which TP valve next to PRV valve

[Bob from accounting]

What PSI TP valve should I find and install after the PRV
City pressure is 85, 60psi after the PRV.
I saw they made a 125 psi TP for water Heaters and storage tanks.
Let me know if you have any tips or suggestions on using a TP valve for this specific application and what PSI I should consider?

 

[James Henry]

There is no pop off required for what your describing.

 

[Sponsor]

 

[Jeff H Young]

a 125 psi pressure relief is sometimes employed on a area other than t and p at water heater often its used with a watts 210 at water heater but I dont know why the question certainly a pressure relief valve can go on the main under appropriate conditions

 

[Bob from accounting]

At what PSI do appliances and fixtures start to get overly stressed? ( we regulate to 60 psi)
If our PRV fails, would it be wise to have a relief valve as a fail-safe?

James, it seems like you may be saying that in my situation it would not matter as our City Max, at this time, is 85.

Jeff it seems like you might be saying it is not a bad idea to put one in and 125psi should be fine.

Did I interpret that correctly? I admit I was a bit foggy on this so forgive me if I am butchering your suggestion.

 

[Jeff H Young]

Hey bob,
It could be unnessesary likely unessesary if you have a t and p at water heater I would see little reason for it. dosent help much and a possible failure ( dripping down the road ) . nothing illegal about it

 

[James Henry]

I have never heard of a TP valve being used as a fail safe for a cold water line. Hence the word temperature in TP valve.

 

[Reach4]

At what PSI do appliances and fixtures start to get overly stressed?

Something more than 150 psi. You don't want to hit that, but that does not normally damage an appliance or fixture.

 

[Bob from accounting]

OK good to know,

Thanks for the help

 

[Jeff H Young]

I have never heard of a TP valve being used as a fail safe for a cold water line. Hence the word temperature in TP valve.

Me either they use a pressure relief valve and not a t and p there are posts and pictures on this forum wish I knew how to bring them up. one is captioned " california (la)plumbers service entrance pressure relief? I seen a lot of relief valves in los angeles plumbed similar

 

[Bob from accounting]

OK thanks for helping me sort this out.
I might settle on something like this.

https://www.supplyhouse.com/Zurn-P1000AXL-125C-Wilkins-125-PSI-Relief-Valve-Lead-Free?utm_source=google_ad&utm_medium=shopping_neutral&utm_campaign=Shopping_Neutral_HPLTV&gclid=CjwKCAiAoL6eBhA3EiwAXDom5u9a-zHBbkWdfqGNIQueac3BVKM4etRym8iaWHmpRHTiQ3IYTW7QMhoCKn0QAvD_BwE

 

[Jeff H Young]

sure thats fine. I dont know your reason for installing this but that is what is sometimes used to relief e pressure in excess of 125 psi

 

[Bob from accounting]

sure thats fine. I dont know your reason for installing this but that is what is sometimes used to relief e pressure in excess of 125 psi

I did not question this installation and assumed this was a risk mitigation feature.
However, you are right I suppose I am not sure if this is necessary.
If the PRV fails and the City pressure exceeds safe limits, it seems these would prevent pressure exceeding 125 to enter the homes, fixtures and appliances.
What are your thoughts on this? Does it seem this is not necessary?
Thanks for shedding some light on this. I would like to hear your thoughts so that when I speak to our plumber again I have more insight as to why we should not install this.
Thanks

 

[Reach4]

I would consider it undesirable. If this hypothetical overpressure occurs, do you want to be the one relieving the pressure through your water meter? If you did that, I would want that discharge to be into something with a loud water alarm, so that you can turn off the water.

There can be a reason for a 125 psi relief. Your T&P feeds onto the floor. You pipe the 125 psi relief to somewhere where you will notice, while not making a mess on the floor. One way this discharge happens is if your thermal expansion tank is not working properly.

 

[Jeff H Young]

Bob it dosent do anything that your tand p does at the water heater does. Im assuming you didnt plug off your tand p on the water heater? You do understand the pressure inside a water pipe at the water heater is the same as at a kitchen sink or anywhere in the system right? the only diferance being the t and p at waterheater would blow if the pressure or the temp got high one at the front of house wouldnt get affected by tempurature .
if you need a redundant pressure relief valve or dont have a t and p at water heater concider putting a relief valve at another area but dont plug one off at w/h unless you know what you are doing

 

[Bob from accounting]

Bob it dosent do anything that your tand p does at the water heater does. Im assuming you didnt plug off your tand p on the water heater? You do understand the pressure inside a water pipe at the water heater is the same as at a kitchen sink or anywhere in the system right? the only diferance being the t and p at waterheater would blow if the pressure or the temp got high one at the front of house wouldnt get affected by tempurature .
if you need a redundant pressure relief valve or dont have a t and p at water heater concider putting a relief valve at another area but dont plug one off at w/h unless you know what you are doing

Thanks Jeff and Reach.
You both have helped me so much in the past. So I take your comments with extra care.
I do have a 150 psi T&P on my personal WH, It never crossed my mind to plug my temp pressure relief valve. So no worries there.
The main PRV outside feeds multiple units within one shared building it feeds. I don't have control over everyone else's T&P valves. I assume they all work. However, putting a relief valve next to the PRV seemed like good insurance so that my water heater's T&P valve was not doing all the work (reliving pressure) for the entire building ( assuming their T&P vales did not work, which I assume they do work)

Based on this Pressure regulator valve and pressure relief valve setup, the water pressure would be relieved outside where the main 2" line comes into the building. This would be cold water, outside, next to a drain, next to the building's shutoff. All this is an economical backup to the PRV... Which is currently failing.

I am no plumber but this all seems like a good 35$ insurance plan, even if it was to just avoid a mess inside? Right?

I hate going against your help and all your years of insight, but after reading and discussing with others and you guys, the pros do seem to out weight the cons in this specific situation. Keep in mind this is how all the other 30 buildings are set up like this. Must be some rhyme or reason for it.

Thanks so much for your thoughts. If you have any other cons other than it being undesirable, and redundant to the home's T&P valve, I am going to take note and discuss it with my plumber further.
Thanks again,
Bob

 

[Jeff H Young]

Are you in Los Angeles County or city by chance? If the relief valve was 125 rather than standard 150 like one at W/H and the location the t and p was run to was undesireable or unsafe I could see the redundant relief valve as having a use. I dont agree with 35 dollars as a good insurance policy or even 5 bucks worth it plus your time or somebodys time.
I admit I dont know why people or possibly code in L.A. use them just seems like there are no "pro" argument other than a low cost just unnessesary waste but Im sure open to understand why I should install one, or why everyone should concider. If your neighbor didnt have any protection whatsoever your t and p is going to open and dribble out lowering the pressure to a safe 150 tops (or the other 30 in the neighborhood) . Im here to learn too