Exploding Water Heaters -- Traps Going Up - IPC IAMPO

[TheOverThinker]

In our area inspectors are now tagging TPR valves that don't have a constant gravity drain slope, even in otherwise simple water heater replacements in basements. This is supported by IAMPO 608.5:

608.5 Discharge Piping. The discharge piping serving a temperature relief valve, pressure relief valve, or combination of both shall have no valves, obstructions, or means of isolation and be provided with the following:

(1) Equal to the size of the valve outlet and shall discharge full size to the flood level of the area receiving the discharge and pointing down.
(2) Materials shall be rated at not less than the operating temperature of the system and approved for such use or shall comply with ASME A112.4.1.
(3)Discharge pipe shall discharge independently by gravity through an air gap into the drainage system or outside of the building with the end of the pipe not exceeding 2 feet (610 mm) and not less than 6 inches (152 mm) above the ground and pointing downwards.
(4)Discharge in such a manner that does not cause personal injury or structural damage.
(5)No part of such discharge pipe shall be trapped or subject to freezing.
(6)The terminal end of the pipe shall not be threaded.
(7)Discharge from a relief valve into a water heater pan shall be prohibited.​

What's the safety reason behind prohibiting the line from going up and over to the outside? Under water heater pressure, it would easily blow out any standing water in a line that went up. For basement retrofits finding a way to get the TPR out can be a big constraint, leading to non-optimal water heater placement, and/or strange kludges like the Watts 210 for gas or stranger solutions for electric.

To see water heaters blowing up, see Mythbusters. They did it twice.
https://go.discovery.com/tv-shows/mythbusters/videos/exploding-water-heater
The pressure is immense.


Are there other places in the US or Internationally that allow a TPR exit pipe to be routed above the water heater, beyond Georgia?

*SECTION 504
**SAFETY DEVICES
*Delete Section 504.6.1 and substitute the following:
**504.6.1 IPC Discharge.

**The relief valve shall discharge full size to a safe place of disposal such as a concrete floor, outside the building, an indirect waste receptor, or other approved location. The discharge shall terminate in a manner that does not cause injury to occupants in the immediate area or structural damage to the building. The discharge pipe shall not be trapped. When the relief valve discharge piping goes upward a thermal expansion control device shall be installed on the cold water distribution or service pipe in accordance with Section 607.3.2 (GA.

Georgia GA Standard Plumbing Code (International Plumbing Code) Amendments 2002

Amendments). Provisions shall be made at the low point to drain the trapped portion of the discharge pipe.
https://www.dca.ga.gov/sites/default/files/2005_ipcamendments.pdf​

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For Georgia is a spring loaded drain valve at the low point acceptable, so nobody leaves it open?

 

[TheOverThinker]

Do any other states allow TPR piping to go up?

 

[Sponsor]

 

[Tuttles Revenge]

in washington state, they must be gravity drained.. no traps of any kind..

In a basement we would have to install a pressure only relief valve at a lower pressure than the T&P that can gravity drain.

Most of the time if some thing was compliant when installed then its grandfathered in, unless it creates a dangerous condition then an inspector could force that to be upgraded.. cross connections, t&p not installed or installed improperly etc.

 

[hj]

The governing bodies ALL PROHIBIT a "trapped" T&P discharge line. Even if it cannot freeze, the constant presence of water will corrode the interior of the valve.

 

[Terry]

The city of Bellevue used to require a 125 PSI relief on the cold water for the home.
A standard T&P is set for 150 PSI

And I would never, ever consider trapping or capping a T&P on a water heater. In the Seattle area someone capped a dripping T&P and the water heater blew through the roof of the home and landed a block away in the street Imagine getting hit by a water heater while driving to work

 

[wwhitney]

The governing bodies ALL PROHIBIT a "trapped" T&P discharge line. Even if it cannot freeze, the constant presence of water will corrode the interior of the valve.

Nice answer to the OP's question--the valve is designed to have air on one side, not to be constantly submerged, as it would be if the TPR outlet is higher than the TPR valve and any water is ever let out.

In regards to UPC 608.5, seems like the language in the OP would allow, for a basement with a sump pit, discharging the TPR into the sump through an air gap. If there's no sump pit, maybe a hot water lift pump could be had, and the TPR could discharge into a shallow basin connected to the hot water lift pump, plumped outside.

Cheers, Wayne

 

[Sylvan]

As a low pressure boiler inspector while in the boiler room I did check the water heater because if something happened after I did the my inspection and was lax in inspecting and the heater caused injury I would be liable damages


More then 90% of the discharge piping from water heaters is piped incorrectly and about 40% of boilers

 

[Sylvan]

Nice answer to the OP's question--the valve is designed to have air on one side, not to be constantly submerged, as it would be if the TPR outlet is higher than the TPR valve and any water is ever let out.

In regards to UPC 608.5, seems like the language in the OP would allow, for a basement with a sump pit, discharging the TPR into the sump through an air gap. If there's no sump pit, maybe a hot water lift pump could be had, and the TPR could discharge into a shallow basin connected to the hot water lift pump, plumped outside.

Cheers, Wayne

Pumping hot water /steam outside has better be careful as children /pets get scalded and if there is a discharge people inside the structure will not be aware of a problem

 

[Sylvan]

Here 1939

 

[TheOverThinker]

If there's no sump pit, maybe a hot water lift pump could be had, and the TPR could discharge into a shallow basin connected to the hot water lift pump, plumped outside.
Cheers, Wayne

I think the issue is that real TPR discharge is a lot of very hot water under pressure, which would overwhelm a lift pump.
I will post photos of the San Jose California solution soon.

 

[TheOverThinker]

2008

 

[Tuttles Revenge]

Saniflow makes small lift pumps that can easily handle the discharge from a water heater t&p

 

[TheOverThinker]

Saniflow makes small lift pumps that can easily handle the discharge from a water heater t&p

I asked my AJH about this, and they said "no way they'd approve it, regardless, even if the lift pump had a battery backup".

 

[Terry]

Sylvan,
Thanks for finding that video from 1939. That's the best video I've seen on exploding water heaters.

 

[Tuttles Revenge]

I recall in a code class by Dale Dobson that he showed a slide of a water heater that had exploded outwards rather than blowing out the bottom and it had cracked the concrete foundation of the church it was in. It probably wasn't reinforced concrete, but the force was massive.

 

[TheOverThinker]

Inspected and approved by AJH under IAMPO. In operation.
The up leg goes up about 3 feet, then gently slopes to the outside.
The pigtail goes down to the tray.
This is now a standard prescriptive design, anyone can use in my region.

 

[Tuttles Revenge]

Well you're now approved to make Moonshine! They approved a Still?

 

[Sylvan]

Sylvan,
Thanks for finding that video from 1939. That's the best video I've seen on exploding water heaters.

This is the video I saw when I took the low pressure boiler and under fired pressure course. amazing how this was made in 1939 and yet we still have boilers/ pressure vessels exploding

The Telephone Company Explosion of 1962
On October 3, 1962, at 12:07 pm, an overheated boiler exploded inside the New York Telephone Company building on Broadway and West 213th Street in the Inwood section of Manhattan. In the aftermath 21 persons were counted dead and 95 others were injured.

 

[Sylvan]

One of the sites I visited with a team of inspectors was in OK was just before this happened and we were doing a routine inspection to find as many code deficiencies as possibly OU wee noted several HUNDRED ASME code violations and yet OU claimed sovern immunity

19 blast that occurred when a hot-water tank exploded and ripped through the cafeteria of Star Elementary School in Spencer, Okla., killing a teacher and six students and injuring 34 others. The tragedy posed both immediate and long-term challenges for Oklahoma City school officials. Mar 17, 1982

 

[Sylvan]

Inspected and approved by AJH under IAMPO. In operation.
The up leg goes up about 3 feet, then gently slopes to the outside.
The pigtail goes down to the tray.
This is now a standard prescriptive design, anyone can use in my region.

View attachment 67413

I knew the "Left coast" had the best polititions money can buy but I never thought any normal code official would approve such a disaster waiting to happen

Even forgetting about the worst discharge piping I have ever seen did anyone ever bother to read about T&P installations and locations?

Placing a 3/4" Brass coupling then installing the T&P shows how demented the installer is

The T&P "SHALL BE" installed at the upper most 6" of the tank and have the probe inside the tank NOT piped asway with a coupling

Also I have seen a moron CUT the Probe and place it on the bull of the tee so they could use a Hose Bib on the run for a washing machine


This type of incompetency is how expert witness make a fortune especially when death occurs

Takes a certain mindset to even dream of this set up