I have been going back and forth with a TPR valve that dripped a tiny bit of water. I think I have ruled out most of the possible causes except temperature.

If the TPR released because of temperature I assume there would be significant water not just a few drips....thinking being it would take more than a tablespoon of water to lower the temperature!! Is that a fair assumption?

Also I have an energy cutout feature on the water heater... I think it cuts off the gas supply if the temp reaches 200. That's a few degrees less than the TPR. Would I be getting fault codes on the Honeywell gas valve before a T&P would release on a temperature issue? In other words, it would trip on fault before it overheated correct?


PS- I now have a new expansion tank and a new TPR there has also been no pressure spikes in the house for 72 hours of normal operation and I am running it a little cooler than before... all seems good--- knock on wood---- but I wanted to know how to proceed with troubleshooting if this would occur again.

I appreciate it.
ddbbp

When a T & P releases on temperature, it dumps full bore until enough cold water reenters the tank to cool the sensor and shut the T & P off.

thanks, I appreciate you confirming what I was thinking.

Further, I assume in an overheating situation, the ECO would turn off the heater before the TPR would activate anyway.



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you should run your water heater at normal temperatures (between 120 and 140 F.) and expect normal operation of everything on the plumbing system. My tank at home is at 125 F. Use a meat thermometer running under a faucet to check the temps., preferring a faucet with two handles as opposed to one so that you know that you are getting only hot water and also best if the faucet is close to the tank, like a laundry tub faucet.
Some TPR valves go bad over time without being exercised and under constant pressure and will dribble. It's good that you replaced it as I'm sure you don't test it every 6 months.
It's also important to use a gauge to test your water pressure before installing the thermal expansion tank and precharge the air bladder to match the house water pressure. This will prevent over extending the bladder after installation and causing premature failure as well as reducing the acceptance volume of the expansion tank and making it almost useless. This is, of course, if you have a closed plumbing system with a regulator and/or backflow protector on the water service.

The only valves that I have seen "go bad over time" have calcified shut and no longer operate at all; I have never seen an old valve start leaking without Temperature/pressure/someone screwing with it.

Well, it's good to know that my TPR valve will never go bad as long as my temperature stays below 210 deg.F and pressure below 150 psi. and I never touch it. You know come to think of it, I've never seen a valve drip on its own before just by sitting there unless there was a darn good reason for it. I don't even know why manufacturers recommend testing of the TPR valve, since as long as you don't touch it it will last forever...y'know testing it doesn't even simulate high pressure or temperature and so, by deduction, screwing with must be the logical reason most TPRs leak on a perfectly healthy hot water system. I'm glad you set me straight on this, KC. I was under the impression all of these years that pressure and heat on a mechanical appurtenance over a long period of time could cause some sort of wear on a seat or spring. I feel like a complete jackass for even making the comment and it was proper that you stepped up and corrected me on that specific segment of my statement. I'll be sure to put labels on all TPR valves that I install, from now on, that read "Just Don't Screw With It" so customers know that their forever valve will truly be forever. I wonder if the same can be said about RPZ backflow devices?...Hmmmm. Got me thinking now.

KC or anyone else... I just want to be absolutely sure so I can rule out a faulty thermostat...

1. have you ever seen a TPR dribble a tiny bit because of a temperature issue? Is it possible it opens a tiny bit prior to full boar 210?

2. and is it likely, if it opened a tiny bit on pressure, that once they open they don't close all the way? In other words, you might see continuous minor leaking from a one time event....

3. And finally, what I describe about the ECO feature on the water heater.... If it cuts out at 200 then I am assuming (of course!) that a T&P temperature issue is impossible on this heater? That also this heater would eliminate the stacking effect with that safety built in?



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The point of my little rant was to express the fact that anything can fail at any time and also not perform as designed simply because we live in a physical universe with limitless variables constantly influencing everything in our lives and we are in a constant state of trying to adapt to that universe to make our lives safer and easier by developing methods full of the same fallbilities that make us human and unique. With that being said, I'll answer your questions.
1. Yes
2. Yes
3. A temperature issue is not impossible because of the redundancy of safety features. See above.^^^

So your saying its possible to dribble a tiny bit prior to 210, then in turn, that tiny bit (lets say a teaspoon) that is being replaced is enough to bring the temperature down in a 50 gallon water tank? That seems unlikely.

and I am assuming the ECO would have to be faulty in this case as well as it turns off the heater at I believe 200 degrees.

Of course anything can happen and it usually does but I need concrete logic here while troubleshooting.



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I would agree other than the fact that you are assuming that the ECO will work every time. It is possible that the ECO won't work correctly because it was built with the cheapest components by the cheapest vendor with the loosest quality control. I would say that T+P discharge is most likely due to pressure when dealing with electric tanks, but high pressure is generally directly related to thermal expansion in a closed system.

No, I'm saying that the element could eventually fault and cause variances in the operation of the TPR valve. That's all. The best way to see if you have excessive hot water is to use a thermometer, as I said above, and check your water temperature. You can run some water, check it. let the tank fire and satisfy the thermostat, check the temp again and repeat as many times as you want to see if you get a spike in temperature.
You can also be experiencing thermal expansion or the TPR could just be boogered up inside, if it's dripping constantly, and needs to be replaced.
I have serviced tanks before that sat for years that show no temperature issues, no thermal expansion issues and the TPR was untouched and they still had a drippy TPR valve. Once replaced, tested the system again and all was normal.
A normally functioning TPR valve will spew water on temperature and dribble on pressure, but anything is possible. It's important to exercise the TPR as per manufacturer's recommendations, meaning open it and make sure it releases water and closes off properly.
If it drips again, check the temp from a faucet as explained above. If temp is okay, get your gauge (the one you used for checking your pressure before installing the expansion tank) and check pressure. If that's okay, check the bladder of your thermal expansion tank to see if it has air or enough air to match your house pressure; this is done with a tire gauge after you shut off the water to the house, open a faucet to relieve the house pressure and put the tire gauge on the air port of the expansion tank.

Given his previous post about water heater temperature overshoot [www.plbg.com] it is possible that the problem is in the gas valve and that the temperature isn't reading correctly. I still think the issue is due to pressure, but if pressure can be ruled out 100%, then the gas valve is the only possible source of the problem.

And on that note: An infra red thermometer will not give you an accurate reading of water flowing from your tap. Use a meat thermometer.

Nobody confirmed for sure though.... is my assumption correct?... a dribble from a TPR would be more likely a pressure situation. Becuase if this was a temperature issue.... it would have dumped more than a teaspoon of water. A teaspoon of water would not satisfy a temperature reduction in a 50 gallon tank. Additonally, the TPR opening on my heater because of temperature is unlikely since the heater has an Energy Cut Off at 200 degrees.



" An infra red thermometer will not give you an accurate reading of water flowing from your tap. Use a meat thermometer."

I'll bite, why is that? Certainly has to be more exact than a meat thermometer!



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"A normally functioning TPR valve will spew water on temperature and dribble on pressure,"

You also said a dribble WAS possible from temperature a few posts ago.

I think we have already talked in circles enough about the thread subject and it took too long to get to this point before we start discussing why infra red does not read accurately on flowing tap water. If your want to use your infra red, go ahead. I'm sure if I explained it with facts, somebody would just contradict me anyways or not thoroughly read my explanation and keep asking the same question again. Google it.

Ddbbp, you are over analyzing information to the point of confusing yourself. I feel sorry for the server at the restaurant you frequent. Your questions have been answered.

Scotttheplumber- You are partly right with one thing though, my question was answered until Caduceaus threw a wrench into the works with his contradiction. Now I am just confused.



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I never contradicted myself at any time. I just continued to be more thorough in my answers as you seemed to have a difficult time with the simplicity of first answers and started over thinking it. Your replies actually give the impression that you just skimmed over the replies and extrapolated on what you didn't read.