# Backflow and Check Valves



## rjordan392 (Feb 9, 2005)

Hello,
I installed a backflow valve about 8 feet away from the water heater cold water intake because I was getting backflow from the water heater and this flow was entering the takeoff for the water supply to my refrigertor. At least I think its backflow because I can feel warm copper tubing 12 running feet away from the water heater and my refrigerator takeoff is two feet away from that. But now I am getting a single thud sound everytime I shut down a cold water faucet unless I close it slowly.
So I installed a water hammer arrestor down stream from the backflow valve and still get the thud sound. My questions are:

Should I have used a check valve instead of a backflow valve? 
Should the water hammer arrestor be placed up stream from the backflow valve? All my cold water faucets are up stream from the backflow valve. Water pressure is about 65 - 75 lbs.


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## mdshunk (Mar 13, 2005)

By installing that backflow preventer where you did near the water heater, you effictively closed up lots of pipework that the water heater previously used as an "expansion tank". Adding an xtrol to the water heater may give back that cushion that you need to eliminate water hammer when faucets and appliances cycle.


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## Double-A (Jul 3, 2006)

mdshunk is right in that you may have an expansion problem and adding an expansion tank to the system is now required as you have created a 'closed' system.

The thud you're hearing is most likely that 'backflow' valve slamming shut. I think if its slamming like that, it fits my theory of what your original problem was, and probably still is.

I think you have a cross in your hot and cold water someplace. You're getting cold water into the hot water system from someplace other than the feed line to the water heater. Otherwise, this should never happen. 

The dynamic cold water pressure at the heater will always be higher than the down stream pipes from it from just friction loss, and would normally prevent backflow through the heater. 

However, with a crossover between the hot and the cold, you now have higher pressure downstream of the water heater to 'backfeed' water through the heater and into your cold water lines. 

Get a plumber out there and get this fixed. Hot water is not for drinking.


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## rjordan392 (Feb 9, 2005)

Mdshunk and Double-A,
Or I could just remove the flapper valve from the backflow valve and leave the water hammer arrestor in place and save myself a lot of trouble. Overhead and floor space for an expansion tank is insufficient. If I go with that solution, I would have to have it installed 8 to 12 feet away from the water heater. 
I went 35 years without the need for an expansion tank and I don't think I'll go that route.
I been using bottled spring water in my fridge as I never did like the taste of the water from it which was the reason I installed the backflow valve. It was only recently that I suspected it was backflow after I felt the copper tubing near the takeoff and it was too warm to think something was not right. I might consider removing the fridge cold water takeoff to a location further upstream.
I heard that newer hot water heaters have backflow devices installed in them. Is that true? Mine is a Bradford White and I believe it is over 6 years old. I wonder if its a defective unit. 
If there is a cross over in my piping, then its in the walls somewhere.


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## mdshunk (Mar 13, 2005)

rjordan392 said:


> If there is a cross over in my piping, then its in the walls somewhere.


Or a failing single hangle faucet.


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## rjordan392 (Feb 9, 2005)

mdshunk said:


> Or a failing single hangle faucet.


That's a good possibility as my single handle kitchen faucet does leak quite a bit when I lean on it. I'll rebuild it.


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## Double-A (Jul 3, 2006)

OK, older home, no recent changes... Heat rise. 

I think if you look at that pipe you originally said was hot, you'll see it rises from the water heater. Since heated water is less dense than unheated water, it rises. Its just rising up the pipes. You can put in a u-turn on the cold water side to create a thermal spihon break. This gives the warmer water someplace to rise up to, but its at the highest point now, and won't go down. Just make it go up and then bend gently 180 degrees and back down about a foot, then turn again and where it goes from there isn't important to stopping this problem.

If on the other hand you only notice this pipe get warm when water is running, you have a crossover problem.


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## rjordan392 (Feb 9, 2005)

Double-A,
On a idea mentioned by Mdshunk, I re-built the single handle kitchen faucet. The old assembly would leak badly if I put some hand pressure on it. There may have been cross over at that location. In any event, I removed the backflow valve which caused the secondary problem of a thud sound. I am going to put things on hold for a bit to see if the water quality improves on the fridge water output. I already detect improvement in water quality from the kitchen faucet.
Prior to the change, the water always tasted flat like there was no oxygen in it.
My cold water pipes are running across the joists, then down into the water heater. I would have to make changes not to my liking to implement your idea about the U turn. Besides as mentioned before, space is tight and limited as I have heating/ac return ducts and a bathroom exhaust duct and a laundry drier duct tee'ed in that area. 
Thanks to you and Mdshunk for sheding some light on my problem and it appears I am on the right track.


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## WesternBackflow (Apr 14, 2014)

It does sound like the BFP, interesting theories, what ever came of this?


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