g/plumbing • Posted by u/pex_pioneer • 1 days ago

PEX-A vs PEX-B for radiant floor heating — is PEX-A worth the extra cost?

Pricing out a radiant floor heating system for a 3,000 sq ft addition — about 1,200 feet of tubing in a concrete slab. The spec says PEX-A but my supplier is pushing PEX-B at a significant cost savings.

PEX-A (Uponor AquaPEX) is about 40% more expensive than PEX-B (Viega or Watts). For a slab application where it's encased in concrete, is the PEX-A flexibility advantage actually relevant? The slab isn't going to be serviced.

Arguments I've heard for PEX-A: kink recovery, longer coil lengths, better burst pressure at high temps. For a radiant system running at 110°F max, do those matter?

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u/boiler_bill • 1 days ago

Agree with the above. Both PEX-A and PEX-B exceed the performance requirements for a low-temperature radiant application (under 140°F). Where PEX-A genuinely wins is high-temperature applications (like domestic hot water over 180°F) and mechanical rooms where the tubing is visible and might get disturbed. In a slab? Save the money.

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u/drain_dave • 1 days ago

One thing to verify: your manufacturer's warranty terms. Some radiant system manufacturers specify PEX-A in their warranty requirements. If the spec says PEX-A and you substitute PEX-B, document the substitution and get approval — you don't want a warranty dispute 10 years from now over material substitution.

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u/pipefitter_pat • 1 days ago

For a slab application, the kink recovery advantage of PEX-A matters primarily during installation, not long-term. If your installers are careful about bend radius during layout, PEX-B is fine in the slab. PEX-A matters more in retrofit situations where you're threading tubing through tight spaces. For new slab, I'd take the cost savings.