Very confusing, cold water coming through hot water line?

[Skamin20]

A few real head scratchers. I installed water heater a year ago. Ever since the hot water isn't as hot. During the install I had the main water shut off and at this time didn't have the outlet hot water pipe hooked up to heater. I turned on the main water to the house to fill tank for a second, and water starting coming out of the hot water outlet line (backwards). I can't understand why or how that is possible.

2nd issue: Cold water seems like it is mixing with hot water in line somewhere. I have heater set at 135, it is coming out of the faucets and shower heads anywhere from 100-112. In my bathroom i have a shower and big tub. Tub has individual handles for hot and cold. Lots of times when i start shower the water is only 100 degrees, then when i open up the tub hot faucet it is 112 degrees, when i shut the tub faucet off, my shower then gets hotter. After 8-10 minutes it starts cooling off and i can repeat the tub hot faucet turn on and the shower will get hotter again. What could possibly going on, could i be siphoning cold water into hot somehow like what happened in the first paragraph.

 

[Sylvan]

Most installers do not know about molecule stratification where heat (hot) goes to cold (absence of heat)

To prevent stratification (and lawsuits) we install a heat sink (27" loop) on the CW supply in lieu of check valves.


Are you sure you connected the CW line to the inlet? Very common mistake.

 

[Sponsor]

 

[Reach4]

A few real head scratchers. I installed water heater a year ago. Ever since the hot water isn't as hot. During the install I had the main water shut off and at this time didn't have the outlet hot water pipe hooked up to heater. I turned on the main water to the house to fill tank for a second, and water starting coming out of the hot water outlet line (backwards). I can't understand why or how that is possible.

Sounds like a crossover. This can happen various ways. One is to have a Y combiner, with the supply faucets turned on and the ouput blocked.

 

[Bannerman]

Are both the incoming cold and outgoing hot plumbing connections located on the top of the WH? If so, there will be a dip tube that should be installed in the incoming cold connection, to deliver cold water to the bottom of the tank without mixing with the lower density hot water above.

The low temperature exiting the WH will normally suggest a broken or missing dip tube, but your reference to water exiting from the outlet almost immediately upon opening the cold fill valve, suggests either the hot and cold connections are reversed as Sylvan questioned, or the dip tube was incorrectly installed into the hot water outlet instead of the cold inlet.

If the cold water inlet is located on the side, near the bottom of the tank, with the hot outlet located on the top, no dip tube will be utilized.

 

[GReynolds929]

You have crossover happening somewhere in the system like @Reach4 suggests. In addition to a two handle faucet like a mop or utility sink with both handles open and the spout capped, single handle shower cartridges are another common failure point. Sometimes you can pinpoint by shutting off the water heater inlet valve, going to a faucet shutting off the cold stop, opening the faucet to hot, then go around listening for the faucet that sounds like water is running through it.

 

[Skamin20]

You have crossover happening somewhere in the system like @Reach4 suggests. In addition to a two handle faucet like a mop or utility sink with both handles open and the spout capped, single handle shower cartridges are another common failure point. Sometimes you can pinpoint by shutting off the water heater inlet valve, going to a faucet shutting off the cold stop, opening the faucet to hot, then go around listening for the faucet that sounds like water is running through it

thanks for the replies. So I just shut off the cw inlet to the water heater, i shut off the cold valve to a sink, opened the hot water faucet and cold to warm water was coming out. I then went over to the whirlpool tub (with 2 handles) and opened the hot water faucet and nothing but cold water came out. There shouldn't be anything coming out of the hot water faucets if i have the water heater inlet closed correct?

 

[John Gayewski]

Are your site your installed the water heater correctly? Are you sure you hooked the cold water inlet on the right of the water heater and the hot water outlet on the left? Sometimes piping seems like it should be one way but it's actually setup in a way that is not intuitive and it can be easy to hook things up backwards.

Do you have mixing valves under your sinks? Or electronic faucets?

 

[Skamin20]

Are your site your installed the water heater correctly? Are you sure you hooked the cold water inlet on the right of the water heater and the hot water outlet on the left? Sometimes piping seems like it should be one way but it's actually setup in a way that is not intuitive and it can be easy to hook things up backwards.

Do you have mixing valves under your sinks? Or electronic faucets?

definitely not a plumber but i took pics when i took the old water heater out and i have double checked and I have trace some lines

I don't have electronic faucets

 

[Bannerman]

You have crossover happening somewhere in the system like @Reach4 suggests.

While I agree, there could continue to be a crossover somewhere in the plumbing system, Skamin20 said:

During the install I had the main water shut off and at this time didn't have the outlet hot water pipe hooked up to heater. I turned on the main water to the house to fill tank for a second, and water starting coming out of the hot water outlet line (backwards).

By this, the only way any water could exit almost immediately from the Hot outlet on an empty tank, would be from either the Hot and Cold connections being reversed, or the result of the dip tube being installed in the Hot outlet nipple. In either situation, the Cold water will enter directly at the top of the tank, with the water from the bottom of the tank, being pushed up the dip tube and out from the open 'Outlet' nipple.

 

[Sylvan]

Do you have Moen faucets??

 

[Skamin20]

Do you have Moen faucets??

kohler

 

[Sylvan]

Moen had a problem with mixing