Thread: Tankless WH TPR

Checked the manufactures installation and there is no call for the TPR to terminate to the exterior. I dont see too many tankless and the ones I do typically terminate to the exterior. So does manufacture trump local standard?

Similar Threads:

• Tankless Water Heater in Stud Wall
• Exterior tankless water heater
• Tankless water heater comment
• Best way to "finish" tankless vent?
• Earthquake strap for tankless water heater

Originally Posted by Marc M

Checked the manufactures installation and there is no call for the TPR to terminate to the exterior. I dont see too many tankless and the ones I do typically terminate to the exterior. So does manufacture trump local standard?

No, Yes, and it depends!

The WH manufacturer does not make the TPR valve.
The TPR valve manufacturer defaults to the local AHJ!

LOL... Masterfully articulated.

Hi Marc, I have installed only 2 tankless water heaters by Poloma and Reehm. Here is what the instructions call for by the manu. A new pressure relief valve, complying with the Standard for Relief Valves and Automatic Gas Shut-OFF Devices for Hot Water Supply Systems, ANSI Z21.22/CSA 4.4, must be installed at the hot water outlet connection of the water heater at the time of the installation. Local codes shall govern the installation of relief valves.

Reading out of the 2003 IRC P2803.6.1 Requirements of discharge pipe. The outlet of a pressure relief valve, temperature relief valve or combination thereof, shall not be directly connected to the drainage system.

I hope this helps.

Yes it does...thanks for the reply.

Found this...
P2803.6.1 Requirements for discharge pipe.

The discharge
piping serving a pressure-relief valve, temperature
relief valve or combination valve shall:
1. Not be directly connected to the drainage system.
2. Discharge through an air gap located in the same
room as the water heater.
3. Not be smaller than the diameter of the outlet of the
valve served and shall discharge full size to the air
gap.
4. Serve a single relief device and shall not connect to
piping serving any other relief device or equipment.
5. Discharge to the floor, to the pan serving the water
heater or storage tank, to a waste receptor or to the
outdoors.
6. Discharge in a manner that does not cause personal
injury or structural damage.
7. Discharge to a termination point that is readily
observable by the building occupants.
8. Not be trapped.
9. Be installed to flow by gravity.
10. Not terminate more than 6 inches (152 mm) above
the floor or waste receptor.
11. Not have a threaded connection at the end of the piping.
12. Not have valves or tee fittings.
13. Be constructed of those materials listed in Section
P2904.5 or materials tested, rated and approved for

such use in accordance with ASME A112.4.1.