Is PEX Safe for Hot Water Recirculation Systems?

[Carl B.]

I’m designing a hot water recirculation loop for a second-floor bathroom that takes forever to get warm water.
I was thinking of using PEX-A for the loop, but someone told me continuous recirculation might degrade it.


Should I switch to copper for the return line? Or is high-temp PEX fine?

 

[Miller88]

PEX-A can handle it, but two caveats:

1. If your water heater is set above 140°F (not recommended), long-term PEX degradation is possible.
2. Watch for chlorinated water — high chlorine + heat = bad combo for plastic piping.
   If this is a forever home and budget allows, copper's the safe bet. Otherwise, oxygen-barrier PEX with proper insulation should be fine.