Thread: TPR terminates to garage floor interior

Need some clarification on this common issue and weather it should be a recommended upgrade, further review or repair. Also how would you answer this question.


Question from client(Hunch that it is actually coming from sellers agent) based on similar tactics from this particular agent in the past.

Q: On the TP relief value you recommend this be re-routed to the outside per industry standards. We can assume the recommendation is the industry standard. Can you tell me if that was an industry standard when this house was built or are you recommending this house be brought up to current code?

The home was built in1981. There were no obvious indications that the garage was converted from a carport which is very common here in Southern AZ. appears to be the original configuration with newer water hater installed in 2012. It could easily be routed to the exterior. It is readily observable, 6 inches above floor. Questionable part is with this termination location does it discharge as to not cause personal injury or structural damage??

Finding dates (1981) regarding these requirements were unsuccessful.

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Originally Posted by Ryan Castillo

Q: On the TP relief value you recommend this be re-routed to the outside per industry standards. We can assume the recommendation is the industry standard. Can you tell me if that was an industry standard when this house was built or are you recommending this house be brought up to current code?

The home was built in1981. There were no obvious indications that the garage was converted from a carport which is very common here in Southern AZ. appears to be the original configuration with newer water hater installed in 2012. It could easily be routed to the exterior. It is readily observable, 6 inches above floor. Questionable part is with this termination location does it discharge as to not cause personal injury or structural damage??

Finding dates (1981) regarding these requirements were unsuccessful.

In 1981, the T&P discharge piping was required to extend to, and terminate, outside.

In 2012, the T&P discharge piping was (and still is) required to terminate in the same room or space where the water heater is located. This requirement goes back to maybe 2003 or 2006, I'd have to look it up to verify when it changed.

The T&P relief valve discharge piping was required to meet the code in effect at the time the new water and new T&P were installed - i.e., the discharge piping had to be rerouted to terminate in the same room or space as the water heater was located.

These are the requirements: (bold and underlining are mine)
- 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 P2905.5 or materials tested, rated and approved for such use in accordance with ASME A112.4.1.

IF ... if one can convince the AHJ that discharging to a concrete floor causes structural damage (not likely) or causes personal injury (a possibility, but a hard sell to some AHJ), while still meeting items 2 and 7.

There are ways to do it, such as discharge to the drain pan (allowed by the code, but then it creates issues from the manufacturer and the code as water heaters are not listed for being installed partially submerged in water, and the water heater will be when the T&P is tested or leaks or ... as not all the water drains out the drain pan drain - and is only permitted if the drain pan drain actually meets the requirements and is not PVC, etc.).

Another way to do it is to discharge to an air gap - the problem now is finding a suitable air gap which will accept the discharge without spewing water out all around it and which will take the discharge and not overflow (overflow will create the same issue as discharging to the floor).

Yes, most discharge to the floor in the garage. I am not aware of any slip and fall caused by a T&P discharging to the floor - is anyone aware of such an incident?

Jerry,
Thank you for your prompt response.

Did I understand correctly that in 1981 the requirement was "must be routed to the outside" and then changed to terminating in the same room/not outside in 2003 -2006 ?

So if the configuration was original it was not built to code in 1981 but essentially is to code now or as of the installation in 2012?

Is it unreasonable to suggest it could damage the structure of the interior wall it is coming out of in the event of a discharge?

Thanks again!

Originally Posted by Ryan Castillo

Did I understand correctly that in 1981 the requirement was "must be routed to the outside" and then changed to terminating in the same room/not outside in 2003 -2006?

Before the ICC codes were the old model codes, such as the Standard Building Code, Uniform Building Code, National Building Code, BOCA Code (for 1&2 family dwellings wherever it was adopted), and other national model codes.

My recollection is that they required it to be discharged to the outside, however, there may have been an option in some of those code to discharge it to the inside through an indirect waste receptor (floor drain or such) as some areas had to worry about the discharge pipe freezing or that "outside" meant "uphill" and trapping the discharge line was not permitted (such as would be the case with a water heater in a basement).

From the 2000 IRC: (bold and underlining are mine)
- 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. The discharge from the relief valve shall be piped full size separately to the outside of the building or to an indirect waste receptor located inside the building. In areas subject to freezing, the relief valve shall discharge through an air gap into an indirect waste receptor located within a heated space, or by other approved means. The discharge shall be installed in a manner that does not cause personal injury or property damage and that is readily observable by the building occupants. The discharge from a relief valve shall not be trapped. The diameter of the discharge piping shall not be less than the diameter of the relief valve outlet. The discharge pipe shall be installed so as to drain by gravity flow and shall terminate atmospherically not more than 6 inches (152 mm) above the floor. The end of the discharge pipe shall not be threaded.

The 2003 IRC was similar to the above.

The 2006 IRC was basically the same as I posted previously, which was from the 2012 IRC, and requires the discharge to be:
- 2. Discharge through an air gap located in the same room as the water heater.

So if the configuration was original it was not built to code in 1981 but essentially is to code now or as of the installation in 2012?

Not quite sure what you are asking ... an original installation (which met code at the time) is permitted to remain ... until something is changed, such as the water heater being replaced, then the water heater installation (including the T&P relief valve and the discharge pipe) must meet the code at the time it was replaced (2012 in this case).

If that garage was a carport back in 1981 ... then that water heater should not have been installed in the carport anyway as that water heater is not listed for use outdoors - there are special water heaters which are listed for use outdoors, but they are unmistakable in that they do not look like regular water heaters, they have their own built in 'shed enclosure' around them, with the water heater safely protected from the weather inside it (okay, that may not be a good description of a water heater which is suitable for use outdoors).

[quote]Is it unreasonable to suggest it could damage the structure of the interior wall it is coming out of in the event of a discharge?

If it is discharging to the floor in the garage, how could it damage the structure's interior wall? I am missing something in your description.

[QUOTE=Jerry Peck;257716]In 1981, the T&P discharge piping was required to extend to, and terminate, outside.

In 2012, the T&P discharge piping was (and still is) required to terminate in the same room or space where the water heater is located. This requirement goes back to maybe 2003 or 2006, I'd have to look it up to verify when it changed.

The T&P relief valve discharge piping was required to meet the code in effect at the time the new water and new T&P were installed - i.e., the discharge piping had to be rerouted to terminate in the same room or space as the water heater was located.

The home was constructed in 1981, if the garage was original (Which there are no obvious indications that it is not) then the termination is not to outside per old code nor is it in the same room as the water heater per current code. The water heater is in a room off of the garage separated by the wall in the picture.

Originally Posted by Ryan Castillo

The water heater is in a room off of the garage separated by the wall in the picture.

Okay, the water heater was in the garage and T&P was discharging to the garage floor, but the water heater is actually in a closet ... so where does the T&P actually discharge to?

The better your description of what is there, the more accurate the answers you will get, and the fewer times we will need to keep adding to the description to know what is there and where.

The T&P goes through the wall behind the water heater and discharges into the garage behind it - is that water heater room "in the garage" or is it a "separate room"?

If there is just a wall separating the water heater from the rest of the garage, then the water heater could be considered to be in the same room as the discharge.

If the water heater area has a door on it which makes it a separate room, then it would not be correct.

The water heater is in a room off the garage approximately 6'X8' with double doors from garage to water heater room and another door from water heater room to exterior. The TPR pipe runs through wall separating garage and water heater room to terminate at garage floor.

My apologies for not being more descriptive.

Thanks again for your help!

My recollection regarding the BOCA code is that the TPV should not terminate outside. We are in the land of basements and cold weather. Terminating outside typically requires the discharge to go uphill, which is not permitted. TPVs here typically terminate at the floor (with no drain). In newer houses on slabs (which are mostly condos) they often terminate to a drain, but not outside.

Regional practices vary quite a bit.

Washington State is under the UPC so has little different such as height of discharge "6 to 24 ", and there is WAC Amendment that allows floor discharge for replacement water heaters.


608.5 Drains. Relief valves located inside a building shall be provided with a drain, not smaller than the relief valve outlet, of galvanized steel, hard drawn copper piping and fittings, CPVC, or listed relief valve drain tube with fittings which will not reduce the internal bore of the pipe or tubing (straight lengths as opposed to coils) and shall extend from the valve to the outside of the building with the end of the pipe not more than two (2) feet (610 mm) nor less than six (6) inches (152 mm) above the ground or the flood level of the area receiving the discharge and pointing downward. Such drains may terminate at other approved locations. No part of such drain pipe shall be trapped or subject to freezing. The terminal end of the drain pipe shall not be threaded.


Exception: Replacement water heating equipment shall only be required to provide a drain pointing downward from the relief valve to extend between two feet (610 mm) and six inches (152 mm) from the floor. No additional floor drain need be provided.



- - - Updated - - -

Washington State is under the UPC so has little different such as height of discharge "6 to 24 ", and there is WAC Amendment that allows floor discharge for replacement water heaters.


608.5 Drains. Relief valves located inside a building shall be provided with a drain, not smaller than the relief valve outlet, of galvanized steel, hard drawn copper piping and fittings, CPVC, or listed relief valve drain tube with fittings which will not reduce the internal bore of the pipe or tubing (straight lengths as opposed to coils) and shall extend from the valve to the outside of the building with the end of the pipe not more than two (2) feet (610 mm) nor less than six (6) inches (152 mm) above the ground or the flood level of the area receiving the discharge and pointing downward. Such drains may terminate at other approved locations. No part of such drain pipe shall be trapped or subject to freezing. The terminal end of the drain pipe shall not be threaded.


Exception: Replacement water heating equipment shall only be required to provide a drain pointing downward from the relief valve to extend between two feet (610 mm) and six inches (152 mm) from the floor. No additional floor drain need be provided.