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Warning,Water Heater Safety

redsky49

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Jan 21, 2009
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near the coast in eastern North Carolina
For all those intent on raising the discharge temperature of your water heater, be advised of the risks:

From: http://www.cpsc.gov/cpscpub/pubs/5098.htm

Consumers can obtain this publication and additional publication information from the Publications section of CPSC's web site or by sending your publication request to [email protected].

Each year, approximately 3,800 injuries and 34 deaths occur in the home due to scalding from excessively hot tap water. The majority of these accidents involve the elderly and children under the age of five. The U.S. Consumer Product Safety Commission (CPSC) urges all users to lower their water heaters to 120 degrees Fahrenheit. In addition to preventing accidents, this decrease in temperature will conserve energy and save money.

Most adults will suffer third-degree burns if exposed to 150 degree water for two seconds. Burns will also occur with a six-second exposure to 140 degree water or with a thirty second exposure to 130 degree water. Even if the temperature is 120 degrees, a five minute exposure could result in third-degree burns.


At 145 degrees, a first degree burn will result from a 2.5 second exposure to this temperature in adults! In infants the time is less.

I would strongly recommend that water temperatures be limited to 110 degrees, or at the most 115. If you are experiencing poor performance at these setpoints you likely have another issue such as inadequate pipe insulation, excessive pipe runs, defective water heater, etc.

Please be safe, especially for children and the elderly. Posted as a result of discussions on another thread.

As always, offered only as opinion
 
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BillK

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Aug 24, 2006
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Beautiful Southern Maryland
Sorry Red ..... You just cannot get a good hot steamy shower with the temp at 110. Mine has been set at 140 for 30 years and I have not burned myself yet.
 

jgoglick

Active member
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Oct 17, 2007
Messages
42
OMG, the children..time to panick! Sorry, couldn't resist. Mine's set at 140 and I know how to mix cold and hot water, and so does my 5 year old (who is surpervised in the tub btw).
 
OP
R

redsky49

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Jan 21, 2009
Messages
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Location
near the coast in eastern North Carolina
While you may have the heater set at 140, I seriously doubt that you are receiving 140 degree water at the fixture. 140 degrees is really hot. Most likely it is much cooler. You cannot hold your hand in water at anywhere near that temperature. Try measuring the discharge temperature with a meat thermometer.

In any case, my intent was to alert those who may be at risk. Of course, do as you choose. Be safe.

:beer:
 

nate379

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Feb 2, 2009
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Palmer, AK
Mine is set to 130 or 135 as in that is what comes out of the faucet. I shower with it normally at wide open hot, once in a while a little bit of cold mixed in.

110* would be like a dog ******* on my back and calling that a shower. :shocking:
 

Ram

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Mar 4, 2010
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Location
Virginia
Maybe that is what the troops and sailors get out in the field and on ships but not me.
 

benjamming

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Jun 29, 2009
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Location
Alabama
OSHA Article on Legionnaires' Disease

Q. What water conditions are best for growth of the organism?

A. Warm, stagnant water provides ideal conditions for growth. At temperatures between 20°C-50°C (68°-122°F) the organism can multiply. Temperatures of 32°C-40°C (90°-105°F) are ideal for growth. Rust (iron), scale, and the presence of other microorganisms can also promote the growth of LDB.

--------------------------------------------------------------------------------

Q. Can Legionnaires' disease be prevented?

A. Yes. Avoiding water conditions that allow the organism to grow to high levels is the best means of prevention. Specific preventive steps include:
Regularly maintain and clean cooling towers and evaporative condensers to prevent growth of LDB. This should include twice-yearly cleaning and periodic use of chlorine or other effective biocide.
Maintain domestic water heaters at 60°C (140°F). The temperature of the water should be 50°C (122°F) or higher at the faucet.
Avoid conditions that allow water to stagnate. Large water-storage tanks exposed to sunlight can produce warm conditions favorable to high levels of LDB. Frequent flushing of unused water lines will help alleviate stagnation.

--------------------------------------------------------------------------------
Q. Do you recommend that I operate my home water heater at 60°C (140°F)?

A. Probably not if you have small children or infirm elderly persons who could be at serious risk of being scalded by the hot water. However, if you have people living with you who are at high risk of contracting the disease, then operating the water heater at a minimum temperature of 60°C (140°F) is probably a good idea. Consider installing a scald-prevention device.
 

babzog

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Eastern Ontario, Canada
:bs:

Mine is set at 140 - the factory preset output temp of the anti-scald valve. I dare anyone to hold their hand in that water for the 30s it takes to cause any sort of injury.. it will hut like hell before burning. I've had my hands in that water for much longer than 6s without burns and is usually what I put directly on my face to prep for shaving. I trust my kids not to be injured at that setting.
 

BioHazard

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Feb 3, 2010
Messages
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The front of my water heater at home says it's designed for 150* max. It's only at about 135, but I wouldn't hesitate to go to the "spec". If your water is too cold it will not sanitize your dishes...or anything else.

It's not just about outlet temperature either - the higher you crank the temp in your heater, the more WARM water you get, say, at 100 degrees. Like turning up the air pressure in an air tank.

My shop water heater was set at 110 when I moved in, I guess somebody was trying to save electricity, and it was laughable. Now I've got it cranked up to about 145.

The only way I could really see an issue with this is if the plumbing in your house is bad enough that the shower goes hot if somebody flushes the toilet. That could burn somebody...but most modern houses have better plumbing than that. I think they make anti-scald devices for showers, don't they?
 
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BioHazard

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OSHA Article on Legionnaires' Disease

Q. What water conditions are best for growth of the organism?

A. Warm, stagnant water provides ideal conditions for growth. At temperatures between 20°C-50°C (68°-122°F) the organism can multiply. Temperatures of 32°C-40°C (90°-105°F) are ideal for growth. Rust (iron), scale, and the presence of other microorganisms can also promote the growth of LDB.

I wonder if it wouldn't be a good idea to crank your water heater up to the max every once in a while just to kill anything that might be in there? :shocking:
 
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kaffine

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Dec 13, 2009
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Henderson, NV
They make tempering valves that you can put on the water heater that mixes cold water with the hot water out of the tank. This way you can run the tank at 140 degrees yet have the output water limited to 120 degrees or lower. This makes sure no one gets burned by hot water and the water temp in the heater is high enough to kill micoorganisms.
 

sdowney717

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Mar 17, 2010
Messages
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dont the newer shower valves have temperature limiting valves?
There are many cases of young children badly burned in the kitchen sink.
Temperature limiting valves ought to be standard on all faucets.
It is designed to mix cold into the hot when the hot temp exceeds a set value.
 

Dmaxman

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Jan 20, 2009
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Montreal, Canada
Have a buddy who burned his hand from hot water. He was doing some work on a hot water tank, not sure what he did but he got burned. The temp most have been cranked up. His hand still feels funny he tells me from the nerve damage.

mikeshand.jpg
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BioHazard

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Have a buddy who burned his hand from hot water. He was doing some work on a hot water tank, not sure what he did but he got burned.
But the same thing can happen when you're simply cooking dinner, can't it?

Maybe your water heater can burn you but it can also electrocute you or blow you up with gas if you're working on it or something is wrong. Seems like hot water should be the least of your worries. (And you should never work on a water heater when it's hot)
 

Shadowdog500

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Dec 7, 2009
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Down the shore
I agree that you don't want to scold yourself. You may also want to check the pressure relief valve once in a while to make sure the tank don't explode if there is a pressure spike. I test mine whenever I am near the heater, which comes to once or twice a year.

Here is a neat video of tank explosions: http://www.waterheaterblast.com/waterheaterblast.wmv

Here is the mythbusters version. The first tank just had a seam failure but the other two launched like moonrockets.

<object width="480" height="385"><param name="movie" value="http://www.youtube.com/v/pu3FwgIHsQA&hl=en_US&fs=1&"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/pu3FwgIHsQA&hl=en_US&fs=1&" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="480" height="385"></embed></object>


Mythbusters tests a bigger tank:

<object width="480" height="385"><param name="movie" value="http://www.youtube.com/v/rGWmONHipVo&hl=en_US&fs=1&"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/rGWmONHipVo&hl=en_US&fs=1&" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="480" height="385"></embed></object>

Chris
 
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Falcon67

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Jun 11, 2009
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Merkel, TX
We have ours set at 140F. If you have children or are worried about bath accidents, install temp limiting shower/bath fixtures. I redid the bathrooms before our grandson was born and installed the one knob units - worth the hassle. It also appeals to my lazy azz - turn knob full, shower, turn knob off, get out. No fiddling LOL.
 

Daniel Dudley

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Sep 4, 2009
Messages
3,546
It's no joke, especially for babies. Didn't someone recently post about a child getting burned by Hot water ? Anti scald valves are the way to go.
 

ddawg16

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Jul 11, 2008
Messages
21,005
Location
S. California
We have ours set about 115-120...the youngest is now 4.....like Nate, I shower with it at full hot....

My oldest boy is getting into taking showers....the younger ones always get into the bath first and then turn on the water...and don't hesitate to turn it colder if it gets to warm....

As soon as I do the addition to the house the temp will get cranked up....

As for dishwashers....mine has a heater to post heat the water.
 

sickboi55

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May 3, 2008
Messages
185
115, a concern. REALLY?!?!?!?!?! i deploy to places hotter than that, sheesh.
 

tcianci

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Feb 7, 2009
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Location
Walpole, Ma
There is a difference between thermostatic control of shower valve temperature and an anti-scald device. The anti-scald shower valve was invented in Boston in the 1930's by a guy named Symmons, yeah the company that still makes the shower valves today. The principal of operation is a pressure sensing device inside the stem of the valve. This pressure balancing device senses a pressure drop on the cold side of the water supply and uses this change in pressure to throttle the amount of hot water being delivered through the valve. The result is noted as a reduced flow from the valve that is proportional to the reduced amount of cold water pressure available. The hot water being throttled back because of a cold water pressure drop keeps the temperature of the outlet water in a safe range.
Shower valves also have a temperature limit stop which is supposed to be set by the installer. It is a screw that is accessed under the valve trim and limits the maximum temperature of the valve.

There are also shower valves that are thermostatically controlled... you set the temperature with the control handle and the valve maintains the temperature via an internal thermostat which constantly controls the mix of hot and cold water coming out of the valve.
 
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