# Mixing Valve under the lavatory



## srloren (Nov 19, 2014)

A new friend has a tankless water heater in his new home...built a couple of years ago in So Cal. It is a 5 Bedroom 2 story and in the master Bath, the farthest from the water heater which is in the Garage, he has a mixing valve on one of the 2 lavatories installed. I am not sure why this valve is installed? there are three 1/2" lines coming up through the bottom of the cabinet to the valve and it has a handle that removes to set the temperature. Why does he want to control the temp only on one lavatory or could that temp controlled line go back down under the floor and feed the shower and other lavatory? Any ideas?
Having not been involved actively in the trade since 1999, I am perplexed.


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## Bayside500 (May 16, 2009)

perhaps to feed a bidet or big jacuzzi type tub with tempered water ?


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## srloren (Nov 19, 2014)

Bayside500 said:


> perhaps to feed a bidet or big jacuzzi type tub with tempered water ?


That could be it... makes sense because they do have that type of tub. Thanks much.


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## GREENPLUM (Jul 27, 2008)

Pics please


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## Texan (Feb 21, 2015)

Here in Austin tempering valves are required for two handle tub valves. This is so a kid cant yank on the wrong handle and burn himself or worse. Sometimes we put them under a lav like you described, but more often behind an access panel in the mb closet.


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## rjbphd (Feb 5, 2010)

Texan said:


> Here in Austin tempering valves are required for two handle tub valves. This is so a kid cant yank on the wrong handle and burn himself or worse. Sometimes we put them under a lav like you described, but more often behind an access panel in the mb closet.


All that trouble installing a device that will sticks from time to time.. yank the 2 handles faucet out and install with a MOENTROLA and be a Texas sized hero..


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## Texan (Feb 21, 2015)

Ha! Ya we could slap that positemp right to the deck. That would be awesome!  I have seen it a few times on the wall by a corner tub. It takes like twenty minutes to fill that baby up.


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## All Pro (Nov 15, 2013)

So he can set temp to stop condensation from dripping off the toilet


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## All Pro (Nov 15, 2013)

I've seen them installed for that reason but not the tub


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## rjbphd (Feb 5, 2010)

Texan said:


> Ha! Ya we could slap that positemp right to the deck. That would be awesome!  I have seen it a few times on the wall by a corner tub. It takes like twenty minutes to fill that baby up.


With MOENTROL, u'll fill the tub faster as its have volume than the pos positemp..


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## sparky (Jan 8, 2014)

only things in texas are queers and steers and i dont see no horns on your head,no just kidding,just kidding,sorry mods for that one but had to post that,i agree,you need to trace the line down to see what it is actually feeding before yanking faucets out and being a texas sized hero


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## Texan (Feb 21, 2015)

Well its Austin so I cant really say your wrong. Whats the water temp got to be to need a tempering valves on the toilets. I've never seen that. Must be cold.


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## Plumbbum0203 (Dec 14, 2011)

Are you sure it's not a recirc line from water heater? That's what it sounds like to me.


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## paultheplumber1 (May 1, 2014)

I'm thinking it's for the tub as well. I've posted before on here that I was required to add a mixer to a tub filler because it had a hand held. And that makes it fall under a shower in the code vs just a tub fill.


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## plumbdrum (Nov 30, 2013)

paultheplumber1 said:


> I'm thinking it's for the tub as well. I've posted before on here that I was required to add a mixer to a tub filler because it had a hand held. And that makes it fall under a shower in the code vs just a tub fill.



I hate this code and do not agree with it, but ya can't fight city hall and unfortunately I have to enforce this one.


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## srloren (Nov 19, 2014)

Plumbbum0203 said:


> Are you sure it's not a recirc line from water heater? That's what it sounds like to me.


I am going back to take a photo later today. Does it make sense to recirculate from a tankless heater. They do not have a tank of hot water. I am not up to snuff on Tankless so help me out here.


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## Plumbbum0203 (Dec 14, 2011)

srloren said:


> I am going back to take a photo later today. Does it make sense to recirculate from a tankless heater. They do not have a tank of hot water. I am not up to snuff on Tankless so help me out here.



Yes I have seen recirc on a tankless. I'm not a expert there either.


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## Carcharodon (May 5, 2013)

srloren said:


> I am going back to take a photo later today. Does it make sense to recirculate from a tankless heater. They do not have a tank of hot water. I am not up to snuff on Tankless so help me out here.


Yea, you can have them on sone units, not the biggest fan of them on tankless heaters. An aquastat should be installed with them in my opinion.


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## paultheplumber1 (May 1, 2014)

If the hot water source is more than 50' away from the fixture it is required to have a recirculating line. That's the code here in RI anyway.


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## srloren (Nov 19, 2014)

paultheplumber1 said:


> If the hot water source is more than 50' away from the fixture it is required to have a recirculating line. That's the code here in RI anyway.


Does that go for a tankless heater also. I don't see how you would use a recirculating pump on a tankless. It seems to me that the tankless would be fired up continually (not energy efficient at all) because as the water returned to the tankless it would be cooler from heat loss. I have attached a photo of the mixing valve. I agree with the poster who said it would probably go to the shower and tub and other lavatory. The mixing valve is installed at the farthest fixture from the heater, where you would expect the return line to be, approximately 40 feet away.

http://www.plumbingzone.com/members/srloren-21104/albums/


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## paultheplumber1 (May 1, 2014)

Yup includes tankless. Some of the navian and rinnais that we put in has a built in recirculating line. Some of them are recirculating ready and the pump gets wired directly to the controll inside the heater.


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## srloren (Nov 19, 2014)

paultheplumber1 said:


> Yup includes tankless. Some of the navian and rinnais that we put in has a built in recirculating line. Some of them are recirculating ready and the pump gets wired directly to the controll inside the heater.


So they recirc on demand...correct. Then the heater goes off until the next fixture calls for hot water. Gas is used every time a hot faucet is turned on. 
My friends unit takes 2 minutes and 25 seconds to reach the lavatory that is furthest from the tankless.


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## Texan (Feb 21, 2015)

Usually they just have timer settings and an aquastat that , will turn it off when the loop is hot. Navian noritz and rannai all do built in pumps but you can do it with an 005 taco or better. Cant the op just run the water at the tub and see if it gets hot to know for sure?


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## srloren (Nov 19, 2014)

Texan said:


> Usually they just have timer settings and an aquastat that , will turn it off when the loop is hot. Navian noritz and rannai all do built in pumps but you can do it with an 005 taco or better. Cant the op just run the water at the tub and see if it gets hot to know for sure?


Texan, I will check to see how long it takes for the tub to get hot and check the temperature of the water while I am at it. You are right, that will tell the story. Thanks for your suggestion.


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## Texan (Feb 21, 2015)

Ok no problem.


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## themavinator (Apr 15, 2009)

I say its for the tub. I just put one in the other day.


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