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Q. I recently went to a home center to get PVC pipe and fittings for roughing in a new bathroom in my basement. I found two styles of fittings, one with smooth surfaces and the other with flanges wherever the pipes join into the fitting. No one there seemed to know which one I should use. Are they for different purposes? Which should I buy?
A. You should buy the ones with the hubs (what you call flanges). They’re designed for drain waste vents (DWV). The other type is for pipes that carry water under pressure. Called pressure fittings, they’re used in homes for some types of groundwater heating systems and swimming pool plumbing. The fittings are thicker and stronger and allow the pipe to penetrate farther into the fitting to reduce the chance of failure. Using pressure fittings for drain waste vents won’t meet code in most areas.
P.S. People who make cool stuff out of PVC pipe (lawn furniture, for example) like to use pressure fittings for their clean, neat look.
