Water Heaters 101> Plumbing Connectors

What you'll find on this page: What connects your water heater to your plumbing? You probably never gave it much thought. There are several options and some are better than others.

The options are:

• Soldered solid copper screwed onto a pipe nipple
• PEX or PVC screwed onto a pipe nipple
• Flexible copper
• Flexible stainless steel
• Dielectric unions

Four of the five types are shown in these photos: top right, copper flex, bottom right, dielectric union on the left and stainless flex on the right; and at left, copper screwed onto a steel nipple.

Solid copper can work, although if you ever want to open the tank for anything, it will all have to be taken apart. We've seen copper screwed onto PEX-lined FE nipples with no signs of leakage, but using brass nipples is probably a safer bet because if any place where the steel and copper connect gets wet, the steel will rapidly rust. PVC and PEX will also work with the same caveat. If you ever expect to disconnect the plumbing, you'll need one of the other three. Of those, we like dielectric unions the least. They often leak. They don't do well at keeping dissimilar metals apart, so the steel often rusts. They're hard to disconnect, and once that's done, it's often very hard to get them far enough apart to, say, pull off the cover of a commercial heater to get at the anodes.

For residential heaters, we prefer copper flex lines threaded on both ends and screwed onto a male adapter on the plumbing end. They are cheaper, work well and last a long time. The older they get, the more brittle, so moving them much may cause a leak. We like stainless flexes, but especially the corrugated kind. If you consider braided ones, make sure they don't have a rubber lining. That has been known to disintegrate in some kinds of water.

In all cases, it's very important to go back in six months and tighten everything, as the rubber gaskets inside most of these shrink with heat and cause leaks. We've seen scores of commercial heaters that were ruined this way.

 

 

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