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  1. #1
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    Default Double the protection!

    Two is always better than one, right?

    TPRs.jpg

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  2. #2
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    Default Re: Double the protection!

    Somebody should have their pipe wrench confiscated.

    In fact, something like that should be a criminal offense. Building a pipe bomb in the basement. It's terrorism against your own family. Darwinism?





    John Kogel, RHI, BC HI Lic #47455
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  3. #3

    Default Re: Double the protection!

    Okay, I'm gonna get slammed, but I'm newer at this than most of you. Could you please explain what this is? I see gas piping that appears to be going into a furnace housing. But what, exactly, is going on here?

    Welmoed Sisson
    Inspections by Bob, LLC, Boyds, MD
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    Default Re: Double the protection!

    Quote Originally Posted by Welmoed Sisson View Post
    Okay, I'm gonna get slammed, but I'm newer at this than most of you. Could you please explain what this is? I see gas piping that appears to be going into a furnace housing. But what, exactly, is going on here?
    ..........it' a P&T relief valve improperly (dangerously) piped via a nipple to a second P&T........Greg


  5. #5

    Default Re: Double the protection!

    Ah! Now I see it. Thanks very much. Yeah, that's pretty dumb. For some reason I saw black pipe and thought "gas" and failed to recognize the PT valve. I see the tag for the second valve but not the valve itself.

    Welmoed Sisson
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  6. #6
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    Default Re: Double the protection!

    Quote Originally Posted by Gregory Booth View Post
    ..........it' a P&T relief valve improperly (dangerously) piped via a nipple to a second P&T........Greg
    Greg - Why do you think that this is dangerous?


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    Default Re: Double the protection!

    Not Greg but I also know that this is dangerous. PRV one is under pressure, PRV2 is not, So the first little blast from PRV1 pressurizes the pipe. Now there is pressure on the outer side of PRV1, so it will not blow at 150 PSI because the pressure is equal on both sides.
    Moisture trapped in the pipe will rust the black steel and that rust will clog the valves.

    No question, it interferes with the operation of a safety device.

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  8. #8
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    Default Re: Double the protection!

    Am I looking at an illusion, as it looks like the first T&P is in the open position? Was the first one leaking and this was their fix, add a second one and leave the first one open? Itís still wrong.

    One possible danger is having a safety device after a safety device that is supposed to react as quickly as possible. When the first one opens it will fail to quickly relieve the pressure as the second device will block it until it reaches pressure, fail to work properly, or fail to open at all. You are increasing the chances of a faulty valve being in the line as they can stick and being stuck shut = bomb. At least with one there is a chance it will be forced open, but with two the odds go way down.

    Also, it is a violation of the product install, can't have any other valves on the T&P line, just open pipe.



  9. #9
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    Default Re: Double the protection!

    Quote Originally Posted by Jim Abram View Post
    Greg - Why do you think that this is dangerous?
    Not Greg either, but the T&P relief valve serves two purposes: a) pressure, which John addressed; b) temperature and the temperature sensing prob is not within the top 6" of water as required. The temperature sensing probe is not in any water until the first T&P opens, then that water would have to heat up sufficiently open the second T&P valve.

    Yes, that is quite unsafe and dangerous.

    Quote Originally Posted by Mike Kleisch View Post
    Am I looking at an illusion, as it looks like the first T&P is in the open position? Was the first one leaking and this was their fix, add a second one and leave the first one open? Itís still wrong.
    The first is closed, the rounded end of the operating lever on visible to the right of the shaft, if the lever was up to open the valve that end would be against the top of the T&P pushing the valve open.

    I also suspect the first T&P was leaking and someone not knowing why the valve was there figured they could stop the leak by adding a second T&P ... and it probably did stop the leak.

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  10. #10
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    Default Re: Double the protection!

    The first TPR valve was actively leaking at the inspection.

    By the way, someone mentioned 150 psi. This is a boiler, so 30 psi would be the max.

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  11. #11
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    Default Re: Double the protection!

    Quote Originally Posted by Jerry Peck View Post
    Not Greg either, but the T&P relief valve serves two purposes: a) pressure, which John addressed; b) temperature and the temperature sensing prob is not within the top 6" of water as required. The temperature sensing probe is not in any water until the first T&P opens, then that water would have to heat up sufficiently open the second T&P valve.

    Yes, that is quite unsafe and dangerous.


    Jerry - This is not a T&P valve. This is pressure relief only. Now why is it dangerous?


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    Default Re: Double the protection!

    Quote Originally Posted by Jim Abram View Post
    Jerry - This is not a T&P valve. This is pressure relief only. Now why is it dangerous?
    Jim,

    Which one is not a T&P (is pressure only), what makes you think so, and why do you think that a pressure only would not make that installation dangerous?

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  13. #13
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    Default Re: Double the protection!

    Quote Originally Posted by Jerry Peck View Post
    Jim,

    Which one is not a T&P (is pressure only), what makes you think so, and why do you think that a pressure only would not make that installation dangerous?

    Jerry - You are the one that stated that it was dangerous. Now back it up.

    Both devices appear to be Pressure relief only from a review of the product specifications.


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    Default Re: Double the protection!

    Quote Originally Posted by Jim Abram View Post
    Jerry - You are the one that stated that it was dangerous. Now back it up.

    Both devices appear to be Pressure relief only from a review of the product specifications.
    "Both devices appear to be Pressure relief only from a review of the product specifications."

    That is what you said. Now back it up - provide the product specifications you are referring to.

    With your product specifications I will have supporting documentation to back up stating that it is dangerous.

    If they are combination temperature and pressure relief valves they are dangerous and installed improperly.

    If they are pressure only, they are installed improperly and dangerous because there would not be the required temperature relief valve - you are saying that they are both pressure only, which would be incorrect and unsafe, and dangerous ... surely you have enough knowledge and smarts to know that and understand that - if not, let me know, that would clear a lot of things up.

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  15. #15
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    Default Re: Double the protection!

    Quote Originally Posted by Jerry Peck View Post
    "

    If they are pressure only, they are installed improperly and dangerous because there would not be the required temperature relief valve - you are saying that they are both pressure only, which would be incorrect and unsafe, and dangerous ... surely you have enough knowledge and smarts to know that and understand that - if not, let me know, that would clear a lot of things up.

    Jerry - Nice fake and entirely incorrect .


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    Default Re: Double the protection!

    Quote Originally Posted by Jim Abram View Post
    Jerry - Nice fake and entirely incorrect .
    Jim,

    YOU said they were pressure only - show us all that they are pressure only.

    It really is that plain and simple, Jim, when you claim something is what you say it is, if questioned (and we question each other all the time) then you need to be able to show why you think it is what you said it was - so ... show us why you say it is a pressure only valve.

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    Default Re: Double the protection!

    Quote Originally Posted by Jerry Peck View Post
    Jim,

    YOU said they were pressure only - show us all that they are pressure only.

    It really is that plain and simple, Jim, when you claim something is what you say it is, if questioned (and we question each other all the time) then you need to be able to show why you think it is what you said it was - so ... show us why you say it is a pressure only valve.
    And then tell us all what you would report, because that is what this is all about, inspecting for a home buyer.

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  18. #18
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    Default Re: Double the protection!

    Quote Originally Posted by John Kogel View Post
    And then tell us all what you would report, because that is what this is all about, inspecting for a home buyer.
    @ John Kogel - "In fact, something like that should be a criminal offense. Building a pipe bomb in the basement. It's terrorism against your own family." Seems to be an excessive response. Is it accurate? I do not think so.What do you hope to accomplish with the overstating of this condition.

    This is simply a non professional repair . Will it work correctly ? Maybe . Is it a hazard or bomb as claimed ,Unlikely.

    Simple advice to home buyer. "Unusual modification of boiler pressure relief components . Advise that a technician review and appropriately repair."

    BTW - The valves appear to be standard Watts 30 psi PR valves . The outboard valve is identified as a Watts 335. The inboard valve is older and does not appear in current catalogs of available equipment. Boilers do not have T&P valves as a rule.



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    Default Re: Double the protection!

    My understanding is that the valves used on boilers are pressure relief valves only as the boiler should have a high temperature limit switch/cutoff incorporated into the boiler itself. And only water heater tanks used the temperature/pressure relief valves. I have looked at the tags on these valves at times and am pretty sure recall seeing ones that stated they were pressure relief only.....but don't hold me to that. I'll have to remember to see what the valve tag says on the next boiler I see.

    "It takes a big man to cry. It takes an even bigger man to laugh at that man". - Jack Handey

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    Default Re: Double the protection!

    Quote Originally Posted by Jim Abram View Post
    *BTW - The valves appear to be standard Watts 30 psi PR valves . The outboard valve is identified as a Watts 335. The inboard valve is older and does not appear in current catalogs of available equipment. Boilers do not have T&P valves as a rule.[/COLOR]
    Jim,

    Let's say that both are only pressure relief valves, where do you get your "boiler" from? It looks like a water heater to me - did I miss that in a post? I may have.

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    Default Re: Double the protection!

    Quote Originally Posted by Jerry Peck View Post
    Jim,

    Let's say that both are only pressure relief valves, where do you get your "boiler" from? It looks like a water heater to me - did I miss that in a post? I may have.
    #10 post.
    Boiler.

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    Default Re: Double the protection!

    Quote Originally Posted by John Arnold View Post
    #10 post.
    Boiler.
    John,

    Thank you, so we are referring to a boiler which has two pressure relief valves.

    And Jim does not think that two pressure relief valves is (or could be) dangerous?

    Maybe Jim can explain his thinking to us so that we too will understand why two pressure relief valves is okay, albeit unconventional?

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  23. #23
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    Default Re: Double the protection!

    I see the 2nd valve as no different than an end cap on the exhaust tube that will prevent the proper operation of the 1st valve. I would think that to get both valves to open the way they are intended would require much more than the 30 psi rating of an individual valve.

    "It takes a big man to cry. It takes an even bigger man to laugh at that man". - Jack Handey

  24. #24
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    Default Re: Double the protection!

    Quote Originally Posted by Nick Ostrowski View Post
    I see the 2nd valve as no different than an end cap on the exhaust tube that will prevent the proper operation of the 1st valve. I would think that to get both valves to open the way they are intended would require much more than the 30 psi rating of an individual valve.

    Nick - First this is a very unusual situation. I had never seen it before and it is unlikely that I will see it again.
    Out of curiosity, I ran a test on this configuration this AM with two new valves . Inboard valve opened at 32 PSI . Pressure in downstream pipe increased to 32 . Outboard valve opened immediately . This is what I suspected would happen. The valve is just a spring loaded spindle. Pressure will open the spring and discharge the pressure.


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    Default Re: Double the protection!

    Quote Originally Posted by Jim Abram View Post
    Nick - First this is a very unusual situation. I had never seen it before and it is unlikely that I will see it again.
    Out of curiosity, I ran a test on this configuration this AM with two new valves . Inboard valve opened at 32 PSI . Pressure in downstream pipe increased to 32 . Outboard valve opened immediately . This is what I suspected would happen. The valve is just a spring loaded spindle. Pressure will open the spring and discharge the pressure.
    Two new valves open nicely. Now load that thing up with rust and wait 10 years and tell us that it is perfectly safe.

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  26. #26
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    Default Re: Double the protection!

    Quote Originally Posted by John Kogel View Post
    Two new valves open nicely. Now load that thing up with rust and wait 10 years and tell us that it is perfectly safe.
    The general recommendation is to replace PR valves at 5 year intervals. Rust is an age related deficiency not a configuration deficiency.


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    Default Re: Double the protection!

    Quote Originally Posted by Jim Abram View Post
    The general recommendation is to replace PR valves at 5 year intervals. Rust is an age related deficiency not a configuration deficiency.
    I`m having a difficult time finding that requirement or recommendation on the Watts site, would you please post that, thanks.

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  28. #28
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    Default Re: Double the protection!

    Quote Originally Posted by Jerry Peck View Post
    I`m having a difficult time finding that requirement or recommendation on the Watts site, would you please post that, thanks.
    @ Jerry Peck - "It really is that plain and simple, Jim, when you claim something is what you say it is, if questioned (and we question each other all the time) then you need to be able to show why you think it is what you said it was - so ... show us why you say it is a pressure only valve.'

    Jerry - Still waiting for you to show why you claim this condition is dangerous.







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    Default Re: Double the protection!

    Quote Originally Posted by Jim Abram View Post
    The general recommendation is to replace PR valves at 5 year intervals. Rust is an age related deficiency not a configuration deficiency.
    Quote Originally Posted by Jerry Peck View Post
    I`m having a difficult time finding that requirement or recommendation on the Watts site, would you please post that, thanks.
    Quote Originally Posted by Jim Abram View Post
    @ Jerry Peck - "It really is that plain and simple, Jim, when you claim something is what you say it is, if questioned (and we question each other all the time) then you need to be able to show why you think it is what you said it was - so ... show us why you say it is a pressure only valve.'

    Jerry - Still waiting for you to show why you claim this condition is dangerous.




    And that's all you have? Nothing to support your assertion that someone somewhere recommends those pressure relief valves be replaced every 5 years.

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    Default Re: Double the protection!

    Quote Originally Posted by Jim Abram View Post
    Jerry - Still waiting for you to show why you claim this condition is dangerous.

    I'm not Jerry But I'll try, not that you'll understand it.
    The first pressure valve releases at 150 PSI ( or whatever)
    The second Does not release until 150 PSI (or whatever)
    The two in series will not release until 300 PSI
    I doubt the vessel is approved for 300 PSI.

    Last edited by Rick Cantrell; 03-04-2014 at 11:11 AM.
    ' correct a wise man and you gain a friend... correct a fool and he'll bloody your nose'.

  31. #31
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    Default Re: Double the protection!

    Quote Originally Posted by Rick Cantrell View Post
    [QUO
    Jerry - Still waiting for you to show why you claim this condition is dangerous.
    I'm not Jerry But I'll try, not that you'll understand it.
    The first pressure valve releases at 150 PSI ( or whatever)
    The second Does not release until 150 PSI (or whatever)
    The two in series will not release until 300 PSI
    I doubt the vessel is approved for 300 PSI.[/QUOTE]
    Rick - Interesting theory but it does not work like that . Disproved it yesterday. These are just a spring loaded spindle. There is no scientific basis to double the expected release level.

    BTW - These are 30 PSI relief valves .


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    Default Re: Double the protection!

    .......Jim, no matter how you spin it, it's an inappropriate repair for a leaking P&T (or P) valve. The continued leak-by of the first valve may well "gum-up" its design and render it non-functional. Why are you working so hard to defend a dangerous (even if potentially remote) situation?.........Greg


  33. #33
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    Default Re: Double the protection!

    Quote Originally Posted by Gregory Booth View Post
    .......Jim, no matter how you spin it, it's an inappropriate repair for a leaking P&T (or P) valve. The continued leak-by of the first valve may well "gum-up" its design and render it non-functional. Why are you working so hard to defend a dangerous (even if potentially remote) situation?.........Greg

    Greg - Not defending at all . Just discussing.
    You were quick to call it dangerous . Did you just make that up or is there some basis in fact for that claim.


  34. #34
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    Default Re: Double the protection!

    I think this really comes down to the purpose of the valve which is just pressure relief (assuming it is just a pressure relief valve). It's purpose is to exhaust water in the event of an excess pressure buildup to prevent the boiler or risers from bursting or rupturing. The real danger would be excess temperature buildup and superheated water which would be the result of a faulty limit control. I've seen a few boilers where the temperature gauge rose to 220-230 degrees. I was pretty nervous just being around those boilers until the temperature level decreased.

    But getting back to the two valves being installed and whether or not it is hazardous, I'm not sure it is or is not but one thing is sure......it definitely isn't right. Put two TPR valves on the same exhaust line for a water heater and then I say absolutely a hazard.

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    Default Re: Double the protection!

    Quote Originally Posted by Jim Abram View Post
    Greg - Not defending at all . Just discussing.
    You were quick to call it dangerous . Did you just make that up or is there some basis in fact for that claim.
    ........real-life, personal, on-site, in-person, hands-on experience has show me dribbling P&T (and P)valves that are frozen shut and INOPERATIVE and therefore, dangerous.....Greg


  36. #36
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    Default Re: Double the protection!

    Quote Originally Posted by Gregory Booth View Post
    ........real-life, personal, on-site, in-person, hands-on experience has show me dribbling P&T (and P)valves that are frozen shut and INOPERATIVE and therefore, dangerous.....Greg

    Pressure relief valves that are frozen shut and inoperative is not the topic.
    Two pressure relief valves in series is the topic . Why is that dangerous?


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    Default Re: Double the protection!

    Quote Originally Posted by Jim Abram View Post
    Pressure relief valves that are frozen shut and inoperative is not the topic.
    Two pressure relief valves in series is the topic . Why is that dangerous?
    ........sigh! In this instance the first valve is leaking, and a second valve was added, in series, as a method of repair. Left in place (leaking) the first valve can accumulate crud and "freeze" closed. Further discussion with you on this topic is time I can't afford to waste - you're welcome to the last word......Greg


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    Default Re: Double the protection!

    Quote Originally Posted by Gregory Booth View Post
    ........sigh!
    .
    Further discussion with you on this topic is time I can't afford to waste - you're welcome to the last word......Greg
    I've felt the way with most, if not all, of my discussions/debates with Jim.

    The problem is that leaves incorrect information as the last information posted.

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    Default Re: Double the protection!

    Quote Originally Posted by Welmoed Sisson View Post
    Okay, I'm gonna get slammed, but I'm newer at this than most of you. Could you please explain what this is? I see gas piping that appears to be going into a furnace housing. But what, exactly, is going on here?
    And you are a home inspector?


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    Default Re: Double the protection!

    Quote Originally Posted by Jim Abram View Post
    ... Out of curiosity, I ran a test on this configuration this AM with two new valves . Inboard valve opened at 32 PSI . Pressure in downstream pipe increased to 32 . Outboard valve opened immediately . This is what I suspected would happen. The valve is just a spring loaded spindle. Pressure will open the spring and discharge the pressure.
    This is one way it could work, and the way it will work if both valves trip at the same pressure or valve 2 trips at a lower pressure than v1. However, it could work another way if v2 did not pop at 32, but say 34. In the case of a spring loaded valve that resets, v1 will close when the pipe is pressurized to 32 as there is no pressure differential across the valve at all; valve 2 will not open since it needs a couple more pounds to trigger.
    In this condition the tank pressure must reach 64 to again cause 32 pounds of differential across v1.

    Combining devices in series can produce very different results by changing the performance of one device only slightly. This installation MIGHT work just fine but is potentially very dangerous.

    I like and applaud your idea of testing. However, we all need to remember that while a test proves something can happen a particular way, it does not prove it can't happen another way. Else, Russian Roulette would be a very different game.


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    Default Re: Double the protection!

    Quote Originally Posted by William Heuberger View Post
    And you are a home inspector?
    Really? This is your first post? I hope your future posts, if any, are more constructive.

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    Default Re: Double the protection!

    Quote Originally Posted by Jim Abram View Post
    I did have that thought. The function of the valves tested did not change due to back pressure. The pressure between v1 and V2 did not effect the trigger as the spring is enclosed in the valve and not subjected to back pressure . The highest pressure observed was 33 PSI.

    I also do not see a brief release of 64 psi as very dangerous.
    OK, so I think you are saying that the design of the release valve is such that it trips on the difference between tank pressure and atmo pressure outside of the attached pipe, not pressure inside the pipe. That is logical, and does indeed improve the situation considerably.

    The possibility of dangerous failure is still greater with two valves than one: Obviously, any single valve can fail and create a dangerous situation. The odds of this are supposed to be very low, assuming the replacement schedule on the valve is followed. Having two valves in series means either valve failing causes the whole release system to fail. The odds of a single valve failing to operate as designed go up significantly if the second was added because the first was obviously failing in some way (leaking).

    We know v1 leaked and suspect they added v2 to contain the leak rather than replacing v1 (previous discussion). Why not just replace v1? Maybe v1 was rusted into position. More likely I think is that this would require them to shut down the device while they did the swap, and this was too much trouble. Not an encouraging assessment.


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    Default Re: Double the protection!

    Quote Originally Posted by John Arnold View Post
    Really? This is your first post? I hope your future posts, if any, are more constructive.
    What was wrong with my post? The original question shows what is wrong with the home inspection business. Untrained individuals making inspections that the general public rely upon to be valid.


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    Default Re: Double the protection!

    Quote Originally Posted by William Heuberger View Post
    What was wrong with my post? The original question shows what is wrong with the home inspection business. Untrained individuals making inspections that the general public rely upon to be valid.
    Settle down, eh? On a cellphone or tablet, the pics are not always clear. Sometimes the pic sends a confusing message, like the glass is half full instead of half empty. It does not reflect in any way on that person's ability as an inspector, where they are working in the real world.
    I won't argue with the presence of untrained home inspectors, but Welly isn't one of those.

    John Kogel, RHI, BC HI Lic #47455
    www.allsafehome.ca

  45. #45
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    Default Re: Double the protection!

    Quote Originally Posted by Rick Cantrell View Post
    I'm not Jerry But I'll try, not that you'll understand it.
    The first pressure valve releases at 150 PSI ( or whatever)
    The second Does not release until 150 PSI (or whatever)
    The two in series will not release until 300 PSI
    I doubt the vessel is approved for 300 PSI.
    Quote Originally Posted by Jim Abram View Post
    Rick - Interesting theory but it does not work like that . Disproved it yesterday. These are just a spring loaded spindle. There is no scientific basis to double the expected release level.

    BTW - These are 30 PSI relief valves .
    I'll be polite and just say, "Your testing is flawed", that or you are, shall I say, misstating the facts.
    As I said, not that you would understand.

    ' correct a wise man and you gain a friend... correct a fool and he'll bloody your nose'.

  46. #46
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    Default Re: Double the protection!

    Quote Originally Posted by Jim Abram View Post
    I did have that thought. The function of the valves tested did not change due to back pressure. The pressure between v1 and V2 did not effect the trigger as the spring is enclosed in the valve and not subjected to back pressure . The highest pressure observed was 33 PSI. ...
    (Follow up to previous reply)
    Your understanding of the spring not being subject to back pressure is incorrect.
    (Relief valve - Wikipedia, the free encyclopedia) (Description of valve, including valve cutaway drawing.)

    The design of the valve requires that the pipe (if any) attached to the outlet is open on the other end and has zero pressure. If this pipe has pressure, the nominal pressure to open the valve is the spring pressure PLUS the pipe pressure, but this nominal pressure is not entirely predictable and much greater pressure can be generated. In fact, more pressure can be experienced in the pipe and tank during release than the tank had before the valve triggered!

    Assuming the release pressure of the both valves is set to 50 pounds. The pressure on v1 causes it to open, and the pipe begins to pressurize. Once the pipe pressure reaches 10 to 20 pounds v1 will begin to close (assuming normal "blowdown" setting, the pressure at which the valve will reset). However, it may or may not close fully before v2 opens. (Depends on speed of closure, volume of pipe, length of pipe, volume of release through v1, etc.) If it does fully close, pressure will need to rise again to 50 + (pipe pressure). This can pulse-charge the pipe until sufficient pressure is reached to open v2.
    It's possible (becoming more likely with short, low-volume pipes) for v2 to open with less than it's set pressure when a pressure wave slams into it from the opening of v1. The energy of the wave-front can significantly exceed the static pressure of the tank.
    Once both are open they may both stay open (with sufficient pressure and flow from the tank) or flutter with an unpredictable interaction as one or the other closes, each closure affecting the other valve. This flutter can be even more dangerous than the increase in nominal pressure since the peak pressure in the waves can be much more... think "The mother of all water hammer effects."

    In this particular case, complications are that v1 is leaking, possibly so much that v2 effectively becomes the pressure release... unless it releases, in which case v1 may or may not fully open, or may flutter, or may release rust or other crud to impair v2.

    So, I retract my previous post which was based on the claim that the valve triggers on the difference between atmospheric pressure and tank. This is not true unless the pipe is both short an open at one end. The installation is inherently very, very dangerous, with the exact failure mode unpredictable.

    Last edited by gary carroll; 03-04-2014 at 08:57 AM.

  47. #47
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    Default Re: Double the protection!

    I contacted the horse's mouth yesterday and am awaiting a reply ... when in doubt I go to the horse's mouth and check the gums and teeth before fully committing to the horse.

    Sometimes a have to poke the horse a few times to wake it up before what I need.

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

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    Default Re: Double the protection!

    Here's a couple of pics of a water heater TPRV, closed and opened manually. Not the same as a boiler PRV, but the same general principles are there.

    Nothing so far has changed my first statement that this is a dangerous situation, except that I was incorrect about the release pressures.

    ***IMPORTANT*** You Need To Register To View Images ***IMPORTANT*** You Need To Register To View Images
    John Kogel, RHI, BC HI Lic #47455
    www.allsafehome.ca

  49. #49
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    Default Re: Double the protection!

    Well, just for fun, I read through our Boiler Code looking at safety valve requirements and they all require no shut-off valves or other restriction valves on the line.

    I also looked up the installation for a random Relief Valve and it said:

    No shutoff valve or other connections or restrictions are permissible between the boiler (or tank) and the safety relief valve.

    Thus, according to our code and the instructions for this relief valve you can't have two relief valves on the same line.


    1 - You have a violation of code, a restriction valve on the line, before or after the relief valve.

    2 - You have a violation of the product installation, a restriction between the boiler and relief valve.

    I would not allow it, and see it as a hazard too, and the above tells me code and instructions see it as a hazard.



  50. #50
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    Default Re: Double the protection!

    Quote Originally Posted by Mike Kleisch View Post
    Well, just for fun, I read through our Boiler Code looking at safety valve requirements and they all require no shut-off valves or other restriction valves on the line.

    I also looked up the installation for a random Relief Valve and it said:

    No shutoff valve or other connections or restrictions are permissible between the boiler (or tank) and the safety relief valve.

    Thus, according to our code and the instructions for this relief valve you can't have two relief valves on the same line.


    1 - You have a violation of code, a restriction valve on the line, before or after the relief valve.

    2 - You have a violation of the product installation, a restriction between the boiler and relief valve.

    I would not allow it, and see it as a hazard too, and the above tells me code and instructions see it as a hazard.
    Quote Originally Posted by Jim Abram View Post
    How do you get to hazard ?
    Jim
    How/ why do you think it's not a hazard?

    I think you made a statement and now you've taken a stand to defend that statement.
    Everyone here has made a statement that was shown to be incorrect, nothing wrong with. But to continue to defend an incorrect statement does not help your creditably.
    Before you continue to defend your statements you should consider how this makes you look to others. If you have evidence that supports your view then show it to us.
    I've been wrong before, and likely will be wrong again. But when I'm wrong I found that nobody gloated over it or belittled me.
    It's a violation of code for a reason.
    This is a hazard, plain and simple as it can be.

    ' correct a wise man and you gain a friend... correct a fool and he'll bloody your nose'.

  51. #51
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    Default Re: Double the protection!

    Quote Originally Posted by Jim Abram View Post
    If you take a look at the cutout sketch you posted , it is obvious the spring pressure and pipe pressure are not cumulative. Interesting thought though.
    Valve manufacturers say otherwise.

    http://sache.org/beacon/files/2013/0...5-Beacon-s.pdf

    This is a more detailed description of operation and diagram of a typical valve from the Center for Chemical Process Safety that specifically addresses this issue. Quoted from the document: "In a conventional relief valve the bonnet pressure is equal to the downstream pressure...".

    The bonnet is the part of the valve that houses the spring. Pressure exerted on the seal is the combination of spring and ambient pressure in the bonnet acting on the bellows. Normally, ambient pressure in the bonnet is atmospheric since the discharge pipe is open on the other end, and thus we need only consider spring pressure.
    However, if the bonnet is pressurized by back pressure (as would be present with any restriction in the downstream pipe) that pressure also operates on the bellows cumulatively with the spring pressure. This is as I described above.

    A vented bonnet may be employed to avoid this problem where some restriction is unavoidable (long pipes, or pipes discharging into manifolds) but this is not a typical valve, and not what you would expect to find anywhere other than industrial applications. In particular, I would not expect whoever added the second valve to modify the first to have a vented bonnet. If they did, they would almost certainly be leaking through the vent to the exterior. Some vent leakage is normal when you use this type of valve, and if the valve is already leaking it would be increased.


  52. #52
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    Default Re: Double the protection!

    Quote Originally Posted by Jim Abram View Post
    The effect of back pressure working as cumulitive pressure is possible but not with valves of this design. It appears that the bonnets on these valves may be vented, ( by design or default is unknown), which would eliminate the issue entirely.The engineering handbook for Crosby valves TP -v300 c.1997 only attributes a minor increase is release pressure due to a number of prv in series but only for non vented valves.
    Interesting discussion but, it has gone on way too long for a very unusual condition.Obviously the installation is not correct and should be repaired . Those who claim it is dangerous or a hazard really need to do some research to justify that position.Isn't stating it is incorrect or a deficiency enough?
    I see no evidence that the bonnets are vented. A vent would require a warning sign and drain path, neither of which seem to be present. Such venting would not be at all normal. Why do you think they are vented?
    You say back pressure is not cumulative on valves of this design, cite the Crosby engineering handbook, and say only a minor increase in pressure would be experienced. I quote from Crosby Engineering Handbook, Chapter 2, Design Fundamentals: "A review of the force balance on the disc (Figure F2-2 on page 2-2) shows that the force of fluid pressure acting on the inlet side of the disc will be balanced by the force of the spring plus whatever pressure exists on the outlet side of the valve." (emphasis mine). Later: "...the pressure at which the valve opens will change as the back pressure changes. This variation may cause the opening pressure to vary beyond allowable limits."
    The handbook seems to say exactly the opposite.
    I don't think you deliberately misstated, I think you are misinterpreting the portions of the handbook that discuss multiple valves. The tables refer to multiple valves venting in parallel to a common manifold. Multiple relief valves in series is specifically forbidden by both code and handbook and thus there are no tables for this.
    (http://www.isibang.ac.in/~library/on...ghandbook3.pdf)

    "Those who claim it is dangerous or a hazard really need to do some research to justify that position" - I am a design engineer with over thirty years experience of systems analysis. I contacted two manufacturers to ask their opinions. I cited professional organization recommendations. I posted the handbook for the brand of valve you specifically cited, though it's not clear this is the brand of the valve in question.
    I believe this constitutes research to support my opinion.
    In your defense, you did an actual, real test that gave results that could be interpreted to support your position. I explained why I believe this result may be misleading.

    I say again that in my opinion this sort of installation is against code, against the manufacturers clear instructions, and is dangerous from an engineering standpoint. It may not actually fail in a dangerous manner, but the same could be said of no release valve at all.

    I do agree that we can end this. We have a similar conclusion as to what should be done.


  53. #53
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    Default Re: Double the protection!

    Quote Originally Posted by Jerry Peck View Post
    I contacted the horse's mouth yesterday and am awaiting a reply ... when in doubt I go to the horse's mouth and check the gums and teeth before fully committing to the horse.

    Sometimes a have to poke the horse a few times to wake it up before what I need.
    I talked to the horse's mouth today and sent the photo to that person, I hope to get their response within the next day or two.

    Our conversation went something to the effect of:
    - Yes, it is dangerous as there are a lot of unknown conditions, especially if we presume the first valve was leaking or otherwise not working and that is the reason for the installation of the second valve.
    - The first valve may not be working and therefore may not open.
    - If the first valve is working and does open, as soon as it opens and allows water to flow into the closed ended pipe, the pressure in the pipe will increase which will decrease the pressure across the first valve and allow the first valve to close. If the first valve closes before the second valve opens as is likely, the second valve will not open.

    That is when I suggested sending the photo to him so he could see what I was asking and see the actual installation.

    I will post the rely when I receive it - in the meantime, Jim can keep asserting that there is no danger while the rest of the world acknowledges that the installation is dangerous ... glad I am not a client of Jim's - he is either off the deep end with something being bad when it isn't ... or ... off the other deep end with something not being bad when it is. Sorry, Jim, but that is what your posts are like.

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  54. #54
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    Default Re: Double the protection!

    Quote Originally Posted by Jim Abram View Post
    Jerry - Sorry , I have never asserted that there is no danger.
    Jim,

    You have said that installation is not dangerous in many posts below, sometimes you stated it directly, sometimes indirectly, and sometimes by implying same.

    Quote Originally Posted by Jim Abram View Post
    Nice fake and entirely incorrect .
    Quote Originally Posted by Jim Abram View Post
    I do not think so.What do you hope to accomplish with the overstating of this condition.

    This is simply a non professional repair . Will it work correctly ? Maybe . Is it a hazard or bomb as claimed ,Unlikely.
    Quote Originally Posted by Jim Abram View Post
    Out of curiosity, I ran a test on this configuration this AM with two new valves . immediately . This is what I suspected would happen. The valve is just a spring loaded spindle. Pressure will open the spring and discharge the pressure.
    Quote Originally Posted by Jim Abram View Post
    I also do not see a brief release of 64 psi as very dangerous.
    Quote Originally Posted by Jim Abram View Post
    Those who claim it is dangerous or a hazard really need to do some research to justify that position.Isn't stating it is incorrect or a deficiency enough?


    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  55. #55
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    Default Re: Double the protection!

    Quote Originally Posted by Jim Abram View Post
    How do you get to hazard ?
    I know you said THE END, but Iím just answering your question, reminds me of physics class. If you stand on two scales and weigh 200lbs each will say 100lbs. If you stand on a scale on a scale, the top one will say 200lbs and the bottom scale will say 200lbs plus the weight of the first scale.

    From my understanding, simple example, in a perfect world, if you have two separately installed 30psi valves on the boiler and it hits 50psi both would open to release 10psi each. However, if they are in series the 1st one will open and when the pipe pressure hits 20psi the 1st valve will only notice a 30psi difference and close, and the 2nd valve feels 20psi. 30psi will equalize the pressure before and after the 1st valve, due to the 2nd valve, and another 30psi is needed to overcome the equalized pressure to open the 1st valve (30+30=60).

    Think of it this way, a car is in the ocean to the top of the doors and you try to open the door, you probably canít, too much pressure on the outside. Once the inside of the car fills up with water you will be able to open the door with no problems, equal pressure on both sides, little car big ocean. This is how that 1st valve is sitting in the line, like the car door, equal pressure on both sides. The 2nd valve feels the pressure, but the 1st valve is happy, feeling no pressure, as the pressure is equal on both sides, you need additional pressure on the 1st valve to open. Now, you might try to reverse this on me and say if the car is full of water it will pour out when I open the door, but what happens when I put the car in the ocean? Nothing, the water sits there until I add pressure to push it into the ocean.

    In a test, if you hook up two valves inline and turn on the garden hose each valve would open around 30psi (thatís what it does), but the water pressure being used is unknown. You need to know the PSI being used, not the PSI at the valves when they open, because that will always read around 30psi. If you run this test with a 40psi source I think you will find the 2nd valve will not open.

    But yeah, I think we all agree it should be changed, but this is one of my reasons why I think it is a hazard, plus the fact you have two devices that could fail vs. only one, like I mentioned in my first post.


  56. #56
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    Default Re: Double the protection!

    Let's say the both valves are in "showroom condition" (no build-up of anything on anything, no weakening of anything anywhere, and both open precisely at 30 psi ... okay, we both know that jus' ain't gonna be the case ... but suppose it was ... )

    The pressure reaches 30 psi and begins to release the water through the first valve and into the closed ended discharge pipe, as it does, the pressure in the closed ended discharge pipe begins to rise, as the pressure begins to rise on the back side of the valve that pressure (hydraulic and air pressure) are acting against the valve stem and valve trying to push it back onto its seat, that offsets - to some unknown degree - the pressure on the front side of the valve and the first valve closes; somewhere about now the second valve may begin to open, however, with the first valve closed, the pressure drops quickly and the second valve closes; the first valve begins to open again ...

    That cycle could conceivably oscillate back and forth creating an increasing water hammer effect which could cause one or both valve to fail or a pipe to fail.

    But, by Jim's assertion, that is not dangerous.

    The code and engineering requirements are such that no valves or caps should be on the outlet discharge side of a relief valve as that has been deemed not to be safe. By that understanding of not being safe, the installation of a second valve is considered unsafe ... I'm not sure what Jim thinks the difference between "unsafe" and "dangerous" is, but I am sure that Jim will have something which will prove (to him) that something which is "unsafe" is not therefore also "dangerous".

    ~~~~~~~~~~~~~~~~~~~

    Jerry:

    The yellow tags that are affixed to both of those valve say in part ďNo shutoff valve shall be installed between the relief valve and the boiler, or in the discharge line.Ē The 2nd valve can be considered such a valve. Also the possibility exists that if the valve connected directly to the boiler opens on pressure relief and the discharge is restricted (as it clearly is) the back pressure on the 1st valve may cause water to leak through the top or the bonnet of the valve where the lever pin comes through. This leakage would prevent the pressure from reaching the set point of the 2nd valve thatís actually providing the protection therefor leaving no overpressure protection for the boiler. Per ASME Sec. IV the safety relief valve should be installed in the vertical position.

    Regards


    Watts Regulator Technical Service
    815 Chestnut Street
    North Andover, MA 01845-6098
    Tel. (978) 689-6066 x 432155
    Fax (978) 689-6011

    ~~~~~~~~~~~~~~~~~
    I received the email below about an hour after the first email
    ~~~~~~~~~~~~~~~~~

    Jerry:

    Following is the response form the factory engineer for these valve. Itís pretty much a combination of your thoughts and mine.

    In parallel would be okay. But, in series is definitely not okay. The first valve will act as a flow restriction, trapped water in the valve outlet could bind it closed over time, pressurizing the valve outlet could cause it to close prematurely, etc, etc.


    Watts Regulator Technical Service
    815 Chestnut Street
    North Andover, MA 01845-6098
    Tel. (978) 689-6066 x 432155
    Fax (978) 689-6011

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  57. #57
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    Default Re: Double the protection!

    It's been a full day and not even one comment on what Watts said? Not even from Jim?

    Amazing.

    I believe that's a for this thread.

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

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