TPRV extention materials

Will someone please list all the acceptable materials for use for TPRV

Galvanized steel, hard-drawn copper, CPVC

Thanks Stephen,
My code check book says that you can use the same materials allowed for water distribution, but it doesn’t list pex (it lists the same materials that you listed). I have seen pex used frequently and write it up as wrong, but it is accepted for water supply. Do you write up pex when used for TPRV extension?

Pex is fine for the TPR discharge.

It depends on your AHJ, but Mr. Larson is correct - PEX is generally accepted for this use. . .

thanks guys

The problems with PEX are minor.

It needs to be secured more than the other materials since it is more flexible.

It is also affected by sunlight so if the water heater is in say a utility room with a window, the PEX should be covered. If the TPRV is routed to the exterior as it should, the termination point in sunlight should be protected or a different material.

For the supply lines, there must be 18" of metallic or approved piping between the water heater and any PEX. It makes sense that it would be for the TPRV also. Just a thought.

Hi Stephen,

Could you provide the source for this requirement, please?

Uniform Plumbing Code (2003). I know some don’t go by the UPC but some of the manufacturers quote this in their installation guidelines. There are parts made specifically for water heater and PEX connections…

Stephen is correct. . .

**604.11.2 Water Heater Connections.
**PEX tubing shall not be installed within the first eighteen (18 inches (457mm) of piping connected to a water heater.

The TPRV extension should terminate 2 -6 inches from the ground. It must be visible and not be routed to a crawlspace or exterior.

Sorry to disagree, you are only partially correct. It should not terminate in the crawl space. But the best application is to route to the exterior, to within 6" of the ground.

Actually you are both correct, depending on which code your area follows. The Uniform Code says the termination should be between 6" and 24" from grade or finished floor, and the International Code says not more than 6" from grade or ff.

Also, with manufactured homes, Federal guidelines allow a termination into the crawl space.

"2. Discharge through an air gap located in the same
room as the water heater.

  1. Discharge to a termination point that is readily
    observable by the building occupants."

Ahh, the UPC…thanks, gentlemen.

Given that the benefit of using PEX is supposed to be labor savings, it would seem to be contradictory to use PEX for this purpose if you have to install an 18" piece of something else and provide additional anchoring anyway.

Copper stubouts at fixtures and the required 18" at water heaters are very common around here when used with PEX.

That’s what they do here. Use the copper stubout, install the shut off valve, expansion tank, and copper flex line to the heater.

From yesterday’s inspection, copper pipe throughout EXcept this discharge line on a replaced tank. The label says “tighten by hand only”.

John Kogel