Can we get a deep dive on why construction plans keep calling for PEX on hot water recirc lines?

I've been plumbing for 12 years and in the last 6 months I've seen three new builds where the engineer spec'd PEX for the hot water recirculation loop. That's a known failure point because the constant flow eats the pipe from the inside out. Last job we had to repipe a whole 4,200 square foot house after 18 months because pinhole leaks showed up. Has anyone else run into this and found a good way to push back on the spec without getting fired?

3 comments

3 Comments

the_robin8d ago

Ask the engineer if they've ever actually ripped open a PEX recirc loop that's been running for two years straight. What I saw was the inner layer all scoured up, like someone took sandpaper to it, and the fittings were weeping before the pipe even gave out. Were these guys just copying specs from old projects or did they actually calculate the flow velocity? Cause I'd love to hear their reasoning.

anthony7639d ago

three new builds where the engineer spec'd PEX" - yeah that's a nightmare waiting to happen lol

fiona_hunt718d ago

Oh yeah, I had PEX in my last place and the recirc loop started pitting after like 18 months, it was a mess.