# do all thermostatic mixing valves lag.



## justin (May 14, 2010)

i am always having problem with my thermostatic mixing valves not keeping up. i use a 2" mixing valve and it is rated to supply around about 600 wfu. i always bypass mixing valve and turn tmv hot off and just use cold. it mixes after bypass where it is 2.5 or 3" copper back to fixtures. it just seems like you can never get them to work right. any helphttp://www.plumbingzone.com/attachment.php?attachmentid=6803&stc=1&d=1279503538 hope this pic came out. if it didnt then i can try again. just trying to show the installation. thanks


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## nhmaster3015 (Aug 5, 2008)

If that's a Leonard valve they can be a bit tricky. They have a habit of sticking internally where the element rides on the glides. Take it apart and clean the hell out of it and make sure the inlet flow is adjusted properly. Leonards site is pretty helpful if you don't have the instructions.


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## justin (May 14, 2010)

nhmaster3015 said:


> If that's a Leonard valve they can be a bit tricky. They have a habit of sticking internally where the element rides on the glides. Take it apart and clean the hell out of it and make sure the inlet flow is adjusted properly. Leonards site is pretty helpful if you don't have the instructions.


yes its a leonard. and its like a virus on these things. thanks.


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## mongo (Jun 26, 2010)

ALL mixing valves have given me fits. If there is not circulating line on the HW supply, it might take 20-30 seconds for the last fixtures to get hot. 

I just install 85 Honeywell UMV (point of use) mixing valves at a new high school. The valve has internal checks on both hot and cold water but they still will allow hot water to cross over to the cold side. This results in hot water coming out of the cold side for about 5 seconds when it is first turned on.


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## 1703 (Jul 21, 2009)

That's a big valve. It may be having trouble reacting to a small flow like one lav. 

Its my understanding that most tmv's need a flow near capacity to operate correctly. 

Bigger is not necessarily better when it comes to mixing valves.

But I also agree with NH. Make sure all parts are moving freely. 

Good luck.


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## justin (May 14, 2010)

Colgar said:


> That's a big valve. It may be having trouble reacting to a small flow like one lav.
> 
> Its my understanding that most tmv's need a flow near capacity to operate correctly.
> 
> ...


I have a fifty gpm. Circ pump pushing through 4 heaters and then the tmv. So the flow is at a constant for the application, but it is the same story over and over. It kind of defeats the purpose of having one.


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## ILPlumber (Jun 17, 2008)

Show me a pic of the recirc piping arrangement.

Leonard is over-priced crapola IMO.


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## ILPlumber (Jun 17, 2008)

Also, why are there di-electric unions on it?


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## justin (May 14, 2010)

Matt said:


> Also, why are there di-electric unions on it?


I think Red brass is 85 percent copper and 15 percent zinc. I am just cautious. I have seen electrolysis on copper to brass. The 15 percent is what gets me. I am on my phone typing this but I would be more than happy to post a pic of the pump application when I get back in town to comp. Thanks .


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## nhmaster3015 (Aug 5, 2008)

Justin, does the temperature creep up after the fixtures shut off?


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## justin (May 14, 2010)

nhmaster3015 said:


> Justin, does the temperature creep up after the fixtures shut off?


Not on this one. But I have noticed that on a couple others I've installed. Very inconsistent. What ya think??


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## 1703 (Jul 21, 2009)

justin said:


> I have a fifty gpm. Circ pump pushing through 4 heaters and then the tmv. So the flow is at a constant for the application, but it is the same story over and over. It kind of defeats the purpose of having one.


judging by your pics, the circ'd hot water is sent through the mixing valve via the hot inlet?

and what exactly do you mean by "not keeping up"?

Does that mean your not circulating circulating tempered water? tempered line goes cold?


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## justin (May 14, 2010)

Colgar said:


> judging by your pics, the circ'd hot water is sent through the mixing valve via the hot inlet?
> 
> and what exactly do you mean by "not keeping up"?
> 
> Does that mean your not circulating circulating tempered water? tempered line goes cold?


No, just losing volume at peak times. But when bypassed it does fine. Yeah circ pulls from 3 floor and pushes through heaters then on to tmv.


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## 1703 (Jul 21, 2009)

What is the exact model of the mixing valve?


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## ILPlumber (Jun 17, 2008)

Is the return piped to the cold feed of the WH as well as the cold feed of the mixing station?

Is the water moving through the TMV too quickly? 

where are the check valves?

I put a drawing of a properly piped circulating TMV system up a long time ago. Search it and compare to what you installed. 

I despise High/low valves. I also despise how often the leonard valve requires maintenence......

I'll see if I can search for the iso....


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## ILPlumber (Jun 17, 2008)

I can't find it. Do you remember the argument about the constantly running circ pump TM? I have searched every term I can think of.....


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## Titan Plumbing (Oct 8, 2009)

Matt said:


> I can't find it. Do you remember the argument about the constantly running circ pump TM? I have searched every term I can think of.....


Google the damn thing...................LOL


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## Redwood (Sep 8, 2008)

Choctaw said:


> Google the damn thing...................LOL


Yea isn't he some kinda self professed Google ex-pert:laughing:


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## ILPlumber (Jun 17, 2008)

Google found it.......


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## SewerRatz (Apr 25, 2009)

There was an article in the P&M about tempering valves and recirc line design and a scalding incident that happened in a old folks home. I will see if I can find it and post it.


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## nhmaster3015 (Aug 5, 2008)

No way, there was an article in PM that wasn't about saving the freeking planet by going GREENE :furious:


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## Protech (Sep 22, 2008)

:laughing::laughing::laughing:



justin said:


> I think Red brass is 85 percent copper and 15 percent zinc. I am just cautious. *I have seen electrolysis on copper to brass.* The 15 percent is what gets me. I am on my phone typing this but I would be more than happy to post a pic of the pump application when I get back in town to comp. Thanks .


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## Redwood (Sep 8, 2008)

nhmaster3015 said:


> No way, there was an article in PM that wasn't about saving the freeking planet by going GREENE :furious:


Yea there was...

The one about becoming a Ben Franklin franchise...:laughing:


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## Plumbworker (Oct 23, 2008)

http://www.plumbingengineer.com/may_10/code.php
looks like the return is not done correctly and those dielectrics are a sediment hazard IMO


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## SewerRatz (Apr 25, 2009)

Plumbworker said:


> http://www.plumbingengineer.com/may_10/code.php
> looks like the return is not done correctly and those dielectrics are a sediment hazard IMO


Thats the article Thanks for the link. I thought it was P&M but I se it was the PE mag.


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## Redwood (Sep 8, 2008)

I like the amount of type that article spends pumping up the union vs non union...

Like that amounts to a hill of beans when your sitting in court getting sued...:laughing:


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## SewerRatz (Apr 25, 2009)

Redwood said:


> I like the amount of type that article spends pumping up the union vs non union...
> 
> Like that amounts to a hill of beans when your sitting in court getting sued...:laughing:


Yea that was a flaw of the article. It makes no difference if the guy was union or not.


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## justin (May 14, 2010)

Plumbworker said:


> http://www.plumbingengineer.com/may_10/code.php
> looks like the return is not done correctly and those dielectrics are a sediment hazard IMO


Tell me how you can tell it's done wrong. I'm pretty sure it's the valve not the install. I am our of town rill thursday but when I get back to comp I will post a pic of pump installation


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## justin (May 14, 2010)

Protech said:


> :laughing::laughing::laughing:


Don't understand. Ohhhhhhhh, yeah I understand now ... The highlighted.
It's a habit on the tmv's that I use dielectrics . No I don't put dielectrics on ballvalves or shower valves,and they are copper to brass ,but I will on tmv .They deserve unions , and I like dies cause they don't leak. But I have seen electrolysis on brass.wasn't yellow brass 60-40?


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## 1703 (Jul 21, 2009)

I have issues with the return piping as well IF it is piped through only the hot side of the valve. The return portion of the system will never work right if piped that way.

That may or may not be causing the issues you speak of.

Check the easy stuff first- are the check stops opening all the way? Are all the parts moving freely inside the valve? etc.


There a 3 or 4 different piping arrangements for leonard valves.

Attached is one for a high (above 25gpm) return.


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