Thread: Minimum water heater temperature

Had a water heater with 110deg water temperture
Seems that there is a minimun temperture required by code but I cannot locate the code. Will someone post the code if one exist.

Thanks

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HOT WATER.

Water at a temperature greater than or equal to

110°F (43°C).

I found it under definitions in the residential code.

The recommendation from A.O. Smith manufacture of Hot Water Heaters and Hydronic Boilers is 120*F. minimum unless you have a dishwasher installed then it is 140*F.
http://www.hotwater.com/lit/training/318181-000.pdf

Originally Posted by Robert Alfred Moller

The recommendation from A.O. Smith manufacture of Hot Water Heaters and Hydronic Boilers is 120*F. minimum unless you have a dishwasher installed then it is 140*F.
http://www.hotwater.com/lit/training/318181-000.pdf

Don't forget to read the other warnings before recommending to anyone to raise the temperature of the water heater for the dishwasher:
- see page 4
- see page 15
- see page 17 (no need to go any further - read the table for 1st and 3rd degree burns)

122 degrees F will create 1st degree burns 1 minute and 3rd degree burns in 5 minutes

140 degrees F will create 1st degree burns in 2 seconds and 3rd degree burns in 5 seconds

Looks like I neglected to thank James for his answer (over a year ago).
Thanks James

Originally Posted by Jerry Peck

Don't forget to read the other warnings before recommending to anyone to raise the temperature of the water heater for the dishwasher:
- see page 4
- see page 15
- see page 17 (no need to go any further - read the table for 1st and 3rd degree burns)

122 degrees F will create 1st degree burns 1 minute and 3rd degree burns in 5 minutes

140 degrees F will create 1st degree burns in 2 seconds and 3rd degree burns in 5 seconds

Whirlpool recommends a temperature of 140*F for proper dishwashers as well as NYC "Master Plumbers" code book.

A residential dishwasher needs 140-160°F (60-70°C) degrees for proper cleaning. Germs love anything less then 140°F (60°C).
When doing a combination occupancy like a commercial establishment with residential apartments using the same domestic H/W use a commercial heater giving an out put of 180°F (82°C) water.
You need 160°F (70°C) water for washing and 180°F for sterilization in lieu of chemicals. Water below 125°F (52°C) will allow all types of germs to grow inside the hot water tank (called incubators). So they sued everyone until the manufacturers lowered the residential water heaters to a very unsafe level.
The solution to the temperature dilemma is to use a quality mixing valve to allow VERY hot water to go to the dish washer and laundry machines to actually kill GERMS and use these tempering valves to control the temperature of the water after these devices to go throughout the system.
Now when this hot water does reach a shower-body or faucet you can add the following safety devices that are used with great success called pressure/temperature regulating/valves or balancing valves etc.
What these devices do is protect the user from being scalded when someone else flushes a toilet and the pressure drop is acted upon with no chance of the user being burned.
The same when the hot water is used say in a dish washer this sudden drop in temperature Or pressure will not shock someone in a shower.
Years ago when water was heated by the cave dwellers over a pile of wood in a pot around a camp fire the parents TESTED the water before throwing a child in. Still a good idea!

Originally Posted by Robert Alfred Moller

Whirlpool recommends a temperature of 140*F for proper dishwashers as well as NYC "Master Plumbers" code book

Originally Posted by Jerry Peck

140 degrees F will create 1st degree burns in 2 seconds and 3rd degree burns in 5 seconds

Soooo ... what are your going to recommend to your client?

No way would I recommend turning up the temperature, I would recommend replacing the dishwasher with one which has a 'Hot Start' feature ... oh, wait, we already have one which has that feature, bought it 5 years ago when I moved up here, did not cost much more than a regular dishwasher ... and I DO NOT NEED the water heater set to 140 degrees and I DO NOT have to risk 3rd degree burns in 5 seconds.

Make your choice - which would YOU recommend to YOUR clients?

Originally Posted by Jerry Peck

Soooo ... what are your going to recommend to your client?

No way would I recommend turning up the temperature, I would recommend replacing the dishwasher with one which has a 'Hot Start' feature ... oh, wait, we already have one which has that feature, bought it 5 years ago when I moved up here, did not cost much more than a regular dishwasher ... and I DO NOT NEED the water heater set to 140 degrees and I DO NOT have to risk 3rd degree burns in 5 seconds.

Make your choice - which would YOU recommend to YOUR clients?

Read the additional I added from the code book

A higher temperature to avoid biological growth farm (such as legonella) in a storage type water heater or a megastore, and a tempering valve "downstream" for supplying faucets.

Originally Posted by H.G. Watson, Sr.

A higher temperature to avoid biological growth farm (such as legonella) in a storage type water heater or a megastore, and a tempering valve "downstream" for supplying faucets.

Amen. to that statement. Remember "Legionnaires Disease"

Originally Posted by H.G. Watson, Sr.

and a tempering valve "downstream" for supplying faucets.

"Upstream of" the faucets. (Just clarifying the "downstream for" the faucets.)

I've been waiting for him to think of that.

There is nothing wrong with having a water heater set at 120 degrees, and having a dishwasher made to do what it is supposed to do - wash dishes with hot water. With that, there is no need to set the water heater to a high temperature of 140 degrees.

Now, with a tempering valve, you could install a tee off the hot out from the water heater and run one outlet to the dishwasher for super hot water, and then the other outlet to a tempering valve to supply the rest of the house.

However, without a tempering valve there is no reason to raise the temperature of the water heater just to accommodate a dishwasher - make the dishwasher do what it should do - heat its own water to a suitable temperature, then no one needs to worry about the other hot water throughout the house.

Originally Posted by Jerry Peck

"Upstream of" the faucets. (Just clarifying the "downstream for" the faucets.)

I've been waiting for him to think of that.

There is nothing wrong with having a water heater set at 120 degrees, and having a dishwasher made to do what it is supposed to do - wash dishes with hot water. With that, there is no need to set the water heater to a high temperature of 140 degrees.

Now, with a tempering valve, you could install a tee off the hot out from the water heater and run one outlet to the dishwasher for super hot water, and then the other outlet to a tempering valve to supply the rest of the house.

However, without a tempering valve there is no reason to raise the temperature of the water heater just to accommodate a dishwasher - make the dishwasher do what it should do - heat its own water to a suitable temperature, then no one needs to worry about the other hot water throughout the house.

FYI In New York Tempering Valves are required by Code

Originally Posted by Robert Alfred Moller

FYI In New York Tempering Valves are required by Code

For how many code cycles back and what is the average age of the houses you inspect?

Originally Posted by Jerry Peck

"Upstream of" the faucets. (Just clarifying the "downstream for" the faucets.)

I've been waiting for him to think of that.

There is nothing wrong with having a water heater set at 120 degrees, and having a dishwasher made to do what it is supposed to do - wash dishes with hot water. With that, there is no need to set the water heater to a high temperature of 140 degrees.

Now, with a tempering valve, you could install a tee off the hot out from the water heater and run one outlet to the dishwasher for super hot water, and then the other outlet to a tempering valve to supply the rest of the house.

However, without a tempering valve there is no reason to raise the temperature of the water heater just to accommodate a dishwasher - make the dishwasher do what it should do - heat its own water to a suitable temperature, then no one needs to worry about the other hot water throughout the house.

The subect was minimum water heater temperature.

I said: "A higher temperature to avoid biological growth farm (such as legonella) in a storage type water heater or a megastore, and a tempering valve "downstream" for supplying faucets."

Higher temperature at the water heater to avoid biological growth

a tempering valve "downstream" (OF THE SUBJECT, defined in my statement as a storage-type water heater or a Megastore")

for SUPPLYING faucets (supplying those faucets indicates "upstream" of said faucets).

tempering valve(s) to supply faucets IS CLEAR - the supply of faucets IS necessarily before, or rather "upstream" of the faucet output/point of use.



Yes there IS something wrong with it. 120 degrees F, esp. with temperature fluctions and the range of accuracy of same, is a perfect "biological farm" for many disease causing bacteria. Set point of 110 is even worse for the thermo heat point.

There are other means to remedy/regulate/safely modulate point of use hot water temperature safety - relying upon the gas valve or thermo system setting or elements of the water heater tank for temperature safety, scald/burn protection is not a reliable or safe method for protection/safety of persons from scalds/burns.

Setting temp so low for a storage-type water heater, is not ideal for a safety standpoint of a potable hot water supply system, esp. where point of use aeration, doing so is a false and incomplete method - as can NOT be relied upon for safety (sediment, scale, temp ranges of accuracy, etc.) from scalds/burns, and further creates a perfect incubator for bacterial growth.

Originally Posted by Jerry Peck

For how many code cycles back and what is the average age of the houses you inspect?

I.m not an inspector rather a Licensed HVAC/R Technician and Instructor.
We are required to have both a limited Plumbers and Electrician License and this is what is a requirement on the test. They also ask about "Lead Bends"
Whether they are right or wrong this is what they want. I won't even mention the "Electricians" test.

Please read the following which appeared on "Heating Help.Com"

3 die of rare brain infection from amoeba in water - Yahoo! News

Originally Posted by James Duffin

HOT WATER.

Water at a temperature greater than or equal to

110°F (43°C).

I found it under definitions in the residential code.

I think you have got the answer...for my dish washer takes the same code..

In the past I kept my heater at about 125F, but would continually get an annoying sulphur smell and would have to use hydrogen peroxide and flush the tank.

Recently I have turned the tank temp up to 140F and finally that seems to have solved the problem.

Up here it is now code requirement to have temp at 140F with tempering valve in new construction.

Go gas tankless.

I rarely use my dishwasher because I prefer to wash dishes as I use them. I just have a two-person household. I've always wondered why dishwashers require hotter water. All my life I've been washing dishes by hand and never been sick from germs. Maybe the extraordinarly hot water wears out dishwasher components faster so that you have to buy a new dishwasher more often. How I love planned obsolescence.

Originally Posted by Russel Ray

I've always wondered why dishwashers require hotter water. All my life I've been washing dishes by hand and never been sick from germs.

If you operated a restaurant or a hospital, dishwashing by hand would spread germs to everybody that ate there.

Maybe you've never been sick by germs but you have been exposed to plenty of germs. Just not the really bad ones like typhus , hepatitus, etc. If it wasn't for commercial dishwashers and paper and cardboard food wrappers, you might not have been so lucky.

Originally Posted by John Kogel

If you operated a restaurant or a hospital, dishwashing by hand would spread germs to everybody that ate there.

Maybe you've never been sick by germs but you have been exposed to plenty of germs. Just not the really bad ones like typhus , hepatitus, etc. If it wasn't for commercial dishwashers and paper and cardboard food wrappers, you might not have been so lucky.

What about all the people who don't have dishwashers? Probably 10-15% of my inspections are in homes that still don't have dishwashers, nor disposals.

Originally Posted by Russel Ray

What about all the people who don't have dishwashers? Probably 10-15% of my inspections are in homes that still don't have dishwashers, nor disposals.

I didn't say you need to have a dishwasher in your home to be healthy. They help to stop the spread of disease, because of the high water temp. That's all.

Originally Posted by John Kogel

I didn't say you need to have a dishwasher in your home to be healthy. They help to stop the spread of disease, because of the high water temp. That's all.

I'm not convinced. I think they are merely a convenience.

Originally Posted by Russel Ray

I'm not convinced. I think they are merely a convenience.

Not in a commercial environment (as mentioned in the posts you've responded to). They are required for the reasons already listed, and the appliance's water temperature is one of many safety items that's checked.

Originally Posted by Dom D'Agostino

Not in a commercial environment (as mentioned in the posts you've responded to). They are required for the reasons already listed, and the appliance's water temperature is one of many safety items that's checked.

I'm not convinced of that either. It's a simple matter that a dishwasher anywhere can wash dishes faster than a person can.

Safe Dishwashing - Food Safety - Leeds, Grenville and Lanark District Health Unit
NSF Consumer Information: Newsroom: Safer Home Fact Kit: Selecting a Residential Dishwasher
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Originally Posted by Russel Ray

I'm not convinced of that either.

Contact your Dept. of Health and they'll supply you with very specific requirements for handling glassware and dishes and the temperatures needed for safe handling. If you hand wash, you must meet specific temperature and sanitization levels.

See the post above from Raymond for some examples.