# Using a Mixing Valve on Water Heater



## user2090 (Sep 26, 2009)

I know that Bradfordwhite offers upgrades that go along with their new Icon set up. 

I have a job that I am offering different solutions, and while on the Lochinvar website, I came across a diagram for a mixing valve, and it got me thinking. 

Would a 50 gallon natural gas heater with a mixing valve, and raised temperature be adequate to provide for a whirlpool tub? 

Thoughts.

Does or has anyone used a mixing valve on a residential application?


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## nhmaster3015 (Aug 5, 2008)

Maybe yes, maybe no. You would have to know the incoming pressure along with pipe diameters and lengths and the flow of the tub filler also. However, raising the temperature and mixing down is a good way to get rid of legionella bacteria (though not completely thourough) It's one of those things that's worth a try anyway.


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## easttexasplumb (Oct 13, 2010)

My supply house had an advertisement for a new quick connect mixing valves for W.H. I thought it was a good idea at first, but dont really like the idea of turning up a heater very high. Around here some water heaters are in weird places, no where for T&P relief to drain to.


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## ZL700 (Dec 8, 2009)

Yes

This explains it easily:

http://www.forwardthinking.honeywell.com/related_links/water/mixing_valve/sell/63_9381.pdf


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## nhmaster3015 (Aug 5, 2008)

There is a video on the Watts.com web site called "danger, scalding lurks" it is worth the time it takes to watch it.


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## ZL700 (Dec 8, 2009)

Of course it is important to choose a proper mix valve (domestic not radiant) which includes ASSE 1017, assuring it will fail cold.


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## user2090 (Sep 26, 2009)

The more I think about it the more I am liking the idea. As long as it is a fail to cold device. What concerns me is, why haven't I heard much about this method before? 

Are fail to cold a newer idea?


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## Lifer (Nov 23, 2010)

We use them here to temper the water when using a Coil on a boiler for domestic use (180* ) the Watts ones are inexpensive but junk . I like the ones made by Honeywell they are around 125 bux here but worth the money if you need one ...

Why not do this everywhere , I think it just comes down to cost and need . Most people will just put in a larger HWT if they are gonna need more hot water, Also HWT's are designed to work well and perform for a long time at a given range ( not too long lol ) but if you start changing the temps on them you will shorten the life span of the tank..

If someone just upgraded there bathroom and have a newer tank than I don't think it would be a bad option . But at 125 bux for the valve and the cost of piping it up I think you would be better off to up-sell the HWT it would be a better option for the long run and not really that much more money..

Proper equipment for the Proper job..
just my .02 $
Lifer...


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## user2090 (Sep 26, 2009)

Lifer said:


> Why not do this everywhere , I think it just comes down to cost and need . Most people will just put in a larger HWT if they are gonna need more hot water, Also HWT's are designed to work well and perform for a long time at a given range ( not too long lol ) but if you start changing the temps on them you will shorten the life span of the tank..
> 
> 
> Proper equipment for the Proper job..
> ...


I called and talked to tech support with Lochinvar and they said it should not cause any problems. They are not liable for any engineering done with the pipes, but raising the temp does not effect warranty. 

Realistically what are we talking about, 15 degrees at most. More like 10


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## RealLivePlumber (Jun 22, 2008)

Tend to agree with Lifer, for the most part. I don't see how it would shorten the life of the tank, to up the temp to say 150, then temper to 115 for domestic use. 

I don't know how much more tempered (hot) water you would get, in terms of volume. You might only get an extra 5 gallons. 

I think the for the added cost, just upgrade the WH. 

Bradford's, GX series comes with a mixing valve in the box. They run them @ 180 degrees. I have installed a few. Worked great in those situations. (2nd floor condo beach house, Unable to increase gas piping size, making tankless impossible, and the other was a full finished basement, sheetrock ceilings, and they added a big azz jacuzzi in the master.) They are a larger btu input, I think like 70K, so they recover faster. 

But the biggie is that Bradford White has designed the system, and it meets a standard, whether it be ANSI, of ASME, or whatever. I am not going to engineer and install a system that is not approved, and be on the hook if something happens.


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## Lifer (Nov 23, 2010)

I guess i am thinking of a little hotter temp increse and also 90% of the hwt's in my area are electric... hotter is harder on the elements ( more run time ) 

But i can't see a 10 % rise in water temp hurting a tank or being worth the cost of a mixing valve ..
Lifer...


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## 1703 (Jul 21, 2009)

The formula for figuring the fraction of hot water required to produce a desired temperature is-

mixed temp minus cold temp
hot temp minus cold temp

So assume a mixed temp of 120, a hot temp of 150 and a cold temp of 60

120-60= 60
150-60= 90

If i did that right, 2/3's of your mixed water would be hot under those circumstances. 

What's that mean? I don't know, but i think it will stretch a tank of hot water farther than I originally thought.


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## ILPlumber (Jun 17, 2008)

I do this on every WH I install. 

A third more hot is a good rule of thumb.......

Tempering valves are smart CYA business in general though.


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## Protech (Sep 22, 2008)

Fuel consumption will go up. Tank life will go down.

Sent from my droid x


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## ILPlumber (Jun 17, 2008)

Protech said:


> Fuel consumption will go up. Tank life will go down.
> 
> Sent from my droid x


I agree with the first sentence.

Sent from my desk.


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## Plumbdog (Jan 27, 2009)

Put one every WH I install electric or indirect. Good for the profit margin and the customer likes getting more hot from the same size tank.


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## Protech (Sep 22, 2008)

Hotter water=faster corrosion and fastwr mineral buildup. Fact.

Sent from my droid x


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## ILPlumber (Jun 17, 2008)

Protech said:


> Hotter water=faster corrosion and fastwr mineral buildup. Fact.
> 
> Sent from my droid x


 
I think you are splitting hairs.

"Mam, I checked your anode. I'm afraid we are going to have to lower the temp 15 degrees" 

Sent from my laptop using my text inputing monkey "Marcel"


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## user2090 (Sep 26, 2009)

We are talking about a maximum difference of 15 degrees, how could that make that much of a difference. I emailed BW and will wait for their response. Unless I can find some hard evidence beforehand.


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## rombo (Jul 17, 2008)

What temps is everyone usually setting their tanks at?


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## Protech (Sep 22, 2008)

:laughing:



ILPlumber said:


> I think you are splitting hairs.
> 
> "Mam, I checked your anode. I'm afraid we are going to have to lower the temp 15 degrees"
> 
> Sent from my laptop using my text inputing monkey "Marcel"


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## Protech (Sep 22, 2008)

Indie said:


> We are talking about a maximum difference of 15 degrees, how could that make that much of a difference. I emailed BW and will wait for their response. Unless I can find some hard evidence beforehand.


It won't make that big a difference


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## user2090 (Sep 26, 2009)

rombo said:


> What temps is everyone usually setting their tanks at?


I leave them at the factory setting, which is supposed to be no more than 125. I think it is closer to 120, but its in that general area. So, if you boost it up to lets say 140, is it that big a leap?


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## rombo (Jul 17, 2008)

Well in Ontario we are required to have tanks set at 140 due to worries about legionnaires disease. There for every new install requires a mixing.


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## rombo (Jul 17, 2008)

For the record our factory temps are set at 140 95% of the time.


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## user2090 (Sep 26, 2009)

rombo said:


> Well in Ontario we are required to have tanks set at 140 due to worries about legionnaires disease. There for every new install requires a mixing.



I hope others chime in on this, cause I know for now that there is no code for that in Indiana.


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## GREENPLUM (Jul 27, 2008)

how did you figure that a 15* increase with a tempering valve will fill up the tub ? :blink: 


how big is the ****in tub?


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## ZL700 (Dec 8, 2009)

I read this in a periodical recently and dug it back up:
Read the bottom concerning Canada 

*

Hot Water Temperature, Scalding, and Legionnaires’ Disease

Hot water temperature and its impact on the incidence of scalding and Legionnaires’ disease is a hot topic in the industry at the moment. The issue is being discussed at Plumbing Code hearings and not a month goes by that the subject is not mentioned in the trade magazines. We have assembled a range of information here related to the issues. We hope you find it interesting and informative.

Scalding Facts

Destroying the bacteria that causes Legionnaires’ disease requires raising the temperature of water to at least 140°F (60°C).
But, at the temperature 140°F (60°C), water can cause third-degree burns in children in one second and adults in five seconds.
The U.S. Consumer Product Safety Commissions states that approximately 3,800 injuries and 34 deaths are directly related to dangerously hot tap water in residences (The National Safe Kids Campaign lists the number of scalding injuries as high as 6,500).
The answer to preventing both Legionnaires’ disease and harmful water temperatures is to store the water at a high temperature and temper it to a safer temperature before distribution to the fixture.
Legionella Facts

Legionnaires' disease acquired its name in 1976 when an outbreak of pneumonia occurred among persons attending a convention of the American Legion in Philadelphia.
The bacterium is spread through inhalation, which can occur while showering, washing or drinking the water.
An estimated 8,000 to 18,000 people get Legionnaires' disease in the United States each year (5% - 30% of the cases are fatal).
Legionnaires' disease can cause fever, chills, and a cough, which can be dry or may produce sputum. Some patients also have muscle aches, headaches, tiredness, loss of appetite, and, occasionally, diarrhea. Legionella may also cause cases of pneumonia that may be difficult to diagnose.
Improved design and maintenance of cooling towers and plumbing systems to limit the growth and spread of Legionella organisms are the foundations of preventing the disease.
Ideal Conditions For Legionnaires’ Disease

Legionella Pneumophilia, the bacteria that causes Legionnaires’ disease, thrives in warm, stagnant water.
A water temperature of 120°F does not kill the bacteria; a minimum temperature of 140°F is required.
A water heater set at 120°F can contain water as low as 100°F.
To eliminate the bacteria, several steps need to be taken, including eliminating dead-legs and system flushing. But, without a storage temperature of 140°F, all other steps cannot solve the problem.
Legionnaires’ Disease in Residential Environments

In a recent test, 24% of a 21-family test group was found to have Legionella bacteria in their home water.
A combination of new and old research now suggests that the bacteria may thrive in residential hot water pipes, and the water supply used in residential homes may be directly responsible for 20% of Legionnaires cases.
Bacteria in natural water sources (not unlike those used by residential dwellings) do not undergo the processes of filtration and chemical disinfection that municipal water supplies go through. Instead, natural water sources must be treated by the private owner, a process which is often inconsistent or incomplete.
Canada Leaps Ahead of the U.S.

A change has recently been made to Canada’s plumbing code that requires water supplied to fixtures in residential buildings to be a maximum temperature of 49°C (120°F).
The change is expected to be adopted by January 2004 and fully implemented by mid-2004.
The reasons for changing the code are listed specifically as the prevention of scalding and Legionnaires’ disease.
The solutions stated in the code are installing a TAFR device, a mixing valve at each individual fixture or a master mixing valve at the water heater.


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