# Cross over valve



## geofd (Feb 17, 2018)

I was on another forum and this term came up I have not heard
of this..... I do alot more commercial stuff this was used in a home
domestic water heater with a pump in a home


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## WashingtonPlung (Jul 25, 2016)

geofd said:


> I was on another forum and this term came up I have not heard
> of this..... I do alot more commercial stuff this was used in a home
> domestic water heater with a pump in a home


Maybe you should explain what this valve does. Becuase i'm sure some of us have heard it by another name. 

Is it a mixing valve?


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## chonkie (Jul 31, 2014)

Probably referring to recirc system with no dedicated return line, the little block that's installed at the farthest point from the w/h, usually a lav, and it allows the hot to use the cold line for return to w/h. Grundfos has one you install the pump on the w/h and add the block.


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## PLUMBER_BILL (Oct 23, 2009)

chonkie said:


> Probably referring to recirc system with no dedicated return line, the little block that's installed at the farthest point from the w/h, usually a lav, and it allows the hot to use the cold line for return to w/h. Grundfos has one you install the pump on the w/h and add the block.


Chonkie way back ... early 2015 this was a pretty big discussion.

Here is what I said then.Originally Posted by *Best Darn Sewer*  
_All this is news to me. I never knew the Grundfos comfort system bypass had a thermal control valve. Even when I've spoken with tech support in the past they just said its a simple check valve. Are y'all sure its thermally controlled? Being the timer on the unit controls the pump why would it be thermally controlled?_


*The timer on the pump is to turn it on lets say 6:45 A.M. and then turn if off lets say 9:39 A.M. Pump can be turned on and off according to life style. Control valve shuts off when hot water detected at faucet.*


__________________
*Bill Parr LMP*
*www.parrsplumbing.net*
For my alternate web site, click on ...
*A little of this and a little of that* 







     
*The Following 2 Users Say Thank You to PLUMBER_BILL For This Useful Post:* Best Darn Sewer (10-04-2015), chonkie (10-09-2015)


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## geofd (Feb 17, 2018)

geofd said:


> I was on another forum and this term came up I have not heard
> of this..... I do alot more commercial stuff this was used in a home
> domestic water heater with a pump in a home


I read that when there is no return for domestic he
there is a fitting that's installed under a lav (I don't know
how to post pics) when the pump on the water heater is on 
it turns part of the cw into a hot return/as soon as a fixture is
used it shuts down that valve and it goes back to it origanal state
I will get the name of the one I found and post it

check out ready temp.com


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## chonkie (Jul 31, 2014)

I remember that discussion. After taking one apart and testing it, we did conclude that it is not just a simple check valve and it actually closes off when the h2o reaches a certain temp. Don't know what the temp is but it happens.

Here's a pic of the block I'm talki ng about geoff.


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## geofd (Feb 17, 2018)

geofd said:


> I read that when there is no return for domestic he
> there is a fitting that's installed under a lav (I don't know
> how to post pics) when the pump on the water heater is on
> it turns part of the cw into a hot return/as soon as a fixture is
> ...


Thanks chonkie....

that was something else I was wondering thanks for all the info!!!!!


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## Debo22 (Feb 15, 2015)

chonkie said:


> I remember that discussion. After taking one apart and testing it, we did conclude that it is not just a simple check valve and it actually closes off when the h2o reaches a certain temp. Don't know what the temp is but it happens.
> 
> Here's a pic of the block I'm talki ng about geoff.


Grundfos comfort system, it's designed to shut off at about 105 degrees. I got a call a few years ago where the homeowners complaint was when she turned cold water on at kitchen sink it was hot for about 2 minutes. A new bypass valve solved that problem.


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## chonkie (Jul 31, 2014)

anytimehvac said:


> A crossover valve is basically a defective or faulty mixing valve that allows cold water into the hot water pipes and/or hot water into the cold water pipes. This type of mixing valve is usually found wherever a hot and cold pipe meets at a fixture in a central heating system.



Next post of yours needs to be an intro. And how is a valve that is designed to allow hot water into the cold side "basically a defective or faulty valve"?


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## MACPLUMB777 (Jun 18, 2008)

Default Why Post An Intro?
Quote:
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