Do you set up your hot water storage tanks properly?

GreenGene

https://www.youtube.com/watch?v=IY0v5YGZNpc

GreenGene

Put this in your search engine.

hot water heater bacteria

and read the hits

ChrisJ

I run my tank at 140F, partially for this reason. That and it cleans dishes really really well. I also would not install a mixing valve at the heater because bacteria has been known to grow in hot water piping as well, an occasional good cooking at 130-140F should prevent it.

However, is this a concern with city water that has chlorine in it? I can see it being a concern with well water, but can anything live in city water?

Rich_49

EPA tested municipal water systems 2 years ago and found that roughly 50% had legionellosis . Putting a mixing valve at the heater which stores water at a temp which is known to kill legionella is not a concern , if they are all dead they cannot multiply At a point further into the system .

ChrisJ

Rich said:

EPA tested municipal water systems 2 years ago and found that roughly 50% had legionellosis . Putting a mixing valve at the heater which stores water at a temp which is known to kill legionella is not a concern , if they are all dead they cannot multiply At a point further into the system .

What happens when someone uses a lot of hot water and bacteria ends up leaving the heater alive? Seems very likely actually.

Wonder how much the typical 40 or 50 gallon heater drops while someone is taking a shower or fills a washing machine with hot water, or both.

Some clothes washers hold an awful lot of water.

ChrisJ

4Johnpipe

We typically store at 150 and mix down with a TMV to the house. All heaters are static for at least a half hour a day. That would kill anything in the tank. Once water is moving the bacteria can't multiply / colonize and at 150 it's dead real soon. The side effect is more hot water available and cheaper fuel bills.

ChrisJ

4Johnpipe said:

We typically store at 150 and mix down with a TMV to the house. All heaters are static for at least a half hour a day. That would kill anything in the tank. Once water is moving the bacteria can't multiply / colonize and at 150 it's dead real soon. The side effect is more hot water available and cheaper fuel bills.

Until the tank drops down to 130 or 140 and it takes minutes to kill the bacteria and some flows from the dip tube into the hot water outlet. Once in the piping it will be allowed to multiply no?

Mixing valves at fixtures seem fine, but at the tank seems like it could cause a problem. Not only that, many appliances such as dishwashers like 140-150F so even without bacteria I feel it's best to put the valves at fixtures if you're going to use them.


Fact is, I'm no more of an expert on this as anyone else, so there's a always a chance my opinion is wrong.

4Johnpipe

We run direct lines to dishwashers in some cases. They only need 120 though. Example first fill on new tank. It runs to 150 or 155. Legionella dead after 15 minutes. Add water it's moving now. Tank comes on 7 degrees cooler than set point. Water flowing stops. Tank heats up kills any new bacteria. Keeping valve closer to source prevents bacteria from entering system.
It's also code now.

ChrisJ

4Johnpipe said:

We run direct lines to dishwashers in some cases. They only need 120 though. Example first fill on new tank. It runs to 150 or 155. Legionella dead after 15 minutes. Add water it's moving now. Tank comes on 7 degrees cooler than set point. Water flowing stops. Tank heats up kills any new bacteria. Keeping valve closer to source prevents bacteria from entering system.
It's also code now.

True dishwashers only need 120, but they work better with hotter. Most, if you only feed 120 will run their internal heater to bring the water up to temp.

My parent's Bosch actually changes it's cycle times substantially based on how hot the supplied water is.

njtommy

What about UV lights for water treatment do they help or even work?

Rich_49

Lucky for me and most of our clients that we usually install recirc lines . Makes it kind of a non issue .

Don't worry though ChrisJ and GreenGene , DOE and the efficiency geniuses will keep telling everyone to turn the temp down to save energy .

Keep in mind though that most atmospheric heaters have much hotter water above the valve to the top of the tank . This is exactly why we are told that we cannot use the water heater temp controls as scald protection . Stored hot enough the average water heater is quite effective at protecting you much more than without . Storing at higher temps and using the mixing devices are our best defense at present .

SWEI

njtommy said:

What about UV lights for water treatment do they help or even work?

Quite well, actually -- according to the studies I have read.

Rich said:

Lucky for me and most of our clients that we usually install recirc lines.

If you add a UV sterilizer to that recirc line you are doing a favor to your clients. Oh, and you might even make a buck doing it. Sizing to the recirc flow rate makes them trivial in cost, and zaps the critters every time they come back around the circle.

GreenGene

I remember some seminar years ago where they said the best way is to run direct to dishwashers and washing machines and temper sinks/showers.

Seen quite a few health care facilities where, if memory serves they ran the tanks around 16OF or higher and then tempered the kitchen, laundry and domestic to separate temps, can't remember what they set the dw and laundry to though.

GreenGene

It just amazes me, 5-12,000 people die from it annually and many still install water heaters set to 120. I remember being told this in the late 80's, seems so odd it's not a code or enforced.

ChrisJ

GreenGene said:

It just amazes me, 5-12,000 people die from it annually and many still install water heaters set to 120. I remember being told this in the late 80's, seems so odd it's not a code or enforced.

My wife has complained the water is too hot and I won't lower it.

The main issue, is our Delta faucet in the kitchen kinda sucks. It's either ice cold, or burning hot and very difficult to get any fine adjustment on it. It's a single lever style, where the lever is on the side instead of the top.

One day I'll replace it................

hot_rod

The key is to elevate the entire rec loop loop to at least 140F for a 1 hour period to assure all portions of the piping are exposed to high temperatures. That is how the standard in Europe works, and possibly that standard will be copied here.

But that brings up the issue of protecting all the fixtures when the loop is in high temperature mode. So more point of use mix valves we be needed.

GreenGene

I don't know, no expert on recirc loops, but wondering, assuming the tank would be the source, so as long as the loop was circulating and being used I'm not sure how much bacteria would grow in the recirc loop. When it returned to the tank anything that did start to grow would die.

However I think if a building or hotel, whatever was down for more than a few days then you'd have to assume you've got bacteria throughout the system.

GreenGene

OSHA has some information, in one section they state:
Water systems designed to recirculate water and minimize dead legs will reduce stagnation.

Pressure-independent, thermostatic mixing valves at delivery points can reduce delivery temperatures.

Point-of-use water heaters can eliminate stagnation of hot water in infrequently used lines.

Eliminate dead legs when possible, or install heat tracing to maintain 50°C (122°F) in the lines.

source: https://www.osha.gov/dts/osta/otm/legionnaires/hotwater.html

ChrisJ

GreenGene said:

I don't know, no expert on recirc loops, but wondering, assuming the tank would be the source, so as long as the loop was circulating and being used I'm not sure how much bacteria would grow in the recirc loop. When it returned to the tank anything that did start to grow would die.

However I think if a building or hotel, whatever was down for more than a few days then you'd have to assume you've got bacteria throughout the system.

Depends,
I believe most recirc loops have an aquastat so it depends on what that is set to.

The one I just installed for my parents is set to 125F with a 5F differential and the heater is set to 145 or 150 now. No mixing valves anywhere, it's what he wanted and that shuts the pump off when you get 125F to the end of the loop so most fixtures are much hotter.

My dad spent about a week messing with it until it was what he wanted. Was a mix of trying to get hot enough water instantly, and yet making sure the pump would still shut off when the heater was at the bottom of it's set temp range.

But both of us expect and like very hot water at our sinks. It seems many people don't so it would depend entirely on the person that sets it up and whoever is using it.

hot_rod

Even in my own home I'd be very careful with water that hot. A guest, child, etc could get a serious burn in a few seconds, especially with a recirc
giving you instant hot.

ChrisJ

hot rod said:

Even in my own home I'd be very careful with water that hot. A guest, child, etc could get a serious burn in a few seconds, especially with a recirc
giving you instant hot.

Can you hold your hand in 140F for 5 seconds?
5 seconds at those temperatures is an eternity. I'd give you a second or less before you pull your finger out.


It's a good point and I agree people need to be very cautious.

Gordy

Most of that danger comes from Bath tub incidents. With small children, and infants. Most people turn the shower on, and adjust before getting in. The same could be said for baths. However there are some, insert favorite word. Who would run a hot bath, and throw the young one in with out testing the water........

ChrisJ

Gordy said:

Most of that danger comes from Bath tub incidents. With small children, and infants. Most people turn the shower on, and adjust before getting in. The same could be said for baths. However there are some, insert favorite word. Who would run a hot bath, and throw the young one in with out testing the water........

Ugh.
That's even worse than just hopping in a shower without checking the water.

Trust me, you never do such a thing growing up in a house with really hot, hot water.

GreenGene

Hands are a little tougher than other parts of the body.

I got called years ago to install a tempering valve at a home, I asked the guy if he had children or why he wanted it, he said his mother in law lived with them, they went to work, she went to take a bath and as she turned on the hot water she had a stroke and fell in the tub, the hot water ran on her ankle all day and had to have an amputation.

hot_rod

Actually with the elderly it often turns into a slip and fall in addition to a burn. They try to jump back from a shower or tub and go crashing down.

If it raises a blister on the skin, it is considered 2nd degree and that's where the attorneys take over.

The lawsuit often names the plumber, manufacturer of the product, and the gas company or the supplier of the fuel.

Julius Ballanco is a engineer and expert witness in soft tissue lawsuits, he has plenty of stories regarding these suits. He presented a great webinar on this and the mis-use of recirc pumps on DHW with thermostatic valves.

Temperature Creep is what usually happens when recirc loops and thermostatic valves are not piped correctly.

Possibly the "soft tissue" attorneys will turn into legionella chasers with lowered temperature DHW systems.

ChrisJ

If adults cannot be trusted with hot water I guess they can't be trusted with hot pans in the oven either.

What about hot toast when the toaster first pops up?


If you can't be trusted with 140-150F hot water from a faucet, then you can't be trusted to take a cup of hot water (200+F?) out of a microwave oven either.

If the cup of boiling water is safe, then the hot water from a tap must be as well.

ChrisJ

GreenGene said:

Hands are a little tougher than other parts of the body.

I got called years ago to install a tempering valve at a home, I asked the guy if he had children or why he wanted it, he said his mother in law lived with them, they went to work, she went to take a bath and as she turned on the hot water she had a stroke and fell in the tub, the hot water ran on her ankle all day and had to have an amputation.

That's fine,
But what if she fell nose down? She would've drown so should we stop everyone from taking baths?

I understand the concern, but I don't agree with it.

JUGHNE

So where are the nasties created or born?? Are they lying dormant in the cold water just waiting for the correct incubator parameters to waken them. How do they get into any system to begin with? In any water between 95 and 115? The tank I speak of is at 140. The water to the resident rooms is tempered to 110 to 115, by state law requirement. The temp Valve is at the water heater. All the mixed water originates at 140 hot or 55 cold.

Considering the recirc circuit to return the water to the water heater: Most recirc water goes to the temp valve with minimal hot tank water added and is then sent out again. With low GPM draw the recirc water is blended with some cold and hot is added as needed.

Gordy

Legionella is everywhere. even the soil. Its when it is airborne in a fine mist that it becomes hazardous.

Paul48

Picture this, and this has happened...........You have the flu, and pass out getting into the shower. You hit the hot water handle as you fall, and your life is ruined.

hot_rod

Speaking as a licensed plumber, we sign on to "Protect the Health of the Nation" with the plumbing and mechanical codes as the law.

In the case of DHW scalding I imagine the codes are in place to protect young, old, the general public, or any that may not have the ability to handle or understand potentially dangerous conditions.

Customer, family, or friend, I would handle DHW temperatures the same.

ChrisJ said:

If adults cannot be trusted with hot water I guess they can't be trusted with hot pans in the oven either.

What about hot toast when the toaster first pops up?


If you can't be trusted with 140-150F hot water from a faucet, then you can't be trusted to take a cup of hot water (200+F?) out of a microwave oven either.

If the cup of boiling water is safe, then the hot water from a tap must be as well.

Gordy

I don't know how the human race has made it this far, with all the odds stacked against us............

Gordy

Paul48 said:

Picture this, and this has happened...........You have the flu, and pass out getting into the shower. You hit the hot water handle as you fall, and your life is ruined.

If you pass out with your mouth open, and you did not hit the shower valve to full hot you could drown. Or contract a lethal dose of legionnaires.

Paul48

We have survived thus far, in part, because we have embraced changes that make our lives safer.

Paul48

@Gordy

Easy enough to do with a single-handle, and 10 or 15 minutes under 150* water, you life and your families lives will never be the same. I believe it was a young lady that I read this about. There's nothing funny about it.

4Johnpipe

Posted by Robert Bean on FB just today...

hot_rod

Gordy said:

I don't know how the human race has made it this far, with all the odds stacked against us............

Some would say the opposite, the odds are stacked against the planet due to the human race

Gordy

Very true...

GreenGene

ChrisJ said
"That's fine,
But what if she fell nose down? She would've drown so should we stop everyone from taking baths?

I understand the concern, but I don't agree with it."

No, of course not, but fact is scalding is a major problem, especially with children and the elderly.

Hot Water Causes Third Degree Burns…
…in 1 second at 156º
…in 2 seconds at 149º
…in 5 seconds at 140º
…in 15 seconds at 133º.

Hot tap water accounts for 17% of all childhood scald hospitalizations.

GreenGene

I just read a Euro report on what they do which stated- "A number of states in the United States require water heaters be installed with the thermostat at 122F and studies there showed that the legislation has led to a reduction in tap water scalds with
no increase in cases of Legionnaires’ disease."

That is a complete lie, 122F is a perfect breeding ground for legionnaires’ disease. I've never heard of states requiring 122F either.