I put in a recirculation pump and a timer to keep the water warm throughout the pipe during the day. The clothes washer was never getting warm water, and we wasted a lot at the shower waiting for warm water to reach it.