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Author:
Anonymous User
I have a problem with hot water coming out of the cold side of my faucet. I have read on here that it is most likely water rising into the cold side at the water heater because there is a broken check valve.
I have been an apprentice plumber in service for a year and I have never installed any with any of my journeyman, nor have I seen any.
What gives?
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Author:
HytechPlumber (LA)
Depending on the installation determines if a check valve is required or not. A standard water heater does not require a check valve. A heat trap with the piping should be installed if the hot water leaving the water heater travels upward and/or horizontal. Once a check valve is installed the hot water system becomes a closed system causing thermal expansion. Now a expansion tank is required. Check valves are mostly used when there is a hot water return line or pumps involved. GOOD LUCK
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Author:
e-plumber (NY)
I have never seen or installed a check valve on a typical, (cold in / hot out) HW heater installation unless there is a HW recirculation line or a tempering (mixing) valve installed at the water heater.
If the HW is rising into the CW piping you should only get luke warm water from the cold side and for a very short time, a few to several seconds the most.
What type of faucet is this happening in and how long does the water run hot from the cold side?
e-plumber
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Author:
hj (AZ)
Many modern heaters have "heat traps" built into the inlet and outlet which would stop the convection, assuming that is what is causing the problem. There are other things that can cause the symptoms so you have to check carefully before taking any action.
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Author:
Edward429451 (CO)
3/4" brass SWT check valves are common. Used to use them alot when installing water softeners less than 10 ft from the WH.
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Author:
rudythplbr45
There may be an open washing machine solenoid valve, allowing crossover between hot and cold; also, maybe a shower valve that is not shut off at the valve, but at the head or header.
Look for crossed over piping, (hot to cold, and vice versa).
I used to do that, occasionally; get turned around under the plbg being installed, and pipe a fixture with the water supplies crossed over.
Embarrassing, for sure.
Good Luck,
Rudy
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