TL;DR
A dielectric union is a pipe fitting that joins copper to galvanized steel while a plastic sleeve and gasket inside keep the two metals from touching, blocking the galvanic current that would otherwise corrode the steel side at the joint. The classic location is a water heater's nipples, where codes or manufacturer instructions often require isolation between dissimilar metals.
What it means
A dielectric union is a pipe fitting that joins copper to galvanized steel while a plastic sleeve and gasket inside keep the two metals from touching, blocking the galvanic current that would otherwise corrode the steel side at the joint. The classic location is a water heater's nipples, where codes or manufacturer instructions often require isolation between dissimilar metals. Plumbers are divided on the fitting itself, since the unions can clog with mineral deposits over time; brass nipples or a short brass ball valve between the metals achieves the same isolation and often outlasts it.
Where it sits in the glossary
Dielectric union is part of the Trade jargon group inside the ProFix Directory glossary. Browse every term in this category from the glossary index.
Why Ohio homeowners should know it
This is a term Ohio homeowners encounter when reading contractor quotes, hiring paperwork, or inspection reports. Understanding it well enough to ask one good follow-up question is usually all the protection a homeowner needs.
ProFix Directory keeps definitions short on the index page and saves the longer context — Ohio-specific rules, where the term comes from, and which ProFix tools touch it — for these per-term pages so the term is easy to cite and easy to share.
ProFix tools that touch this term
See also
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