Shutoff Valve in Hot Water Line of Water Heater

[aaronm]

Is there any model code, manufacturer's installation instruction, or just plain reason that prohibits the installation of a shutoff valve in the hot water line coming out of the top of a water heater?

[Verdeboy]

Not that I know of. Many HW tanks have shutoffs at both the inlet and outlet.

[Gary Swart]

You should put a valve on the hot water line so that you can flush the tank without washing crud into it. One on the cold intake side isn't so useful, but with one, you could remove the tank without turning off the entire house water, and it's cheap enough to do. I use full flow ball valves.

[hj]

Some, not "many", water heaters have valves on both side. I run across ONE every ten years or so. And the one on the cold side is REQUIRED by all codes, even though someone says it is "not useful".

[Verdeboy]

Most of my previous experience is with larger tanks used in apartment buildings. They almost always have two shutoffs.

Recently, however, most of the residences I have worked in have zero shut-offs, which means no water until their tank is replaced (or until I install the CW shutoff).

[Ian Gills]

Are all of you completely mad? Or is it 1 April?

Even a DIYer knows this one, which says something.

It is incredibly dangerous and absolutely against code to have a shut-off on both the inlet and outlet of a hot water heater. If both are closed, the WH relies completely on the proper functioning of the PRV to deal with pressure/expansion changes and faults if the heater is left on.

If the PRV fails, then we start to see explosions of the type some of you post links to on this site every now and again.

My neighbor has valves on both the inlet and outlet of his WH and I live in fear. Say he shuts them both off and forgets and the PRV fails?

Shut-offs on WHs should only be installed on the cold side. That way, the fixtures and fittings (think washer hoses) of the hot supply will also take the strain of any increase in pressure should the PRV fail and there is fault with the WH. There is therefore less chance of a boom.

How many bombs are you guys making?

LONG LIVE D.I.Y.

[Gary Swart]

Regarding my statement that the valve one the "cold side wasn't as important etc.. My bad!!:o I certainly meant the valve on the HOT side was not as important as on the intake (cold) side. Thanks to HJ for catching my error!

[Ian Gills]

I cannot believe we are still sitting here entertaining this very idea.

Am I dreaming?

Or have I died and been reincarnated into a new world where there is a different plumbing code as well as a new law of physics?

Or both?

Two shut-offs on the outlet and inlet of a WH equals a potential boom. Period. Don't do it. Shut-offs, like expansion tanks, should only be installed on the cold side.

[Verdeboy]

Take it easy, man. You are the one about to explode.
The only reason anyone would shut off those valves is to do maintenance or to replace the tank.

And, even if both valves are closed while the tank is fired up, in order for it to become a bomb, both the thermostat and the T&P valve would have to fail.

[Ian Gills]

I am cool.

Just trying to invoke some passion and debate.

I get as good as I give on here anyway.

[kingsotall]

aaronm, is there any particular reason you were asking or were you just wondering¿

[Probedude]

I am cool.

Just trying to invoke some passion and debate.

I get as good as I give on here anyway.

Think of it this way in regards to the water heater being a bomb if the inlet and outlet were shut off and the TPV failed
- how is this different than if the inlet were shutoff and no other hot water fixture in the house was turned on? It's still a closed system.

[Ian Gills]

You have washer hoses, copper fittings and all sorts of other fixtures that will probably fail before the water tank does.

Not to mention you might notice the problem in the chance you open a tap.

[Ladiesman271]

I have a shutoff valve on the cold side as well as the hot side of my water heater. The T&P valve is between the hot water output of the water heater and the hot water shutoff valve.


Works fine!

[Ian Gills]

Again, I raise an objection.

If a licensed plumber installed a shut-off on the hot side of my tank I would be extremely disappointed, and tell him to remove it.

Of course he wouldn't because they all want to save a few bucks on fittings.

But more importantly it is against code.

I am more than slightly surprised that a few of the pros around here are not jumping in and backing me up on what is a basic safety issue.

[Ian Gills]

I have checked and it would not appear to be against code everywhere, as I originally assumed. Sorry. In Illinois for example it appears to be allowed.

But I maintain that it is dumb to have two shut-offs on a WH. If you the plumber have put a ball valve on the hot you have opened the door for human nature to injure someone.

They possibly would not want to call a plumber when the T+P is working properly and releasing water.
They put a cap on the T+P "I can fix this honey"...
The heater builds up excessive pressure and pinholes a weld on the tank...
They close both valves and know it is now time to call you to replace the heater...
You pull up to a house with a bunch of emergency vehicles in front of it because the homeowner never turned off the gas,"It wasn't what was leaking"
With hot open maybe they will have a chance blowing a water supply.

Yes, there might be exceptions. From my 365+ days of plumbing experience as a fully qualified and master homeowner, I would guess that on a residential 2 heater parallel installation, installing a hot and cold on each heater might be essential. When 1 heater takes a dump, that heater can be isolated, and the other heater will work without the leaker leaking.

But I maintain that traditionally a 1 tank residential heater will only have a cold water valve.

A tankless might require both a cold and hot shut off with bypass valves to allow for flushing though.

[jar546]

Ian,

It is not against code to add a shut off on the hot water side and it makes it easier to service the equipment. The TPR valve is what protects the equipment. If you don't have one and all of the hot water fixtures are in the off position, it is no different than having a valve installed on the hot side and in the closed position.

I understand your concern and appreciate your passion but you are incorrect.

I think you need to specify the code that prohibits this, otherwise you are misleading people with false information.

A shutoff valve is required on the cold water side per the IPC and IRC. In the IPC it can be found in 503.1 and in the IRC it is in P2903.9.2

I have supplied you with direct references, now I ask the same from you.

[jar546]

Also,

You cannot fix stupid and keep people from injuring themselves due to their own negligence. It is bad enough that we have to have stickers on lawn mowers telling people that they are not hedge trimmers because some moron picked up a mower to trim his hedges and won a lawsuit.

Under normal operating conditions, the valves will be in the open position.

Again, as long as you don't have water running in the house, there is no difference between that and a closed valve on the hot side. Either way the water is restricted and pressure can build up, hence the need for a TPR valve.

If you are stupid enough to cap the TPR, leave the gas on and turn off both valves then you don't belong in society anyway.

If you don't like it then don't do it in your house. It is not required but it certainly is not against any nationally recognized codes.

[Ian Gills]

Many thanks for the clarification.

I must have been confused on this one.

I guess I am just be one of those weirdos who likes to see installations done as per the manufacturer's installation instructions, which never show a hot-side shut off valve for a traditional single tank installation.

[GabeS]

I'm with jar on this one. I don't see how a closed faucet or shower head is any different from a closed valve. I guess Ian is suggesting that a soldered copper elbow is a weaker connection than a valve and would burst before the tank would as opposed to a ball valve not bursting in a high pressure situation. This may or may not be correct, but I can't imagine a huge difference in strenght between the two.

Also, I believe a bigger concern would be to have threads on the bottom a T&P extension pipe, where a unfamiliar homeowner would even have the ability to cap it. Absolutely no threads allowed on the bottom of that pipe.

A hot water side valve would allow you to change the water heater without having to drain all the hot water lines.

[burleymike]

Come on now, you don't have to worry about excess pressure if you have brass Zurn pex fittings!:D

[Basement_Lurker]

Many thanks for the clarification.

I must have been confused on this one.

I guess I am just be one of those weirdos who likes to see installations done as per the manufacturer's installation instructions, which never show a hot-side shut off valve for a traditional single tank installation.



You are correct to follow the manufacturer's installation guides, however, just like the installation requirements in a code book, they are just minimum guidelines on how to do it. While I don't agree with you that having a shutoff valve on the hot water line is a safety issue, I will say that for a normal sized home, having a hot water shutoff isn't really necessary since it doesn't take much longer to drain down the hot water lines while you are draining down the tank.

However, I will say that I always install a valve on the outlet and inlet side of the tank. But that is just because of the way I plumb in a tank with flex hoses; it just makes it so much quicker and simpler for the next guy who replaces the tank.

[hj]

There is no prohibition against a valve on the hot water side, in fact mechanical engineers usually specify one on the larger projects. In a parallel multiple heater setup they would be required in order to isolate individual tanks when they fail. In other situations they can be a convenience. But in systems with basic flaws, they will mask the problem.

[SewerRatz]

I swore it was in the Illinois plumbing code, but I do know many local codes which can be stricter than the Illinois code does not allow a shut off on the hot discharge side of the heater.

As for there is no difference than having a shut off valve on the hot side or a faucet making it a closed system, there is a HUGE difference. I was called by a car dealer that told me they had smoke coming out of their water closets. When I got their it was steam coming out of the W/C sinks and wall hydrants for the car wash. I walked up to their water heater it was running non-stop, the hydro-stat failed, and the P&T valve was frozen shut. I shut the heater down opened a yard hydrant till cold water ran. Replaced the hydra-stat and P&T valve, as well as rebuild all the Sloan valves, faucets and any other valve that used a rubber to make a seal. If for some reason they had a ball valve on the outlet and it was closed that tank (120) would of launched it self and taking out half the dealership. But they got lucky the water was so hot it back flowed through the cold water and meted the rubber seals.

So I say NEVER NEVER NEVER put a shut off valve on the hot side of a tank. So damn what you need to drain down the hot side. Big whoop.

[theplumber]

If your local codes allow it, I'd put one on both sides just so you don't have to drain it down. The real benefit of having the shut off on the supply side is mostly for that 8pm bottom of the water heater blows out on you moment. That way you can flush the toilet as much as you like until you get the new heater in. Also if you don't ahve one on the supply side and you just have a gate valve for your main, it will not shut off the water completely. Depending on where the WH is, it could mean the difference of a ruined wood floor or just a wet smitty pan that causes no problem.

[jar546]

I believe Chicago does prohibit the valve on the hot side.

[Verdeboy]

I swore it was in the Illinois plumbing code, but I do know many local codes which can be stricter than the Illinois code does not allow a shut off on the hot discharge side of the heater.

As for there is no difference than having a shut off valve on the hot side or a faucet making it a closed system, there is a HUGE difference. I was called by a car dealer that told me they had smoke coming out of their water closets. When I got their it was steam coming out of the W/C sinks and wall hydrants for the car wash. I walked up to their water heater it was running non-stop, the hydro-stat failed, and the P&T valve was frozen shut. I shut the heater down opened a yard hydrant till cold water ran. Replaced the hydra-stat and P&T valve, as well as rebuild all the Sloan valves, faucets and any other valve that used a rubber to make a seal. If for some reason they had a ball valve on the outlet and it was closed that tank (120) would of launched it self and taking out half the dealership. But they got lucky the water was so hot it back flowed through the cold water and meted the rubber seals.

So I say NEVER NEVER NEVER put a shut off valve on the hot side of a tank. So damn what you need to drain down the hot side. Big whoop.

That tank was already a bomb. You just arrived in time to deactivate it. If someone was stupid enough to close the valves, it may have blown up before you got there, but as someone said, "you can't fix stupid." A better idea would be to create and enforce a preventive maintenance schedule to test the T&P valve, etc..

[SewerRatz]

I believe Chicago does prohibit the valve on the hot side.
I think so too, but its to dang cold out for me to run out to my truck and dig up the Chicago code book. I wish they post the Chicago code online, would make life so simple, but then they can not charge you $125 bucks every other year to get the new code book.

Verdeboy: Well if they turned off the cold valve, the presure would of melted the rubbers in the hot side of the faucets.. actuly it did, as I think a bit more what I had to do to repair the stuff. But in this case the P&T Valve was only a year old, and the thermostat died in the on postion.

I had a lady e-mail these pics and told me she heard a loud bang and a pop come from her water heater. I told her to get out of the house now and call the gas company to turn off the gas to the home. I showed up an hour later as the gas company guy was just leaving.

http://i7.photobucket.com/albums/y292/SewerRatz/Water%20Heater/IMG_1958.jpg http://i7.photobucket.com/albums/y292/SewerRatz/Water%20Heater/IMG_1959.jpg http://i7.photobucket.com/albums/y292/SewerRatz/Water%20Heater/IMG_1957.jpg

[frenchie]

Never mind that, he's not even making sense.

He says what saved it was that the hot water backflowed on the cold side. Steam coming out of the toilets...

How would a valve on the hot side have prevented that, or affected the situation in any way whatsoever?

[SewerRatz]

Never mind that, he's not even making sense.

He says what saved it was that the hot water backflowed on the cold side. Steam coming out of the toilets...

How would a valve on the hot side have prevented that, or affected the situation in any way whatsoever?

Well in this case the cold water got used more than the hot, with the increased pressure in the tank it backflowed towards the water closets and the other faucets that where used. Now I also posted that I did have to replace rubber washers that melted away in some faucets as well. If some one turned off the cold water supply the water still would of melted the rubber seals in the hot taps. Now if there was a shut off valve (which are normally ball or gate vales) on the hot side as well as the cold site and they both where off, this tank would of blown up. I am sorry I did not mention that I did have to replace washers on the hot taps as well. The fact of seeing steam out of a water closet was pretty amazing and the detail of replacing rubber seals on both hot and cold fixtures slipped my mind.

[Probedude]

As for there is no difference than having a shut off valve on the hot side or a faucet making it a closed system, there is a HUGE difference.

Worked out great for that particular instance, but I'm sure we could all draw on paper a situation where it wouldn't have helped.


If some one turned off the cold water supply the water still would of melted the rubber seals in the hot taps.
Only if there were flow. With no flow, the heat would have been dissipated long before reaching those close faucets so they would never see the scalding temp.
Though I doubt they could melt anyways at boiling water temps since that's as high as it would have been.

[Dunbar Plumbing]

Is there any model code, manufacturer's installation instruction, or just plain reason that prohibits the installation of a shutoff valve in the hot water line coming out of the top of a water heater?


One of the most dangerous situations you create.


Two valves off, water heater kicks on and the T&P is clogged...


A pressure cooker that when it explodes, will kill and destroy your property.

Having the ENTIRE plumbing system to use as a buildup for when a supply line blows or forces a fill valve to malfunction, anything is better than containing that water heater expecting that $7 relief valve to open up when you need it most.


I've removed every hot side shutoff on every water heater I've replaced, no exceptions and I've warned every customer of the ones I've beared witness to.

Things can and will go wrong in plumbing and just because you know how your plumbing system operates, doesn't mean your wife, kids or the incoming new property owners know what kind of bomb you built in the basement.

[frenchie]

Ratz, what you're basically saying , then, is:

if there was a shutoff on the hot side, and if they shut it off, and also closed the (existing) supply-side shutoff...that would be really be dangerous... if or when something went wrong with the t&p valve.


Whereas if there isn't a shutoff on the hot side, they could only shut off the cold, and so if or when something goes wrong with the t&p, at least the seals on the faucets (hot or cold) can blow & let off some of the excess pressure?


I have to ask you why the hell anyone would turn off the inlet OR the outlet to a tank? What possible scenario you can see where someone would do that, unless they were swapping it out?

[Dunbar Plumbing]

I have to ask you why the hell anyone would turn off the inlet OR the outlet to a tank? What possible scenario you can see where someone would do that, unless they were swapping it out?




Because people are effing retarded most times when they have a leak in their home, and they start that chain reaction of shutting valves off until the leaks stop, not understanding that there's a water heater sitting there operating because they think the device shuts down when the water is turned off.


That's simply not true.

Ian Gills is spot on with his thinking and this is where any mode of thinking that implies you got any sense about you does NOT need to be a reference back to any code, provision, statute or law.

It's called "logical thinking" and you either have it or don't.


Code in KY doesn't restrict that hot side valve, but that doesn't mean that I as a plumber don't understand that two valves off and a thermostat kicking on to either satisfy a temp drop or the leak that removed the ready to use hot, put you in sync with relying on a T&P that I've seen clogged completely shut in less than two years.


Did you all even realize that the mfg. of all water heaters require annual tripping of that valve, replacement after a couple years? That would be ideal but half the fools that install them, never install the drip leg down to the floor because they're too inept to understand any different.


I'm a code abiding plumber but I don't support weak arguments because they don't exist in print, in code. It's the probability standard along with years of experience knowing the what ifs in plumbing and how detrimental an okay or nod, an acceptance that since it isn't in the book that it's a go.

Total bullshit and you'll be held responsible for your bad advice if someone is killed for what we all know is a bad situation when thermal expansion becomes a multiplier for pressure and no weak links in the chain to break before the big one lets go.


Kudos to Ian, don't cowl down when you know you're right. That's something you'll never see from me in person or in print.

[frenchie]

Because people are effing retarded most times when they have a leak in their home, and they start that chain reaction of shutting valves off until the leaks stop, not understanding that there's a water heater sitting there operating because they think the device shuts down when the water is turned off.

You had me at "retarded". :D

[GabeS]

Why don't they install high temperature shutoffs on hot water tanks like they do on boilers? Or expansion tanks on hot water tanks? They are closed systems, right?

Now I know to remove any valves on hot water side of hot water tank. I think that point has been made rather clear. I don't see any clear arguments why it should stay there.

The point about the water only reaching boiling water. In a closed system the water can heat up to a much higher temperature before it boils because it is under pressure.

Everyone keeps saying why would someone close both valves. I think it's obvious that the chances are very very low. But it only takes one exploision to kill someone.

[Dunbar Plumbing]

Why don't they install high temperature shutoffs on hot water tanks like they do on boilers? Or expansion tanks on hot water tanks? They are closed systems, right?

Now I know to remove any valves on hot water side of hot water tank. I think that point has been made rather clear. I don't see any clear arguments why it should stay there.

The point about the water only reaching boiling water. In a closed system the water can heat up to a much higher temperature before it boils because it is under pressure.

Everyone keeps saying why would someone close both valves. I think it's obvious that the chances are very very low. But it only takes one exploision to kill someone.


That would be ideal if there was high temperature shutoffs, but considering anything mechanical can and will fail, that's another device in the series of many that can protect only if it is working.


On expansion tanks, Code in KY states that the tee for the line for the expansion tank must be between the cold water shutoff and the top of the water heater. That way in the scenario if the cold water valve is shut off, the expansion tank is NOT isolated from the heater that is producing thermal expansion.


If a water heater produces a full tank of ready to use hot water, I can cut the lines off that tank at the top and water will "well" out of that tank for hours. That's why you can put your hand on the cold water inlet if no water has been used in the house for some time and the cold water inlet line will be warm/hot due to thermal expansion.


We shouldn't expect property owners to understand the particulars of plumbing. They just know it's broke when it doesn't work. That's why plumbers that are educated like us need to stand up to the plate and educate the masses of worst case scenarios because they do indeed happen. Was this the site that had the guy who ran new copper to the water heater and the top collapsed in because of a backflow device?

Could of been an even greater disaster and I believe the guy was so embarrassed after we did a pile-on that he didn't want to face the music how right we were, how deadly wrong his actions were. He had a family in that home as well.


So those of you dismissing these hazards, you're not speaking from the extensive knowledge a plumber posesses. I'm sure I can question the rhetoric of the rules you play by but somewhere in the mix you have to put case history into thinking.


Dual valves on commercial applications, large condo units, you know why?

Far less chance of "uneducated" hands ending up on those valves, even though bad things like hot reversal causing burns have happened in this mode when 1 of 3 units are down and a crossover occurs.

You're not going to have Miss Daisy trying her luck at stopping the leak in that scenario. In her home, yes, a large building....maintenance or plumber is coming.


Closed systems like a PRV on the main line, a common device nowadays. Dual Check Valve assembly = water comes in, never goes back out.

People misunderstand/underestimate plumbing and its hazards.

[Dunbar Plumbing]

You had me at "retarded". :D



LOL! I like the picture. I'll have to pay you royalties every time I use it.

[Probedude]

Why don't they install high temperature shutoffs on hot water tanks like they do on boilers?

They don't? My previous 3 have them.

[SewerRatz]

Ratz, what you're basically saying , then, is:

if there was a shutoff on the hot side, and if they shut it off, and also closed the (existing) supply-side shutoff...that would be really be dangerous... if or when something went wrong with the t&p valve.


Whereas if there isn't a shutoff on the hot side, they could only shut off the cold, and so if or when something goes wrong with the t&p, at least the seals on the faucets (hot or cold) can blow & let off some of the excess pressure?


I have to ask you why the hell anyone would turn off the inlet OR the outlet to a tank? What possible scenario you can see where someone would do that, unless they were swapping it out?


People do it all the time. Lets say they where changing a Moen cartridge on a shower valve that does not have stops. They turn of the water at the meter and turn of the valves at the water heater. There can be a ton of what ifs.



Probedude: Here is the trouble. If water that is in a pressure vessel, boiling point is a whole lot higher than normal. The more pressure on the system the higher the boiling point is. They call this water super heated. When this super heated water is exposed to normal atmosphere it flashes to steam. Which can and in the case I pointed out did melt the rubbers on the faucets, and the Sloan flush valves. Now will this happen in every case. NO , in other cases like the picture of the water heater I posted the water was on and the water did get super heated and caused the tank to buldge.

In the car dealership where the rubbers did get melted everyone was lucky that (a) that the heater did not blow up (b) no one got hurt by the steam coming out of the fixtures. You know anyone that doesn't believe that a water heater that has a failed Pressure and Temperature valve and the thermostat does not shut down the heater is a danger you should go to Watts web site and order the free video Explosion - Danger Lurks. Also you should ask for the Danger - Scalding Lurks and heck just for grins Water Backflow Prevention.

Here is the link to the order form http://www.watts.com/pro/divisions/watersafety_flowcontrol/learnabout/learnabout_dvdorderform.asp

[Probedude]

Here is the trouble. If water that is in a pressure vessel, boiling point is a whole lot higher than normal. The more pressure on the system the higher the boiling point is. They call this water super heated. When this super heated water is exposed to normal atmosphere it flashes to steam. Which can and in the case I pointed out did melt the rubbers on the faucets, and the Sloan flush valves.

You're right about the rise in boiling point - I completely overlooked that.

Still though there are 3 safety mechanisms that have to fail

- high temp cutoff not working
- thermostat not working
- TPV not working

So all these failed in your example apparently. I can see the point of not having a shutoff on the output of the WH, but if all three safety mechanisms fail I would say that this would be a big problem in MOST installations regardless.

[SewerRatz]

Ahh found my Chicago code book. Dang brother-inlaw had it.

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.

[Homeowneress]

Ian Gills, "Robin Hood", thank God you posted on here in rebuttal and got the debate going and then cleared up....thanks to SewerRatz expertise and further input.

I noticed water on my garage floor and traced it back to a drip leak at a section right near the hot water shut off valve. My husband and I were leaving for a cruise that early morning and had no time to call the plumber. Touching the drip it was hot water, and I concluded it would stop if I shut off the hot water valve, which it did. I then went outside and turned off the main and we left for a 10 day cruise. I had no idea this was a potential killer bomb. Now I know. Hope others will chance upon this thread and learn the danger involved in the simple act of shutting off a shut off valve. Wow, I get sicked thinking about what I could have caused. The gas company should really send out stickers to be placed next to any water heater hot water shut-off valve to each and every home, that says "do not shut off this hot water shut-off valve for more than 30 minutes - explosion danger!!".

Thank you Ian Gillis, "Robin Hood", and SewerRatz!!!!!!!! Your posts may save lives.

[ballvalve]

Like I have been saying for years, you need REDUNDENCY- back up to the single stupid relief valve.

And guess what boys, its made, and no one uses it because granpa didnt have one.

http://media.wattswater.com/es-BRV.pdf

http://www.watts.com/pages/_products_details.asp?pid=564

Anyone ever heard of a tee with a secondary, plain pressure relief valve on the heater also? Is 12 bucks too much to save a house or heater? Got a car without an emergency brake lately?

It was too expensive for for the Japanese at their sieve of a nuclear plant, and now have a look at what their lack of forethought caused. -30 kilometer circle of new wilderness, and fish that glow in the dark.

Funny how they floated their department stores on huge springs. Built the reactors rock solid. I guess the Prada purses are more important that a few hundred thousand houses being abandoned.

[Redwood]

Oh Boy...

Here we go again...

http://www.watts.com/pages/_products_details.asp?pid=852


Like I have been saying for years, you need REDUNDENCY- back up to the single stupid relief valve.

Got a car without an emergency brake lately?

I'll keep using the Park and the supplied emergency brake...

I'll Pass on carrying and using a wheel chock...

[jadnashua]

Got a car without an emergency brake lately?



Actually, the new car I just bought uses a computer driven hydraulic system for the parking brake...there is no direct mechanical lever or pedal to mechanically operate the brakes. If the engine is running, it works on all 4 wheels, if it's not, it only works on the rear wheels. You pull the little switch up to activate, and push it down to turn it off.

As we've gone over multiple times, the code approved method is an expansion tank along with the factory T&P valve. If doing more makes you feel better, go for it, but millions of people don't do more and their tanks haven't blown up, nor do I expect that they will.

[ballvalve]

Wheel chocks are required by law in many places for trucks because they are mechanisms in PLAIN SIGHT that do not fail.

And all my tractors and excavators have hydraulic acculumulators, seem to NEVER break or leak, and within a few seconds lock up all drive mechanisms when the engine is killed. As soon as you turn off a 100,000 pound excavator, you have nothing to do but go home, no levers to pull. Great system.

Very handy on the edge of a cliff when the engine dies and braking power ends. Might not work so well on a pickup at 80 MPH on the freeway.

A hydraulic accumulator on autos, with brains, would be a huge safety factor for braking and parking.

Funny how a backup relief valve disturbs everyone. But all those stupid backflow valves that we lived without for 150 years are gods new standard without question. How many of you got sick from reverse flow water? Better to regulate chickens in the market for bacteria.

[Redwood]

Funny how a backup relief valve disturbs everyone. But all those stupid backflow valves that we lived without for 150 years are gods new standard without question.

Because you propose it instead of a thermal expansion tank which is about the equivalent of us saying strip the brakes off your truck because they might fail and use "Fail Safe Wheel Chocks" instead....

The fact is your relief valves can and do fail quite often and plumbed to a drain and in a failed or, operational state could conceivably run full flow unnoticed until a well goes dry or, you have a heart attack when you open your water bill.

So jump off your engineer soap box and realize the data and logic you are applying to your brilliant solution is flawed badly.

That is why we repeat ourselves every time you mention this....

We will repeat it as often as you do, because bad advice does need to be exposed as such.

[ballvalve]

Sure expansion tanks help, when NEEDED, but they have the same pressure rating as the heater body, so blowing the internal bag is not back up like another pressure valve. You can do another myth busters video with a expansion tank in the circuit, and the simple question is which one blows first.

Unless you have 2 shut off valves on the water heater and a absent relief valve, the value of the exploding water heater videos is the same as a video showing what happens when you build your charcoal barbeque fire right under the gas tank of your motor home.

[Redwood]

Okay... Let me get this straight now...

If someone turns off the two valves on the inlet and outlet of the water heater... (Even though us plumbers don't put one on the outlet)

and...

If the T&P Valve fails..... which is easily tested and should be regularly.....

and...

If the Thermostat fails in a manner which causes heating continuously 50-50 chance....

and....

If the TCO (Thermal Cut Off) fails....

Oh Boy Mr Engineer... Just how much redundancy do you want anyway?

By your theory we've got your dump truck parked:

The emergency brake is set...

and

The engine is off and in lowest gear...

and

the wheel chocks are in place

and

the truck is on level ground....

All we can do now is take your silly azz little ball valve and throw it at the window breaking it....

Come on Ball valve grow some grey matter will ya?

[ballvalve]

Everyone must be bored around here.

My point was that the exploding water heater videos are fun, but almost irrelevant. As you well point out with all the other devices to be bypassed.

Leave out the hot shut off, and now you have lots of pipes and hoses that can become your pressure relief valve.

As to grey matter, dump trucks do not have nitrogen filled liquid hydraulic accumulators for the e-brake. And the dump truck driver with the most of it actually uses his wheel chocks.

In case you missed the POINT - expansion tanks provide no help with a run-away [tampered with] water heater.

[Redwood]

Everyone must be bored around here.

No, We are just tired of you the "Unknowing" spewing your lack of wisdom on this subject and determined to rebut the bad advice you consistently spew...

We have tried to educate you on the subject but due to a lack of absorbency your grey matter repels knowledge...

This is a common occurrence in some people in your chosen field. Most continue to educate themselves all through life and become very good in the field. Others blindly decide at some point that they know everything and at that point cease to have any value.


In case you missed the POINT - expansion tanks provide no help with a run-away [tampered with] water heater.

And your ball valve with a relief does?

If you will note at the product link (http://www.watts.com/pages/_products_details.asp?pid=564) you provided it states...

"It is for applications that require a means to shut off the water supply to the water heater and for providing protection from excess water pressure caused by thermal expansion."

Your assumption that it provides protection with a runaway water heater is completely out to lunch.

A properly sized T&P Valve will provide that protection. In looking at the specifications for the Watts 100XL T&P Valve you will not the following lines of information that do not appear on the product you recommend...

A.S.M.E Rated*, CSA Listed. Self-closing T&P Relief Valves
for Water Heaters up to 105,000 BTU/Hr.
The combined 2 in 1 T&P relief valve provides the least expensive and proven means for protection against both excessive
temperature and pressure emergency conditions.
Provides fully automatic temperature and pressure relief protection for hot water storage tanks and heaters up to 105,000 BTU/HR.

Each water heater and hot water storage tank shall be
equipped with a CSA and A.S.M.E. Rated* automatic temperature and pressure relief valve to protect the heater from excessive pressure and temperature. The device shall be ANSI Z21.22 certified. The BTU discharge capacity of the device
shall be in excess of the BTU input rating of the heater.

Now I'm not a General Engineering Contractor so I don't profess too have knowledge about digging irrigation ditches, land leveling, installing driveways, and ditch digging... Frankly I don't want that knowledge... I'll bow to your excellence or, hire some undocumented day laborers to do the work...

I'm a plumber! That is my area of expertise...
The engineers at Watts are a slightly different type of engineer than you are...
They have expertise in the safety controls needed on a water heater. So me the plumber having an awareness that you lack have decided that...

I will have a safety device that is CSA and A.S.M.E. Rated, ANSI Z21.22 certified, With a BTU discharge capacity in excess of the BTU input rating of the heater...

Now go dig a ditch or, something....

[Hillbilly Man]

Now go dig a ditch or, something....

Hot Dang Redwood!
Wat is it wit alla these engineeers that wanna think they knows mor bout plummin than Redwood.
They seems ta have no end to the line of em comin ta git ther noze bleedin.

[ballvalve]

The unknowing with repellant soft grey matter dont know the meaning of redundency and rely on granpas valves rather than the new choices in conjunction with the valve that comes installed on the heater.

Must be bored not having Ian to kick around lately. Glad to be of service.

[Redwood]

You give yourself way more credit than you are due...