TPRV, to test or not to test...

[jodil]

Great info guys. So if the valve gets stuck open just how much water can potentially come out? Im going to practice on mine and fams this weekend, before I ruin someones basement floor...

[Richard Moore]

"So if the valve gets stuck open just how much water can potentially come out?"

As hose bibs are usually served by 1/2" lines and a 3/4" discharge has roughly twice that capacity...then (assuming everything upstream of the WH is also => 3/4") it would be like fully opening 2 hose bibs. The actual amount would depend on supply pressure but, in other words, a whole lot before you had the presence of mind to shut the water supply off to the water heater. I told you there would be "some" disagreement on testing these. [] I recommend that YOU do NOT test those that discharge inside a home.

[Richard Stanley]

"I recommend that YOU do NOT test those that discharge inside a home."

And, effective with the 2006 IRC, the tp drain pipes must terminate in the same room where the water heater is located.

[Brandon Chew]

Originally posted by Jim Katen

Originally posted by allspec33351

I like this

http://www.onthehouse.com/wp/19940207

mlc

Ok, I'm beginning to come around.

From the article:

According to a survey done by Domestic Engineering Magazine, approximately one of every three T & PR vales is frozen shut and non-operational.

Does anyone have access to this survey or know anything about it?

- Jim Katen, Oregon

Mitchell linked to a reprint of the article in post #13.

T&P Valve article in May 1986 issue of Domestic Engineering magazine

The On The House website mis-interprets what the article says.

Lopp works(ed?) at Modern Electric Co., a water utility in Spokane, WA. They sent info to their customers about how to do a self-inspection of their TPR and asked them to report the results. Results were:

18 percent, no T & P valve installed

two percent, T & P valve incorrectly installed

four percent, pressure only relief valve

one percent, T & P valve would not discharge

less than one percent, T & P valve plugged.

"However, Lopp says that 15 percent of the T & P valves inspected by his company would not discharge, leading them to believe that the figure for unprotected hot water heaters in their area is closer to 30 percent."

My analysis: The 30 percent figure for unprotected water heaters comes from adding the 18 percent with no TPR reported by customers to the 15 percent reported by his company that would not discharge, and then rounding off.

Regarding "On The House", "one in three" is another way of saying 33 percent. They are referring to the "closer to 30 percent" figure in the DE article that that I quoted above. They incorrectly state that as the number for TPRs being "frozen shut".

The correct number that should be attributed to Lopp for stuck TPR valves is 15 percent, not one in three, and this is based on the utility's experience from doing their own inspections and not from the customer survey.

[Les]

there has to be a little common sense here.

inspectors are not lifesavers.

most inspectors don't have a clue about the actual valve and how it works.

opening the valve can accomplish nothing.

I have been in the room when the valve has opened.

look at the history of this device.

searching the web 'till your green is no substitue for knowledge.

Jodi, open the one on your own water heater so you will know. Go to Home Depot or the hardware store and look at one.

I don't know what is wrong with me, but I've never seen myself as saving anyone. I just know more than my client.

As for the list of questions - much the same as Jim K.

This type discussion is really good for a round table format.

[mthomas1]

5 gal heater trashes high-school lunchroom:

http://www.safteng.net/Accident%20Photo ... losion.htm

[Brandon Chew]

Originally posted by Richard Stanley

And, effective with the 2006 IRC, the tp drain pipes must terminate in the same room where the water heater is located.

That is not correct.

2006 IRC P2803.6.1 says the discharge may be to the floor, to an indirect waste receptor, or to the outdoors. There must be an air gap in the same room as the water heater.

[allspec33351]

Based on opening thousands tprv I would say the percentage of "stuck

" valves is about 1%-2%.

The number that stay open are between 1/2%-1%. Please note that a gentle tap on the top of the tprv usually stops the leak at least until I leave.

I would say the decision to not test by inspectors is based on the fear of repercussions of a stuck valve and not based on whether testing of the valve is a legitimate test.

mlc

[allspec33351]

Originally posted by Brandon Chew

Originally posted by Richard Stanley

And, effective with the 2006 IRC, the tp drain pipes must terminate in the same room where the water heater is located.

That is not correct.

2006 IRC P2803.6.1 says the discharge may be to the floor, to an indirect waste receptor, or to the outdoors. There must be an air gap in the same room as the water heater.

I have only tested one with an air gap and it doesn't work. Nor can I see how one can work.

mlc

[hausdok]

Well Mitchell, not to be contrary, but my experience was 100%.

The one and only time I tested one, it stuck open and refused to close. It was my first year in the business. I'd been told by veterans in the business during training that testing TPR valves and main shutoff valves on plumbing wasn't a good idea. I figured, "Ah, what could happen; it says right on the valve to test it," so I didn't believe the propaganda. The logic of not screwing around with main shutoff valves that look like they were forged in the 17th century made sense to me but not the argument against TPRs. Still, for months after getting into the business I didn't test them 'cuz I wasn't willing to test my theory.

Then one day I got a customer who was like, "Well, how do you know if the thing is going to work when it should if you don't test it?" I could sense that this client was a little bit anal retentive like myself, so I decided to humor him. I flipped the valve, released the handle, and the water just kept on coming, whereupon the customer stood there smiling like a cheshire cat, because he thought he'd somehow found a defect that I would have missed, when in reality we wouldn't have known one way or the other by not testing it - it might have worked when needed but then wouldn't have closed; who's to say?

Anyway, I tapped on it, I pushed, I pulled - nothing; it just kept pouring water all over that basement floor. Fortunately, it was one of the older houses with basement and a floor drain very close to the tank, so I shut off the water to the tank and it didn't do any damage. I finished up the inspection and then talked the agent into hanging around so I could fix the valve. I jumped in my car, scooted over to a nearby Ace Hardware, picked up a new TPR valve, a soldering torch kit with some flux, solder and pipe dope, shot back to the house, did a lickety-split valve change, and then drove all the way to the next job with the afterburners on, breaking every traffic law on the books. Still, I was so late for the next job that I punished myself for my stupidity by taking $50 off the price of the inspection. At the end of the day, I ended up with a whole lot less in the blue column than I'd intended and was stuck with an extra soldering torch, flux, and a can of pipe dope.

Now, sure, I could have written up the valve and allowed a plumber to deal with it, but the admonitions of those veteran inspectors during training not to dink with those valves if I didn't want them to dink back kind of rung in my ears. I tend to punish myself for my boners. Now, I don't care how anal retentive the customers are; I'm not testing them. If the client insists on knowing whether they work, I tell them to have the homeowner demonstrate the valve for them; preferably when I'm not in the home.

ONE TEAM - ONE FIGHT!!!

Mike

[Richard Stanley]

P2803.6.1 Requirements for discharge pipe. The discharge

piping serving a pressure-relief valve, temperaturerelief

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 an indirect waste receptor

or to the outdoors. Where discharging to the outdoors

in areas subject to freezing, discharge piping

shall be first piped to an indirect waste receptor

through an air gap located in a conditioned area.

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.

[Brandon Chew]

Thanks Richard. My 2006 IRC is the paper version and that was too much for me to type with one hand.

[ozofprev]

Originally posted by Brandon Chew

Thanks Richard. My 2006 IRC is the paper version and that was too much for me to type with one hand.

You still have all ten toes, right? You could tighten those abs while typing!

[Jason B]

Here's a link that fun for the whole family! I think Mythbusters did a similar test with similar results a few years ago as well.

http://www.waterheaterblast.com/index.html

[BADAIR]

Not trying to change anyone's mind or opinion but I'll be testing them until they pry my corpse off the toggle

this isn't a difficult test/examination

1 confirm properly plumbed cut off valve presence, TPRV, drain line and termination

2 spin toggle any resistance call qualified plumber to replace $10-$20 valve because it failed under testing

if 2 was completed successfully without resistance

3 lift toggle allow to re-seat if no discharge occurs or drainage persists call qualified plumber to clear drain line and/or replace $10-$20 valve because it failed under testing

Manufacturers recommend homeowners test yearly and qualified inspections occur every 3 years

This is what can happen from a malfunction or improper installation, evidence is still being collected, please click link and read the story for further information

http://www.azfamily.com/news/homepageto ... 75254.html

Photos are from my friendly AZ inspector Dale Duffy view and use at your own discretion

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[Bain]

Pretty amazing. Check out the video of the water heater a couple of blocks away.

[mthomas1]

On that one, the garage door ended up on the roof across the street:

http://gmy.news.yahoo.com/v/9293239

[Tim H]

Finally: Flipping the lever is meaningless. There's no way for the "flip test" to predict the behavior or the water heater or the TPR valve minutes or years into the future.

That is why I dont "test" them. You are not duplicating a failure mode when you use the lever. You are just testing the lever and the connection of the lever to the valve.

[msteger]

I personally don't operate the T&P valve for liability reasons.

[Bain]

Has anyone stopped to consider why the water heater exploded? I mean, imagine the temperatures and/or pressures that would have to be reached to cause the havoc in badair's photos.

Every once in a while, I'll start running water in a vacant house and the entire place will fill with this noxious, nearly-intolerable sulphuric acid odor due to some sort of chemical reaction that's occurred within the stagnant water. It gives me a wicked headache and makes me feel as if I'm going to hurl. I even had to open the doors and windows once to air a place out just so I could stay inside.

The reporter said a plumber laid blame on a faulty TP valve, but I'm thinking something else had to have happened to create such a gigantic explosion. I bet it was some sort of bizarre gas formation problem.

[hausdok]

Hi,

No, 50 gallons of super-heated water suddenly exposed to the air and expanding to steam at a rate of at least 100 to 1 in a split second is enough to easily do what happened there. It's exactly what happens when boilers of all sorts explode because it's exactly the same thing.

The noxious odor that gave you a headache was hydrogen sulfide gas that was caused by bacteria-laden water in a turned-off water heater reacting with the anode rod. It too is explosive but it doesn't occur in an occupied home; it occurs after a house is left vacant with the water heater off. Camping cabins and dishwashers have been known to explode due to ignited hydrogen sulfide gas when folks open up vacant homes and accidentally ignite it.

ONE TEAM - ONE FIGHT!!!

Mike

[hausdok]

When I saw that video above my first thought was; "I wonder how that TPR discharge pipe was configured?" I see so many of them that go uphill that I wondered whether that was the case and water had accumulated around the valve and caused it to corrode and stick. It would be interesting to see whether the guy had a home inspection when he bought and if the report called an improperly configured discharge pipe that he never bothered to get corrected when he moved in. IF that were the case, I wonder whether his insurance would pay or say, "Sorry Charlie, you forgot to exercise due diligence." Ooh, what if it was improperly configured and an inspector didn't call it out and that's what caused this? [:-bigeyes

ONE TEAM - ONE FIGHT!!!

Mike

[StevenT]

I do not test TPRs, or water mains, nor do I reset breakers that I have not intentionally blown.

But if you want to do so and are concerned about it not sealing, keep a bucket nearby or have a hose that can slip over the drain tube and reach a bucket or a sink. It will give you enough time to close the valve on the heater or boiler. If you shut the water on the boiler, shut off the power too. Don't burn yourself.

If a TPR valve is leaking, prior to tweaking the lever, the problem is not necessarily the valve. If could be the expansion tank or the water pressure regulator.

[Bain]

"50 gallons of super-heated water suddenly exposed to the air and expanding to steam at a rate of at least 100 to 1 in a split second."

I don't understand. How does that occur? And why don't water heaters explode more often?

I realize that's the purpose of the TP valve, but very seldom have I heard of one actually tripping due to a problem.

[charlieb]

When the hot water is no longer under pressure, open atmosphere, it expands exponentially and turns to steam. In an instant.

Why?

The controls must fail and the valve fail. The tank then fails and exposes the water to the lower atmospheric pressure.