mixing hot and cold water


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Old 05-07-06, 03:30 PM
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mixing hot and cold water

I had my house repiped a week ago. Part of the agreement was to install a cheap shower type valve on the patio wall and run hot as well as cold water to it, to allow me to mix warm water to wash the dogs with.

When they started the foreman had not been made aware of this add-on. He ran hot and cold taps with normal, inexpensive spigots (?) however indicated he had no valve, and he could not connect the two to form one hose connection because that might allow the hot and cold taps to mix. He checked with his companies owner who confirmed: no go.

I've since checked with a few others and am curious: is there any reason, beyond perhaps some energy expense, not to mix a hot and a cold tap? I'm considering connecting them with a Y connector.
 
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Old 05-07-06, 03:56 PM
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Just putting a wye AFTER the taps is no different than any type of shower valve or other faucet where hot and cold are mixed. The path of least resistance for both hot and cold water is out the tap, so crossover is not a problem. HOWEVER, if you put any kind of shutoff AFTER the two taps, including a nozzle on the end of a hose, now you have a situation where crossover will occur. Cold water will flow back towards the WH.

Putting any wye connection ahead of the taps is of course out of the question, for the same reason.
 
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Old 05-07-06, 05:31 PM
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Also, put backflow preventers on each one prior to installing the y, so you won't have the problem of cross flow.
 
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Old 05-07-06, 05:43 PM
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ok, thanks for the info. but Why is it bad to have water from one tap in the pipes of the other? Will it cause a corrosive problem? Or just waste energy? If the later, then I'm willing to waste the energy for the once a month 15 min this task will take.

Chandler : I asked about one way anti siphon units but the hardware store was unfamiliar with them.

This raises the question: does a shower valve or kitchen sink have some form of one way control? I replaced the sink fixture when repiping ( wall mounted, one valve for hot and for cold, mixes in the faucet ) and could not see any form of control... ?
 
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Old 05-07-06, 07:31 PM
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The backflow preventers look just like spigot extensions that screw on to the spigots themselves, then the hose attaches to it. Someone wasn't looking. The only reason I suggested it was that you would be opening the water to the atmosphere, rather than to a more controlled situation such as in a shower or sink. You just don't want any contaminants backflowing into your well, or to the water supply. It is not mandatory, and you can get by with a y on the two valves.
 
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Old 05-07-06, 09:04 PM
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Ask for a hose bibb vacuum breaker, not a backflow preventer.

While a vacuum breaker does stop backflow in certain instances the term backflow preventer applies to a much more complicated (and expensive) piece of equipment.

The hose bibb vacuum breaker is built-in to many frost-proof hose bibbs and a separate add-on unit is not very expensive.

http://edis.ifas.ufl.edu/AE079
 
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Old 05-08-06, 06:11 PM
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Sorry for the misnomer. Furd's right in the name, and it is a simple add on to the bib.
 
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Old 05-10-06, 05:25 PM
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Would the attachment in the photo linked to below be what you both were referencing?

http://www.paulathomas.com/PICS/rear...20(Medium).jpg

If so then the crew that repiped my house put them on all hose bibs. I sort of figured it was code ( I can remember multiple times 15-20 years ago when the water main would break that my water meter would run backwards sucking air in, thus occasionally giving me a negative water bill )
 
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Old 05-10-06, 06:10 PM
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You got it!
 
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Old 05-11-06, 07:36 AM
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Thanks to you both for clearing that up
 
 

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