Water heater pressure relief value drip

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About four months ago, we replaced our electric water heater. Last weekend the pressure relief valve started dripping small amounts of water intermittently. Some research/analysis resulted in a diagnosis of high pressure due to a one-way valve between us and the street; sure enough, it drips worse when we don't use water for long periods. And it only started recently because we have an Aprilaire humidifier (the kind that has a trickle of fresh water running through it whenever it's running), and of course just turned that off for the spring.
So. The question is: do I *need* an expansion tank? I was given two options: 1) Expansion tank. 2) Just run a tube from the valve to the floor drain nearby
My concern is whether option (2) -- easy, cheap, etc. -- is a good idea long-term. Will constant slight "blowing" of the valve cause it to fail catastrophically?
I found this on one site: "T&P valves are strictly an emergency measure and should be replaced every 2 years. At 180 psi , the temperature that the T&P valve opens, damage can occur to your system and you may have voided the warranty on your water heater." and: "Plumbing codes require that thermal expansion control be addressed in plumbing systems. A temperature and pressure relief valve is not considered a thermal expansion device. This is because when water is allowed to continuously drip from the T&P relief valve, minerals from the water can build up on the valve, eventually blocking it. This blockage can render the T&P valve useless and potentially lead to hot water heater explosions."
Obviously these concern me! I just don't want to $pend more dollar$ if I don't have to, though it sure sounds like I do have to.
Thanks in advance for any thoughts,
...phsiii
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Remove dots from userid to reply wrote:

Put the exp tank on; they are inexpensive and required.
If you just let it drip, the whole system is over-pressured, which can be damaging. Plus, the relief valve will soon wear out.
Jim
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Who told you to run the 'tube' from the valve to the floor?
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Actually, where I live, it's required by city code to have a pipe running from the tpr to within a few inches of the floor. Oddly, they don't care much if you have a drain for that pipe to run to...
- Wm

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William Morris wrote:

The requirement is there so that discharge of scalding water/steam from the T & P is less likely to strike someone standing nearby. Codes usually require that a "suitable" drain be provided for the discharge but the locals may be convenientally overlooking that. Jim
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Yeah, but run a leaking one to a drain?
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The TPR valve should -always- be run to a drain, code or no code. Just picture what happens if the valve opens and fails to close again (yes it happens). You now have an open connection to the service line that will continue to spew water until someone shuts it off. No drain?? Where do you think the water is going to go??
Harry K
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First off, local codes (read LOCAL) do not require the relief valve to be run to a drain. The code requires the pipe to be run to a point a few inches above the ground. Running the pipe to a drain is a plus.
Second, and more important(!), the question was who told the OP to run a leaking pipe to a floor drain. If the relief is leaking, there is a problem and running it to a floor drain will simply hide the problem. You need to learn how to read.
Oh, and yes, the relief valves do pop and run continuously. If it's in an older house with a 1.25 inch or a 1.5 inch floor drain (and it does happen, I'm sitting about 14 feet from a 1.5 inch floor drain), don't you think 65-120 psi will overpower the draining capacity of such a small drain?
While I'm at it, have you ever seen the pipe off a relief valve drain upwards? I see them almost daily...... New codes require there to be some way to drain the water off the seat of the valve.
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I'm curious. Just how do you know that no local codes don't do that?

What got your panties in a bunch? I posted a comment to others pointing out that just pointing a TPR overflow to the floor (or elsewhere) is not a good practice. If you think I mean to connect it to the drain, I don't. You must ahve an air gap and a blowing pipe into a drain will be notice enough. You seem to think that suddenly discovering water everywhere on the floor is a 'good thing'. As to reading, I do just fine, you don't do so well in the logic department tho.

Again your seem to think that a flooded floor is a 'good thing'. Yes it can overwhelm the drain so just let it blow eh??

So all -local- codes require that now??. Just how does pointing the pipe -up- drain the valve seat and just where is all that water spraying to??
Harry K
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Our local codes, you moron.

Brother, you ain't got a clue, do you? 'Pointing' the releif towards the floor is better than not piping it down at all.

or a hack 'plumber' comes in and reconnects the existing pipe the the new releif. That's when the drain from the releif comes in. That's what keeps the water off the seat of the releif.
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Ah, that is clear as mud. Because -your- codes don't that means -no codes do-? I can see it now as my local inspector downchecks my work. "but heatman's code doesn't require that". Your logic has a BIG hole in it.

And that comment is supposed to mean something in response to what I posted?? Logic man, logic. Of course it is better but it is not the -best- solution.

Well your first -personal attack (for no reason)- on me was to the effect that leading it to a drain was bad business. Gee, maybe that gave me the idea that you don't approve of it.

Try answering the question instead of going off into the bushes. Again, pointing the pipe -up- drains the valve seat just how? I have never seen a pipe pointing up that drains anything unless it is by siphon. Why do I think that you have read something into the code that isn't there?
Here is another question. Do you agree that the TPR valve should be piped to a drain (using an air gap of course)???
Harry K
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municipality....
understood what i was saying. I don't care if you do.

a moron, not to be confused with the Stormin Moron)? This has not been a personal attack, unless you are thin skinned enough to beleive it is..

releif into the tee and provide a way for the water to drain off, usually a 3/8" sink valve. This will allow the water to drain off the seat (providing it was installed at a slight downward pitch) with out spraying high pressure hot water all over a person that stands near the valve. Nibco makes an elbow that has a drain on it. To me, that looks a lot neater and I will take the rubber gasket out that seals it. That means there is no way the HO can seal the pipe off and let water sit on the seat. (of course, I don't do this if the water tank is in an area that can be damaged by water on the floor. I also explain all functions the the HO before I submit the bill and answer any questions.)

thread, Harry is refering to an air gap not as a special fitting, but an actual space between the end of the releif and the drain opening. That way you can see the water coming out the releif and know you have a problem.
If you have noticed, I have always referred to the fittings as a relief or relief valve instead of a 'TPR.' Do you know why that is?
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Make up your mind. Do -all- codes require this? In one place you say that no codes require it be piped to a drain, then you say that all codes require it to be piped vertically. Now just how you know that is a wonder.
No I don't as TPR is short for Temperature, Pressure, Relief (Valve). Correctly it should be TPRV but the shorthand is acceptable.
Thin skinned? In your very first reply you said I needed to be able to read? Not a personal attack?? Horse shit!.
Your only valid point about the pipe pointing up is to keep it from spraying on a person standing next to it. If pointed down it could still spray on the feet. As for draining the valve, a pipe pointing down does that quite well without all the monkey business.
Note that this whole think started with you complaining about me saying that it should be piped to a drain. Now you say you do it when possible. So just what -is- your problem?? By the way, you could knock off the personal attacks, it only makes you look stupid.
Harry K
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*not* harm someone. How it's piped is usually locally determined.

of the water. Do you have a clue what I am talking about?

I don't use language like that and I think it's vulgar and demeaning. You need to grow up and start reading what is written with an open mind. This has never beena personal attack and will never be in a public forum. One of the best rules of management is to praise in public and punish in private.

By the way, what exactly do you do for a living? It sure isn't mechanical contracting.

drain?" My comment to that was doing that without repairing the problem wasn't not the proper way to solve the problem. You then said something about an air gap. The thread went downhill from there.
I will agree that is *should* be piped to a drain. It's just that it's not always possible.
Harry, people like you don't need a keyboard. You think you are always right and hide behind the keyboard proclaiming your superiority to anyone that will listen. That superiority complex you have (like a mini Napoleon) gets magnified because you can hide behind a keyboard.
When you have 20 plus years in the mechanical field, you will have the right to say what you want. Until you can prove to me you have been in my field for enough years, you are still a moron.
I am done with this thread and will no longer respond to your idiotic comments. If you wish to continue this conversation, you may email me at my response address.
BTW, your TPR comments are wrong. I call it a relief because they relieve pressure in boilers and water heaters. I have never seen a boiler set up correctly that had a 'TPR' on it. Most boilers I work on have relief valves that open at 30 pounds. Even those are supposed to be (at least) piped to the floor. Piping a steam boiler relief to a floor drain can be a major waste of materials.
'nuff said. Have a good life Harry.
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One last thing.

You want to see personal attacks? Go to news:alt.hvac and you'll see some personal attacks. And except for one person, I don't do that.
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Humble respondent apologizes for opening a can of worms and causing a ****storm and promises not to do it again, if he can figure out how to ask a simple question without such result.
Now everyone take a deep breath and return to whatever it is you were taking apart before. And have a good week. I'm going to put an expansion tank on.
...phsiii
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If nothing else, phsiii, you helped provide some entertainment for the rest of us. :)
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I won't accept your apology because you don't need to give (or offer) one. Part of my job is to teach people. Some people don't want to be taught.
If you still wish to offer an apology, I will accept it. I still don't think it's necessary.
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So calling me a moron for only saying that it -should- (notice not must) be piped to drain is not a personal attak. While it was fun as a kid stirring up an ants nest to watch the activity, your amusement value has worn off. If you treat your customers the way you have been acting here, I would say you probably don't have a lot of repeat business...bye
Harry K
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Sears troubleshooting guy (they did the install, had a good sale on at the time I bought it). He was interesting: had to be 75, obviously been doing this since Hector was a pup. But he didn't figure out why it had just started, I did, so I felt smarrrt (as my kids would say).
...phsiii
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