Shutoff Valve in Hot Water Line of Water Heater

**Probedude** · 12-20-2008, 06:57 PM

Originally Posted by SewerRatz

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** · 12-20-2008, 07:10 PM

Originally Posted by 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?

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** · 12-20-2008, 07:12 PM

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** · 12-20-2008, 07:23 PM

Originally Posted by frenchie

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** · 12-20-2008, 07:33 PM

Originally Posted by RUGGED

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".

**GabeS** · 12-20-2008, 07:36 PM

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** · 12-20-2008, 07:52 PM

Originally Posted by 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.

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** · 12-20-2008, 07:53 PM

Originally Posted by frenchie

You had me at "retarded".

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

**Probedude** · 12-20-2008, 10:57 PM

Originally Posted by GabeS

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** · 12-21-2008, 09:28 AM

Originally Posted by 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?

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/w...dorderform.asp

**Probedude** · 12-21-2008, 10:38 AM

Originally Posted by SewerRatz

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** · 12-22-2008, 07:38 AM

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** · 05-17-2011, 01:10 PM

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** · 05-18-2011, 10:28 AM

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...ls.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.