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  1. #1
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    Default Valve prohibited in hot water line at water heaters?

    Can anyone post the reference where there is a prohibition against having a valve in the hot water line at water heaters? Not talking about the TPR drain.
    Thanks

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    Jim Luttrall
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  2. #2
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    Default Re: Valve prohibited in hot water line at water heaters?

    Quote Originally Posted by Jim Luttrall View Post
    Can anyone post the reference where there is a prohibition against having a valve in the hot water line at water heaters? Not talking about the TPR drain.
    Thanks

    I just checked on that about a month ago. I did not see anything. I think it is a good idea to have one at the hot and cold for repairing fittings or changing the tank out.


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    Default Re: Valve prohibited in hot water line at water heaters?

    Don't know the exact reference but the tank could explode if the T&P Valve failed and the water shutoff valve were to be closed off on the hot side.

    rick


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    Default Re: Valve prohibited in hot water line at water heaters?

    This came up at a SOP changes class today and several seemed to be very certain as to the prohibition but, me being me, I need something in writing. I read though the IRC again and can't find anything not related to relief valves.

    Jim Luttrall
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  5. #5
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    Default Re: Valve prohibited in hot water line at water heaters?

    interesting... I always thought both valves were required.. 2006 Nat Sd plumbing code 10.16.2 note 2 ... A shutoff valve in the hot water supply is permitted.


  6. #6
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    Default Re: Valve prohibited in hot water line at water heaters?

    Quote Originally Posted by Jim Luttrall View Post
    This came up at a SOP changes class today and several seemed to be very certain as to the prohibition but, me being me, I need something in writing. I read though the IRC again and can't find anything not related to relief valves.
    I forgot all about that class. I was going to take it.


    I read thru everything when a client confronted me about it. Not that he confronted me but because I have seen it many times and thought nothing of it. You can have a shut off valve anywhere in the system. I just checked to keep from being asked in the future with still that slight, huh, in my mind.


  7. #7
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    Default Re: Valve prohibited in hot water line at water heaters?

    Quote Originally Posted by Ted Menelly View Post
    I think it is a good idea to have one at the hot and cold for repairing fittings or changing the tank out.
    That would only be needed if the water heater were in a basement and the hot supply lines went straight up.

    Quote Originally Posted by Rick Hurst View Post
    Don't know the exact reference but the tank could explode if the T&P Valve failed and the water shutoff valve were to be closed off on the hot side.
    Even with no valve on the hot supply side out of the water heater, it the T&P valve failed, there is going to be heck to pay, such as the water heater taking out a portion of the house when it explodes. The closed hot supply valve would just allow it to happen a little sooner is all (probably fraction of a minute difference at most, by reducing the amount of hot line it can push water into), all that super heated water pushes back out the cold inlet anyway.

    Jerry Peck, Construction / Litigation Consultant
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  8. #8
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    Default Re: Valve prohibited in hot water line at water heaters?

    Quote Originally Posted by Richard Pultar View Post
    first I looked in the new jersey edition of the IRC and there was no mention..
    What's a SOP class?

    It's the new standards or revised standards for Texas Inspectors. The class is on all the changes and you get 8 hours continuing ed for the class. Not big changes just some additions in what we have to report. Many of the items are written by inspectors anyway.


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    Default Re: Valve prohibited in hot water line at water heaters?

    The theory espoused by the people mentioning the prohibition of shutoff valves in the hot water discharge line (not the TPR drain line) was that opening a valve under a over heat condition would cause a rapid de-pressurization and flashing to steam with a resulting explosion. In theory, I suppose the science says that is possible but I am still looking for a code reference. I never see the valve, but I can see the need as water heating systems become more complex especially with multiple storage heaters. Heck, if I had two heaters in parallel, I would want isolating valves to add flexibility so that one heater could serve the house under light usage or emergency situations.

    Jim Luttrall
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  10. #10
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    Default Re: Valve prohibited in hot water line at water heaters?

    Jim:

    M2005.1 General.
    Water heaters shall be installed in accordance
    with the manufacturer’s installation instructions and the
    requirements of this code.Water heaters installed in an attic shall
    conform to the requirements of Section M1305.1.3. Gas-fired
    water heaters shall conform to the requirements in Chapter 24.
    Domestic electric water heaters shall conform to UL 174 or UL
    1453. Commercial electric water heaters shall conform to UL
    1453. Oiled-fired water heaters shall conform to UL 732.

    Aaron




  11. #11
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    Default Re: Valve prohibited in hot water line at water heaters?

    Thanks for the hint Aaron but I have looked at the IRC references you mention and have not found any mention of the prohibition of a valve.
    Could you be a little more specific?
    Thanks, Jim

    Jim Luttrall
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    Default Re: Valve prohibited in hot water line at water heaters?

    Here is a diagram from AO Smith showing valves in a two tank manifold system...

    Attached Files Attached Files
    Jim Luttrall
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  13. #13
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    Default Re: Valve prohibited in hot water line at water heaters?

    2006 Nat Sd plumbing code 10.16.2 note 2 ..." A shutoff valve in the hot water supply is permitted."


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    Default Re: Valve prohibited in hot water line at water heaters?

    Thanks Richard, that works for me!

    Jim Luttrall
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    Default Re: Valve prohibited in hot water line at water heaters?

    Quote Originally Posted by Jim Luttrall View Post
    Thanks Richard, that works for me!
    Except that the NSPC is not adopted in the State of Texas . . .


  16. #16
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    Default Re: Valve prohibited in hot water line at water heaters?

    Quote Originally Posted by Jim Luttrall View Post
    Here is a diagram from AO Smith showing valves in a two tank manifold system...
    That diagram shows that, on an AO Smith two-tank mainfold system, it is allowed. By that manufacturer and on that system.


  17. #17
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    Default Re: Valve prohibited in hot water line at water heaters?

    Which code is the current default TEXAS state code for plumbing?

    Last edited by Richard Pultar; 12-14-2008 at 10:51 AM. Reason: Texas

  18. #18
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    Default Re: Valve prohibited in hot water line at water heaters?

    Your right Aaron, but I still can't find any prohibition for a valve. Hard to prove a negative but seeing that is is allowed in at least some installations and is specifically allowed by some codes does lend credence to the theory that is is not prohibited.

    Jim Luttrall
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  19. #19
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    Default Re: Valve prohibited in hot water line at water heaters?

    Quote Originally Posted by Jim Luttrall View Post
    Your right Aaron, but I still can't find any prohibition for a valve. Hard to prove a negative but seeing that is is allowed in at least some installations and is specifically allowed by some codes does lend credence to the theory that is is not prohibited.
    You continue your search and so will I. Let's see if we can flesh out this theory.

    Aaron


  20. #20
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    Default Re: Valve prohibited in hot water line at water heaters?

    This is the best information I found on statewide codes, of course each municipality can adopt other codes or versions.
    Sec. 1301.255. ADOPTION OF PLUMBING CODES.
    (a) The board shall adopt the following plumbing codes, as those codes existed on May 31, 2001:
    (1) the Uniform Plumbing Code, as published by the International Association of Plumbing and Mechanical Officials; and
    (2) the International Plumbing Code, as published by the International Code Council.
    (b) The board by rule may adopt later editions of the plumbing codes listed in Subsection (a).


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  21. #21
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    Default Re: Valve prohibited in hot water line at water heaters?

    Quote Originally Posted by Jim Luttrall View Post
    This is the best information I found on statewide codes, of course each municipality can adopt other codes or versions.
    That's from the mopes at the TSBPE. The citation preceding that one is just as important:

    Sec. 1301.254. SEAL. The board shall have an official seal.

    Wonder what they feed him? Something from the Fish and Wildlife group?

    It does not apply in reality. Local option is the name of the game in Texas, but not when it comes to the IRC. It's mandated even in unincorporated areas. : Texas Administrative Code

    In any event there is no mention of the National Standard Plumbing Code, whatever that is. Dead horse is what it sounds like.

    Aaron


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    Default Re: Valve prohibited in hot water line at water heaters?

    I wonder what will go away if the TRCC is abolished in 2009 as recommended by the sunset commission?
    Of course you never know what will happen when the politicians get involved.

    Jim Luttrall
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  23. #23
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    Default Re: Valve prohibited in hot water line at water heaters?

    Quote Originally Posted by Jim Luttrall View Post
    I wonder what will go away if the TRCC is abolished in 2009 as recommended by the sunset commission?
    Of course you never know what will happen when the politicians get involved.
    Jim:

    Though I despise the TRCC and all that it represents, have fought it tooth and nail since its inception, and would love to see it burst into flames, I don't think it will happen soon.

    Bob Perry, the NAHB, TAB, the builders, et al. have invested too much of their dirty money in this cluster*%ck to allow the tax payers to nix it quite so easily. Though a return to RCLA would be better than the TRCC, I don't see that happening either.

    However, it may just be that the current problems with Detroit combined with the drop in new home starts will make this group of thugs a bit more amenable when it comes to doing things right. But I really doubt it.

    It will be interesting to see how this plays out.

    Aaron


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    Default Re: Valve prohibited in hot water line at water heaters?

    Quote Originally Posted by Jim Luttrall View Post
    The theory espoused by the people mentioning the prohibition of shutoff valves in the hot water discharge line (not the TPR drain line) was that opening a valve under a over heat condition would cause a rapid de-pressurization and flashing to steam with a resulting explosion.
    .

    Jim,

    There would not be "rapid de-pressurization" as the hot valve would open to a closed system, which already contains water, thus, being as water is a liquid, then hydraulics takes over and liquids do no compress, thus the decrease in pressure would only equal half the difference between the two pressures. Presume the hot valve was shut off at 70 psi, and the water in the tank is 140 psi (the T&P relief valve releases at 150 psi), then the water would, at most, drop to equalize the pressure to 105 psi, possibly not even drop that far as the pressure is expanding the water into the cold water line, and the pressure change in the hot water line would be gradual as the valve opens gradually (unless solenoid activated).

    Or maybe I am missing something??

    Jerry Peck, Construction / Litigation Consultant
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    Default Re: Valve prohibited in hot water line at water heaters?

    Can't debate the theory Jerry, it is not mine, I just repeated the theory put forth by some others. Do you have any information as to any prohibition of a valve in the discharge not relating to the TPR line in any code? Or the origins of the prohibition story?

    Jim Luttrall
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  26. #26
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    Default Re: Valve prohibited in hot water line at water heaters?

    The nat standard and the IBC replaced the uniform pl code with the last code adoption cycle in NJ
    published by the plumbing-heating-cooling contractors national association


  27. #27
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    Default Re: Valve prohibited in hot water line at water heaters?

    Jim,

    Never heard of a prohibition for putting a valve in the hot supply line.

    I do recall, I think, over the years having seen a few valves installed on the hot supply line - didn't set off any alarms in my head then, nor now.

    Jerry Peck, Construction / Litigation Consultant
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  28. #28
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    Default Re: Valve prohibited in hot water line at water heaters?

    I looked everywhere I could think to look and couldn't find much other than really tenuous and ethereal "evidence" to support this myth. So then, I guess that's just what it is - BS.

    After all, if one had a water heater that serviced only one branch with one sink, there would essentially be a shutoff valve in this line: the hot water valve in the sink faucet.

    Another one bites the dust . . .


  29. #29
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    Default Re: Valve prohibited in hot water line at water heaters?

    Not that it will matter much for enforcement in your areas but at least it may help to substantiate the idea.
    From the 07 Chicago plumbing code:
    18-29-503.1.1 Shut-off valves
    Shutoff valves for water heaters or heated water storage tanks may be installed on the inlet side only. This discharge side may be provided with a check valve or a 3-way valve installed to open the heater to the atmosphere when it is not in the operating position. The atmospheric opening of a 3-way valve shall be indirectly connected to the drainage system.

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  30. #30
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    Default Re: Valve prohibited in hot water line at water heaters?

    Quote Originally Posted by Markus Keller View Post
    Not that it will matter much for enforcement in your areas but at least it may help to substantiate the idea.
    From the 07 Chicago plumbing code:
    18-29-503.1.1 Shut-off valves
    Shutoff valves for water heaters or heated water storage tanks may be installed on the inlet side only. This discharge side may be provided with a check valve or a 3-way valve installed to open the heater to the atmosphere when it is not in the operating position. The atmospheric opening of a 3-way valve shall be indirectly connected to the drainage system.
    Marcus:

    Interesting. I'll check all of the local municipalites to see where they are with this.

    Thanks,

    Aaron


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    Default Re: Valve prohibited in hot water line at water heaters?

    Markus,

    "You da' man" when it comes to Chicago's codes!

    Did you pony up for a full copy of the Chicago ordinances?

    Michael Thomas
    Paragon Property Services Inc., Chicago IL
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  32. #32
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    Default Re: Valve prohibited in hot water line at water heaters?

    Quote Originally Posted by Markus Keller View Post
    Not that it will matter much for enforcement in your areas but at least it may help to substantiate the idea.
    From the 07 Chicago plumbing code:
    18-29-503.1.1 Shut-off valves
    Shutoff valves for water heaters or heated water storage tanks may be installed on the inlet side only. This discharge side may be provided with a check valve or a 3-way valve installed to open the heater to the atmosphere when it is not in the operating position. The atmospheric opening of a 3-way valve shall be indirectly connected to the drainage system.
    Interesting. IMHO it does not make any sense but it is interesting. You can have check valves or three way valves but not just a plain old shut off valve. All valves can go bad including check valves.


    A shut off valve does not affect anything to do with the safety of the hot water heater so I wonder why they chose to go with that code.

    Curious

    As Jerry stated/ It is a closed system if there is no fixture open and the WH still becomes a bomb if things go bad. Put a shut off valve in and nothing changes.


  33. #33
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    Default Re: Valve prohibited in hot water line at water heaters?

    Michael, yes to the books. I have to have them since I do work providing clients with info to defend themselves or with counsel against the City. The PL inspectors always write up valves on the hot side.
    Sorry Ted I don't know why the valve setup is written that way.

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    Default Re: Valve prohibited in hot water line at water heaters?

    Markus,

    Any chance I could get you to write up "The top 10 things those idiots home inspectors from the suburbs don't know about the Chicago codes"?

    Michael Thomas
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  35. #35
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    Default Re: Valve prohibited in hot water line at water heaters?

    When I plumb in tanks I put valves on both hot and cold makes it nice if they have to be replaced. City of Canton building inspector has seen them ,they never said a thing. When you stop and think about what makes difference you have a valve at every sink same thing


  36. #36
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    Default Re: Valve prohibited in hot water line at water heaters?

    Michael, that might be a little difficult. I don't think I've really thought about it in those terms. When clients hire me to do a follow-up insp after they've already paid for an insp by someone else, there is usually a different set of issues I run into. I don't generally go over suburban reports being done in the City. (I don't recall one specifically now). My issues tend to involve franchise/checkbox inspections done by others. My potential clients either realize what they've paid for is a piece of crap or ask for 'translation' services, then find out it's a piece of crap. Some of the 'prettier' reports contain some much trade jargon/fluff that a lay person doesn't know what the hell it all means. Therefore it gets them no closer to understanding their potential new home.
    I also have the IRC and other code books. I find that clearly there is a lot of difference in finding items in each but the fundamentals are generally similar. Some of the City codes are a bit antiquated and bizarre at times. Understanding what to do with a particular code section and how it applies to a construction and occupancy class is more important for me.
    I'll give you thought some thought.
    Markus

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  37. #37
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    Default Re: Valve prohibited in hot water line at water heaters?

    In Illinois, it is not prohibited.


  38. #38
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    Default Re: Valve prohibited in hot water line at water heaters?

    Quote Originally Posted by Jerry Peck
    There would not be "rapid de-pressurization" as the hot valve would open to a closed system, which already contains water, thus, being as water is a liquid, then hydraulics takes over and liquids do no compress, thus the decrease in pressure would only equal half the difference between the two pressures. Presume the hot valve was shut off at 70 psi, and the water in the tank is 140 psi (the T&P relief valve releases at 150 psi), then the water would, at most, drop to equalize the pressure to 105 psi, possibly not even drop that far as the pressure is expanding the water into the cold water line, and the pressure change in the hot water line would be gradual as the valve opens gradually (unless solenoid activated).

    Or maybe I am missing something??
    An interesting thought, but if the pipe on the down stream side of the valve was drained for maintenance etc. or if the hot water faucets were left open when the valve was closed depressurization could occur.

    Not sure about that. Half the diffences in pressure could only occur if the volume of water in the tank was equal to the volume of water in the pipe on the downstream side of the valve. (closed system conditions only)


  39. #39
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    Default Re: Valve prohibited in hot water line at water heaters?

    Quote Originally Posted by Ken Amelin View Post
    Not sure about that. Half the diffences in pressure could only occur if the volume of water in the tank was equal to the volume of water in the pipe on the downstream side of the valve. (closed system conditions only)
    Correct, but that was not within the context of the question, so I did not want to start bringing in more information which may confuse the matter.

    Take Aaron's example of one water heater supplying one sink with one hot water line, which makes since if that is in a garage or basement and someone adds a water heater for that sink. In that case, there would be relatively little water volume in the hot piping as compared to that in the water heater that the pressure drop would be minimal, if even noticeable.

    Take the other extreme (and which is probably typical on a larger house) and the hot water pipes might contain, at most, 25% of the volume of water which is in the water heater, the pressure would drop, but not significantly.

    I was proposing a volume for volume *worst case* scenario to reach a half pressure drop. In real life, having 85 gallons of hot water in the lines for an 85 gallon water heater would likely never occur - that is *a lot* of hot water lines.

    Jerry Peck, Construction / Litigation Consultant
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  40. #40
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    Default Re: Valve prohibited in hot water line at water heaters?

    From the "safety" point of view there is no sense to install them on the hot side....
    From the installer point of view either....
    In my modest recently experience replacing a few dozen water heaters about 25 years old in a complex apartment building NONE of the shut off gate valves installed originally only on the cold side worked with no leaking, having to divert the leak with a hose to the next sink, having to shut off the main cold, purging the system opening every faucet and having to replace the valves too .....


  41. #41
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    Default Re: Valve prohibited in hot water line at water heaters?

    Nothing prohibits you from installing a shutoff on the hot side. A closed valve on the hot side is no different than all of the fixtures on the off position anyway. No big deal.

    If you don't like it in your own home then don't do it. If you are an inspector, then there is nothing you can do about it. If you are a HI and call it out then you do not have a leg to stand on.


  42. #42
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    Default Re: Valve prohibited in hot water line at water heaters?

    Quote Originally Posted by Jeff Remas View Post
    Nothing prohibits you from installing a shutoff on the hot side.
    Unless you are in Chicago.

    Quote Originally Posted by Markus Keller View Post
    From the 07 Chicago plumbing code:
    18-29-503.1.1 Shut-off valves
    Shutoff valves for water heaters or heated water storage tanks may be installed on the inlet side only.


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  43. #43
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    Default Re: Valve prohibited in hot water line at water heaters?

    I have heard that there are a few local ordinances that prohibit it too.


  44. #44
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    Default Re: Valve prohibited in hot water line at water heaters?

    Quote Originally Posted by Jerry Peck View Post
    Unless you are in Chicago.
    Again, and not to be picky mind you, if you have a water heater with only one hot water fixture attached to it - let's say a sink faucet valve - then that constitues a shutoff valve. Does it not? Even if it does not, then the required shutoff valve supplying the faucet does. Is that valve then illegal?


  45. #45
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    Default Re: Valve prohibited in hot water line at water heaters?

    I know at least part of the idea behind no shut-off on the hot side is that if pressure builds up in the tank, then a closed valve won't contain the pressure and the tank won't blow through the roof.
    This is strictly speculation on my part ...
    With no shut-off valve on the hot side but shut-offs at faucets, my guess is that there may be an assumption that the supply lines at the faucets or piping along the run will blow first to relieve pressure rather than the tank blowing through the roof. Thereby minimizing life threatening damage.

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  46. #46
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    Default Re: Valve prohibited in hot water line at water heaters?

    Quote Originally Posted by Markus Keller View Post
    I know at least part of the idea behind no shut-off on the hot side is that if pressure builds up in the tank, then a closed valve won't contain the pressure and the tank won't blow through the roof.
    This is strictly speculation on my part ...
    With no shut-off valve on the hot side but shut-offs at faucets, my guess is that there may be an assumption that the supply lines at the faucets or piping along the run will blow first to relieve pressure rather than the tank blowing through the roof. Thereby minimizing life threatening damage.
    Marcus: Aren't the thermostat and TPR in place to serve that function? And what should lead one to believe that a shutoff valve placed inline and adjacent to the tank would be more integrous than a shutoff valve placed anywhere else in the hot water line?


  47. #47
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    Default Re: Valve prohibited in hot water line at water heaters?

    I'm not sure I'd rely on the tpr or stat, even though it's there for safety.
    I have seen tpr's capped off at the floor 'because it drips', plugged with rust or not even installed.
    I have seen many a HWT with the big red temp knob missing. Knowing what temp it is set at is sometimes a guess.
    As far as the valve at the tank or a shut-off down stream at a faucet, I think a 3/4" or 1" brass ballcock would handle more pressure than a crappy plastic/ china metal shut-off or plastic supply line.

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    773/844-4AIC
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  48. #48
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    Default Re: Valve prohibited in hot water line at water heaters?

    Quote Originally Posted by Markus Keller View Post
    I know at least part of the idea behind no shut-off on the hot side is that if pressure builds up in the tank, then a closed valve won't contain the pressure and the tank won't blow through the roof.
    This is strictly speculation on my part ...
    With no shut-off valve on the hot side but shut-offs at faucets, my guess is that there may be an assumption that the supply lines at the faucets or piping along the run will blow first to relieve pressure rather than the tank blowing through the roof. Thereby minimizing life threatening damage.
    History has shown that not to be the case, otherwise you would never have water heaters exploding and damaging buildings and injuring people, which happens 30-40 each year across this country of ours.

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

  49. #49
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    Default Re: Valve prohibited in hot water line at water heaters?

    Has the final verdict came in as of yet?

    From today.

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  50. #50
    A.D. Miller's Avatar
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    Default Re: Valve prohibited in hot water line at water heaters?

    Quote Originally Posted by Rick Hurst View Post
    Has the final verdict came in as of yet?

    From today.
    Rick:

    I think, and please forgive me if I am presumptuous or write precipitously, the verdict is that there is no ICC prohibition concerning the placement of a shutoff valve in the hot water line that exits a water heater.

    The caveat being, as usual, that your AHJ may in some shape, form or fashion be inhaling the same Herbes de Brilliance as ECJ, as in the case of Chicago. There, quite literally, things are done differently. If you have an open senate seat you sell it. If you have an open water line you seal it.

    Aaron


  51. #51
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    Default Re: Valve prohibited in hot water line at water heaters?

    rick,
    i have never written it up as a code violation and that is one butt ugly soldering job


  52. #52
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    Default Re: Valve prohibited in hot water line at water heaters?

    Boy James, you have been digging deep to revive this old thread!
    No prohibition nor requirement for a service valve at the hot line at the tank. Who cares if it leaks when someone is stupid enough to operate the valves with no heater in place? There is no way to fix stupid and no way to write codes to anticipate all the possible stupid acts.

    Jim Luttrall
    www.MrInspector.net
    Plano, Texas

  53. #53
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    Snowbird (this means I'm retired and migrate between locations), FL/MI
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    Default Re: Valve prohibited in hot water line at water heaters?

    MT, The Illinois Plumbing Code also expressly prohibits said valve on the hot side of a water heating storage vessle, and now requires a full bore open valve on the inlet side.

    It comes from the UPC based codes and experience with hydrogen gas - a natural result from the heating/reheating of unused water in the closed tank. Friction or other restriction when that first at use valve opens after a long period of non-use can be explosive. There are warnings on the tanks themselves that warn of long periods of non-use of water with the water heater left to fire to maintain a higher desired at use temperature - and why we are advised to turn down the thermostat to a "vacation" temperature or pilot only if away for long periods of time.

    More and more homes have closed systems/required check valves, vacuum breakers, expansion tanks, etc. regarding pressure build up/lack thereof.

    The addition of an outlet side valve doesn't offer much in the ease of a swap-out/replacement, one need only open the point of use valves and allow the pipes to drain; one still needs to re-sanitize the system after the repair - running chlorinated "city" water through continuously for a time certain to "flush" and sanitize, or using sitting bleach & water solution or hydrogen peroxide to hold in the system for a time certain and flush in the case of non-chlorinated water supplies.


  54. #54
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    Jul 2009
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    Lanham, MD
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    Default Re: Valve prohibited in hot water line at water heaters?

    Not a problem as far as heating and expansion goes as long as both valves (if equipped) are not closed, in which case the TPR would open to relieve the pressure. Regardless, if the cold side valve is open, any expansion would simply push back into the water service (assuming the water service is not equipped with a pressure reducing valve or check valve).


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