"PipeDown" wrote in message
Here is an idea: Take a piece of 4" PVC pipe and use a router to cut a
slit along it wide enough to get the hot water pipe into. Fill the pipe
with expanding foam insulation (or whatever you want) and seal the slit
with mastic or aluminum duct tape and bury slit side down.

Good idea. Use the spray in foam. It gets hard enough and will stay in
position so you'd not have to put the slit down. Sure would give plenty of
insulation.