hot water coming into cold water line

I manage the facilities for a 100 year old hotel turned into a school...in our big commercial kitchen, when you turn on the cold water in the morning at the sinks you get 30 seconds of very hot water coming out...thn the cold comes...anybody got any clever ideas on how to figure out where it is coming from...I already know I can hire a plumber who may spend hours tracking it (at $90 per hour)...I am looking for a do-it-yourself solution.
Many thanks for any help.
Mike
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snipped-for-privacy@oaklandsyda.org (mike) wrote in

It is coming from inside the pipe. It is the water that has been sitting in the pipe all night. Why it is so warm, how would we know? You are there, we are not. Just follow the pipe back and see where it runs up against a source of heat.
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mike wrote:

Is it a new problem? Do the cold water pipes run next to some heat source?
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If it's not as the other two posters suggested then....
I'd look for a cold water leak and "assume" that the pressurized hot water was "back filling" through the faucet?
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into a

the cold

very hot water

ideas on how

can hire a

hour)...I am

I don't think proximity of the hot/cold pipes would result in water as hot as you seem to indicate, but it's possible. Especially if they happen to be wrapped in the same insulation somewhere along the line.
Check around the plant equipment: water heater, boiler, etc., for valve arrangements that could tie hot/cold water together. If it's not proximity heating, which I don't think it is, the somewher along the line there must be someplace where valving or even a stupid plumbing mistake let the two cross somehow where there is a slow running mixing. What's the possibility that all the air-traps and/or tanks are waterlogged and during nonuse, heating of the water causes water th back up, and when it comes forward, comes out the cold water pipe? Try running the hot water first, then the cold water after. If the cold isn't hot then, it's pretty likely a backup around the heater/boiler, whatever you have.
Pop
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A very common cause of this is a single handle faucet which leaks internally between the hot and cold connections. Feeling of the supply pipes will detect this. A check valve or regulator in the cold water feed without an expansion tank at the heater will also do it. Don Young

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