Water Heater Pressure Relief Valve

[MasterPlumbersKeymaster]

We were told to replace our pressure relief valve as our tank is leaking about 1 gal. per day, and the water gets cold quickly. My question is: To change the valve, do we need to turn off water, turn off gas, drain tank? The valve came with no instructions. Please advise.

[GuestParticipant]

A relief valve is the important safety device on your tank and it should be installed by a professional as it can be damaged by improper tools and piped incorrectly preventing safe operation. Sometimes dripping is caused by other problems.

If you must take on this responsibility and can not afford better service: The water should be drained to a point just below the valve after all power is turned off to the unit to prevent water from getting into the controls. Leave a tap open during replacement to prevent pressurization. Properly applied teflon tape is often used instead of pipe dope. Refill the system and flush all the bubbles from the system by running the taps before reapplying power and closing all taps. Make sure your piping is according to code to prevent insurance policy rejection after an occurance.

[GuestParticipant]

quote:

---

Originally posted by [email protected]:
We were told to replace our pressure relief valve as our tank is leaking about 1 gal. per day, and the water gets cold quickly. My question is: To change the valve, do we need to turn off water, turn off gas, drain tank? The valve came with no instructions. Please advise.

---

Kind Sir, since you use the passive
voice in your inquiry, “you were told” might one inquire by whom? A
T&P relief valve on a gas water heater would in no way account for
a lack of hot water if the leak is
one gallon per day. The average recovery on a gas water heater is
40 gallons per hour. Something else is wrong. You do need a pro.
Please make sure that the leak is from the relief valve and not the
tank itself or you will need a pump
and wet-vac shortly.

[johnwsParticipant]

There are a couple of unanswered questions. 1. Is this a problem that has just started? 2. How much hot water are you using ie. could you be using all the hot water in the cylinder before it has had a chance to recover?
When water is heated, it expands at a rate af about 3%, this would equate to about 1 gal for a 40 gal cylinder being heated from cold. .
I recommend you turn off the power to the cylinder turn on a hot faucet for approx 1-2 seconds and see if the valve starts to relieve again. If the water stops then it may only be operating as it should. If it doesn’t then follow the instructions of Harold and Lyebury and get a professional.

[Wallingford Plm+HtgParticipant]

Before you change anything check the water pressure.High pressure can cause this problem.

[SylvanLMPParticipant]

Hey Wall you are indeed a WEALTH of information GUY you are a CREDIT to NY State plummmmin

When you say check for “High pressure” are you saying 1000 PSI or more? Are we talking coefficient of expansion?

How do we know what is considered high pressure in his area?

Are you basing this statement on the NBBI Code or the ASME or the AGA/CS standards?

Don’t you think a Temperature & Pressure valve should also be checked for the actual temperature inside this tank? After all cant the probe be defective?

When you say Mr. Wall that the Pressure maybe to high are you checking static pressure or heated pressure Or the pressure when water is actually flowing?

Now suppose this gentleman did take a pressure reading of 149. PSI and if you know he has a 50 gallon heater PLEASE Wall tell him What size expansion tank he will need considering his in coming pressure is only 65 PSI

Now considering your a master plumber in Up State NY you should be able to tell him how to test this device as per ASME section IV and you being a full Plumber please tell this gentleman how often this T&P should be tested and or replaced?

I am considering of giving up posting on this list and I hope you are willing to take it on as the head honcho so MASTER PLUMBER please explain what else can cause the above problems?

You may want to tell him about the design difference of a safety and a relief valve.
Thank you Wall you are now the unofficial EXPERT now please give this gentleman a proper answer not say “DUH check pressure.” If you cant ILL be happy to AGAIN explain about the various code requirements. You GO Wall here is your chance of showing these folks what a REAL New York State guy knows.

Harold this should be intreasting huh Rod your brilliant LOL

[GuestParticipant]

Water getting cold quickly can be a sign of a failed dip tube or a water heating element or firing problem, also. The tank may require an expansion tank. Just changing parts without knowing the real problem can start a long chain of replacements until the cause is known.

[SylvanLMPParticipant]

quote:

---

Originally posted by Wallingford Plm+Htg:
Before you change anything check the water pressure.High pressure can cause this problem.

---

I once was told by an apprentice that a T&P meant Temperature and Pressure

Now Wall I know your a top notch plumber from the EMPIRE State so possibly this helper is wrong and all one needs to do is CHECK pressure and not the temperature huh?

Of cause he was only doing plumbing for 3 days and didn’t know about the fact that there are several possibilities like thermo expansion where no provisions for this expansion.

There could also a defective high limit operating controller thus water reaching 210 Degree F would also cause the relief valve to discharge Or if this is well water will too much aeration the escaping bubbles could compress and thus reach the set point of 150 PSI rating of most of these devices.

Thankfully you gave a short to the point answer and this is why I would never listen to a person with only 3 days in the field.

I cannot thank you enough for your explanation. Perfect answer.

[GuestParticipant]

Quote:

Originally posted by SylvanLMP:

I am considering of giving up posting on this list and I hope you are willing to take it on as the head honcho

I only hope that you are seriously thinking of leaving this site, Sylvan.The sooner the better. Au Revoir!, So long!, Adios, Shalom!, Ciao!, Sayonara!, Hasta Luego!, Good Riddence!
By the way, Who made you the “Head Honcho”. Oh I forgot, this is you own personal website!The rest of us peons must wallow in your reflected glory! PLease don’t disapoint us, Sylvan. Leave! And the sooner the better!!.

[Wallingford Plm+HtgParticipant]

Are you still mad about the frostless toilet?You come to this site just to try to impress people with all your greatness.I’m not impressed at all.you should really try to use your knowledge to help people instead of attacking.Try upping your dose of Prozac.

[GuestParticipant]

Dear Wall,
Good answer on the water pressure! Several years ago our area installed new water mains.
This increased standing pressure to 300+ psi.These pressure affect everything!!

[Author]

Posts