# Hot water cross connection conundrum. . .



## UALocal1Plumber (May 13, 2009)

Edited


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## 1703 (Jul 21, 2009)

A few thoughts off the top of my head:

- tempering valve as you say
- moen faucets?
- mop sink faucet with shut off valve on spout?
- prerinse on 3-comp sink?


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## drtyhands (Aug 16, 2008)

no expansion tank.
leaking toilet pulling hot water down the cold line.


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## Pipe Rat (Apr 5, 2009)

I cant tell you how many times I have found a mopsink to be the problem. Usually you will find a hose and valve on the spout with the hot and cold stems left open or you'll find it hooked up to a soap/chemical dispensing system again with stems wide open. With no recent plumbing being done and an abrupt and building wide problem thats where I would start.


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## LEAD INGOT (Jul 15, 2009)

Piperat said:


> I cant tell you how many times I have found a mopsink to be the problem. Usually you will find a hose and valve on the spout with the hot and cold stems left open or you'll find it hooked up to a soap/chemical dispensing system again with stems wide open. With no recent plumbing being done and an abrupt and building wide problem thats where I would start.


 I agree with the mop sink faucet. Also one little trick is to see if they have a softner. If the venturi gets clogged it can cause a cross connection. That little pearl would saved me a crapload of headaches at a Mc Donalds about 5 years ago. Finally threw it into bypass and bam it was right as the mail.


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## user4 (Jun 12, 2008)

There is no such thing as a hot water heater, if the water was hot there would be no need to heat it.

I have seen Price Pfister pressure balancing cartridges leak hot into cold without leaking at the spout many times, the same with Moen. Piperat is nailed it with the mop sink, that is probably the most common one. The fact that the guy claims the temp is the same out of both sides leads me to believe that he is either insane, or there is something like a large tempering valve that is malfunctioning and causing the problem.


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## Bill (Jun 17, 2008)

Piperat said:


> I cant tell you how many times I have found a mopsink to be the problem. Usually you will find a hose and valve on the spout with the hot and cold stems left open or you'll find it hooked up to a soap/chemical dispensing system again with stems wide open. With no recent plumbing being done and an abrupt and building wide problem thats where I would start.


Thats right:thumbsup:
I had a similar problem and it was a pre wash sink with a hose on the faucet, both hot and cold water left open, the hose had a hand controlled valve to turn it on. Whenever the urinals were flushed the hot water fed back through the cold line


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## Pipe Rat (Apr 5, 2009)

KTS the hot water temp being the same on both sides is a classic symptom of the 'ol mopsink scenario. :yes:


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## UALocal1Plumber (May 13, 2009)

I just got through looking at the system. Super called in and said it couldn't wait for tomorrow. 

This is a facility with 4 different buildings. Steam and CW are brought to each of 3 buildings through underground casing from the boiler room in 1 building. They enter and exit from the foundation walls with gland packings/grommets that have 3/8" threaded studs drilled into the concrete, with beveled rubber washers sealing the penetration through a metal plate.

3" CW line coming into problem building is approx. 130 degrees F. All CW lines in building are same. Shut down DHW valve, drained HW riser, CW still coming out at 130.

Went down to mech. room where CW and steam are coming into building. . . noticed steam vapor and pooling coming through rotten grommets. Temp of pipe as it comes through is 130.

Went to main building, boiler room, took a look at steam and CW line leaving to go to problem building. Guess what? CW line is as cold as it gets. Major steam vapor exiting penetration, with water pooling into room.

Developed length of lines underground are about 150'. If the steam line has ruptured horribly enough, it would be "pre-heating" the DCW line to dangerously high temperatures. I told the super to sit on it tonight, he's shutting down steam to the problem building (offices not used at night), and running cold water through a high GPM faucet to try and draw some 60 degree water through. He'll check it all night, if water cools off, we know what the problem is. If not, we have a lot more exploring to do.

The lines are run under asphalt in an active driveway. Tearing up any of the pipe is going to become a major hardship for them. I'm almost inclined to recommend that they consider epoxy lining blown in from the boiler room. Anyone have any experience with that stuff? The Port Authority of NY and NY uses it all the time on standpipe lines. . . I have no personal experience with it, and don't know what the performance would be on steam.

Anyway, thanks for listening,
Keith


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## Pipe Rat (Apr 5, 2009)

Nevermind I don't think its the mopsink.:no:


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## Redwood (Sep 8, 2008)

I've relined poop pipe!
Somehow I don't think we are in the same league... :laughing:


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## Airgap (Dec 18, 2008)

Sounds like someone's going to be digging up some steam pipe. Has there been a drop in steam pressure? I don't know much about epoxy lining, but I doubt it would work on steam for long, if at all....


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## dankman (Nov 19, 2009)

Epoxy lining+steam=total fail

It's time to dig.


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## Pipe Rat (Apr 5, 2009)

One thing that causes me to question the "Steam" as being the culprit is the statement by the maintenance man that the hot and cold are the same temperature. Just thinking outloud here. Are the supply lines all individual runs from the supply building to each seperate building? Do they share a common chase? If a common chase I suppose a steam leak could in effect turn the chase into a heat exchanger but I wouldn't think you would have a constant temperature under heavy flow as in when you refilled the HW riser especially if the pipes are insulated. If indeed it is steam leak related maybe an infrared thermometer could pinpoint the hotspot outside. Please share your findings I love this kind of stuff.


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## Cal (Jun 17, 2008)

Reading this ,, I'm with Piperat . A matching temp would most likely NOT occur unless it's a cross connection . Sorry not more help ,,, but don't waste time & $ on things that are a low % possibility /

my .02


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## Bollinger plumber (Apr 3, 2009)

UALocal1Plumber said:


> I just got through looking at the system. Super called in and said it couldn't wait for tomorrow.
> 
> This is a facility with 4 different buildings. Steam and CW are brought to each of 3 buildings through underground casing from the boiler room in 1 building. They enter and exit from the foundation walls with gland packings/grommets that have 3/8" threaded studs drilled into the concrete, with beveled rubber washers sealing the penetration through a metal plate.
> 
> ...


Call Jerry at perma-liner Industries in Largo Fla. He can answer any quetions for you. Tell him Al Lozier from Missouri suggested youcall him. He is a good guy will be happy to answer any of your questions.
You can also call warren enterprises in Mass. I think his name is danny. Just google them both they both have websites.


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## UALocal1Plumber (May 13, 2009)

Will keep everyone posted as things develop. 

Keith


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## Pipe Rat (Apr 5, 2009)

Any updates?


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## UALocal1Plumber (May 13, 2009)

I walked the path with an infrared thermometer and we felt like we pinpointed the area of the leak. A circle on the asphalt about 16' round, with peak temperatures of 105 at the center, with receding temps as the radius spreads. I have a crew of 5 going there tomorrow to do a seek and destroy, they'll be doing a 6' x 6' square opening and going straight down to see what the condition of the pipe is. Most likely will be doing a beveled edge welded repair of straight pipe, possible with an elbow. 4" sch. 40, we'll cover it with a section of vaporlock waterproof insulation. I have a feeling that we'll end up changing the run eventually, for now we need to get a grip on what's going on with the general condition of the pipe. 

When we quoted the price to change the whole line, the building manager did one of those silent, "let me take in what you just told me for a few seconds", "I think I'm having a heart attack" faces. It was priceless. So we opted for a more manageable spot repair. 

I'll take pictures.

Take care
Keith


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