Water heater Pressure Relief Valve open up

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Diehard

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The longer one just gives you more room for your wrench, I'd guess, but I welcome a more learned opinion.
That may be true but I saw one recently,(may have been on this or another forum) where the mounting of the relief valve was a few inches from the side of the tank due to some fittings(don't remember the fittings). That dictated a need for a longer probe to get it inserted sufficiently into the tank.
So it makes me think, there may be different requirements for probe lengths based on design of tank.
 
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bdmeyer

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Thank-You all. That's a habit that ya'll just broke for me. I'll be certain to pass it along also. (You guys are great)
 

RenewDave

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The “deep shank” units are extended for one reason. After the last energy efficiency upgrade to water heaters, the manufacturers put more insulation between the tank and skin. The deep shank t&p absorbs that. Whenever we service a water heater we change the t&p. It is the single most important safety device in your house. YouTube exploding water heaters.
 

bdmeyer

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I got my shiny new gauge in yesterday and installed it.
This morning I checked onit, and for the first time ever saw the water leaking while I watched.
I had just finished washing so the heater was still heating up the water. The water was coming out at a very slow trickle.
Yesterday, the pressure had been 'about' 40. This is what it looked like while the water heater was heating up.
is this normal when heating, or am I looking at more than just a simple T&P Valve replacement with this much pressure?


upload_2019-2-22_7-37-16.png
 

jeffmattero76

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I got my shiny new gauge in yesterday and installed it.
This morning I checked onit, and for the first time ever saw the water leaking while I watched.
I had just finished washing so the heater was still heating up the water. The water was coming out at a very slow trickle.
Yesterday, the pressure had been 'about' 40. This is what it looked like while the water heater was heating up.
is this normal when heating, or am I looking at more than just a simple T&P Valve replacement with this much pressure?


View attachment 19979
Not an expert, but I believe the water pressure inside a residence should be between 50 and 70 psi. Do you have a Pressure Reducing Valve on the incoming line from the street? If so, you may be able to adjust your water pressure there. If not. I believe you will need to get one installed. A PRV is a fairly large bell shaped structure that is usually inside the home, close to where the water line enters the house
 

bdmeyer

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I don't think I have one of those. I do have a manual cutoff in the garage.
Would the pressure still be considered high if, most of the time, that pressure gauge reads about 40? It only went up this morning after I washed. Yesterday, I ran every hot water faucet, shower, washer, dish washer for five minutes and the pressure never changed. This just happened this morning.
 

frodo

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take your gauge and walk outside
screw it on your outside hose bib

if you are having 150 psi in your system you need a pressure regulator valve

or you need to replace a faulty PRV

your pressure should not be more than 70 psi....50/60 is perfect
 

jeffmattero76

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take your gauge and walk outside
screw it on your outside hose bib

if you are having 150 psi in your system you need a pressure regulator valve

or you need to replace a faulty PRV

your pressure should not be more than 70 psi....50/60 is perfect
Frodo - if he is getting that high of a reading by putting the gauge on the water heater drain, but getting 40 from his hose bibb, does that indicate that his water heater temperature is set too high? Like I said, I am no expert, just trying to learn.
 

frodo

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Frodo - if he is getting that high of a reading by putting the gauge on the water heater drain, but getting 40 from his hose bibb, does that indicate that his water heater temperature is set too high? Like I said, I am no expert, just trying to learn.

trying to get answers to that question

in a previous post he said the temp was set at 24o degrees

i am trying to figure out if he needs a prv, with an expansion tank

first off, we need to know the city water pressure, and we need to know if that pressure spikes at night

if it does spike, he needs a prv

pressure should be the same at hose bid and water heater...with in a few plus /minus
 

Diehard

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If the pressure goes from 40 to 135 psi as shown, he must have something on the service preventing expansion.
I suggest pictures of everything from service entrance in, that looks like something.
And if there's an exterior water service vault/box where a PRV may be hiding.
 

frodo

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If the pressure goes from 40 to 135 psi as shown, he must have something on the service preventing expansion.
I suggest pictures of everything from service entrance in, that looks like something.
And if there's an exterior water service vault/box where a PRV may be hiding.

He did say it was intermittent
Some times, city water spikes in the middle of the night because lack of use
causing the whole system pressure to rise

lie you said, he either needs a prv or needs a replacement
 

Diehard

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Hopefully it's not possible to spike by that wide of a margin.

He also said, "most of the time, that pressure gauge reads about 40"
 

FishScreener

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I’d hazard a guess that he does have a Pressure Reducing Valve in the in-feed.

And, that it is preventing backflow from the house. As the water heater heats the water, it expands. I’d also hazard a guess that there isn’t an expansion tank on the hot water heater, and as the water heats up it is expanding, which increases the pressure, (which should be absorbed by the expansion tank), and the excess pressure is bleeding out the TPV.

Just like it is supposed to.

Solution: Install an expansion tank, and a new TPV.
 

Diehard

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I'd like to see pictures of anything and everything on that service line between the source and the water heater.
Particularly since the OP stated, "I don't think I have one of those." But I don't like to assume anything.

Yes we have been trying to determine if there was anything in the feed line all along but have been going off on tangents.
 

Mikey

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Wow! The water temp is typically set to 210!!!? That's seems incredibly hot.
That is incredibly hot, but that's the temperature at which the PRV releases. The temperature set for the WH is typically 120° and up. There's good science to suggest that you should set it at 140°.
 

FishScreener

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I install thermostatic mixer valves set to 120, and set the heater as high as it goes. The essentially gives you a 50% increase in tank capacity, and keeps the hot water hot enough to kill legionella.
 

Diehard

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I install thermostatic mixer valves set to 120, and set the heater as high as it goes. The essentially gives you a 50% increase in tank capacity, and keeps the hot water hot enough to kill legionella.
Any idea just how high the average temperatures of your installed water heaters go? Just Curious!
I believe 140 degrees F is the recommended high for killing legionella.
Of course above that is added fuel cost for the added standby losses.

To increase the effective tank capacity of 140 degree water by 50%, requires, I believe, something in the neighborhood of 190 degree water heater temp.
 
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Mikey

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From Cash Acme:
A water temperature of 120°F does not kill the Legionella bacteria; a hot water temperature of 140°F is required at which Legionellae dies in 32 minutes. Hence it is recommended that the water heater be set at a safe hot water temperature of 140°F. The Legionella disinfection range is 158 – 176 °F.
 

Diehard

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Well while we're on the subject of Legionella bacteria, the water heater isn't the only place in the home where it can grow.
"Just as important, to help reduce the risk of bacteria and legionnaires disease in your home:
  • If you have taps or showers you don’t use regularly, run them for 5-10 minutes at least once a month to clear the pipes.
  • Try to clean the outside of taps and shower heads at least once every three months.
  • Ensure there aren’t any places where water can stay still and build up bacteria."
The bacteria multiply where temperatures are between 20-45°C(68-113°F).
 

phishfood

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The various lengths of T&P valves are to accommodate the various thicknesses of insulation in the outer casing of various water heaters.

Water heaters vary very much. Verily, I say unto you.......
 
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