Both my Rinnai HW Heaters have been frozen for 3 days. We're in DFW, and this weather is an every-ten-years kind of event, so we didn't have any issues last year, our first with these HW heaters. Looks like the pipes are frozen inside the walls, and to properly insulate them we're going to have to pull out bricks and apply new insulation.

Before we do that, I thought I'd throw the question out there for you all, what is the best way to insulate these pipes so they don't freeze? Currently all lines into the house have foam wrappers and tape. I can't see the lines in the wall, but I have to assume there's nothing, or they wouldn't have frozen, right? I do know they are PEX pipe, so my plumber couldn't unfreeze them by warming them up from outsidee.

We had one side thawed out and running, and I ran the hot water last night and they still refroze.

Thanks in advance for any help!

Deb