Sudden Reversal of Hot and Cold Water

[PlumbingSense]

What would cause the hot and cold water of the kitchen faucet to suddenly reverse, when cold water is being used from another faucet?

By reversal, I mean: when the single lever kitchen faucet is all the way to the cold position, hot water would come out, and when it is all the way to the hot position, cold water would come out. This strange behavior would happen when cold water is being used from another faucet in a small bathroom.

When cold water is not being used in another faucet, the kitchen faucet would function normally, although it takes quite a bit longer for warm water to come out (compared with the old kitchen faucet). The new single lever kitchen faucet is recently installed. It has the long pull-out spout. I think it is installed properly. I have tested it. When the cold water cut-off valve is shut off, no water will come out of the kitchen faucet at the cold position. When hot water cut-off valve is shut off, no water will come out of the kitchen faucet at the hot position.

(The cold water usage in the small bathroom can also cause the strange reversal in faucets other than the main kitchen faucet, but it is more noticeable with the main kitchen faucet. And besides the small bathroom faucet, another faucet in the kitchen could do the same thing to the main kitchen faucet. The faucets in our house seem to have rankings as to which one would dominate and cause the reversal in others.)

We are in the process of remodeling the main bath room. Pressure Balancing valve faucets are being installed in separate shower and bath tub in the main bathroom. The pressure balancing valves are hooked up to hot and cold water lines already, although they are not functional yet. Tile work is being done now. Could these pressure balancing valves do strange things to the rest of the plumbing in our house? Water pressure is not high (but not too low) in this old house. Even though we have copper plumbing under the house, the main water line is still old. We will replace the main water line soon. Will that solve the problem? But what is causing the erratic hot and cold water behavior in the first place? (And perhaps we always had the reversal problem but didn't notice it before, until now that we are using the small bathroom more?)

Please help.

 

[Cass]

I am going to guess here that someone during the remodeling process has created a cross connection somewhere unless you had this problem before the work started.

 

[Sponsor]

 

[Jimbo]

This poster's problem has been identified and solved on another forum: The shower valves put in are Delta R10000's, and they were installed and left with the blank plug installed.

 

[PlumbingSense]

Mystery solved ... Crossover? Where?

You are right about your guess! And you are also right that the problem was identified in another forum in theory, based on this part of the original description:

"...We are in the process of remodeling the main bath room. Pressure Balancing valve faucets are being installed in separate shower and bath tub in the main bathroom. The pressure balancing valves are hooked up to hot and cold water lines already, although they are not functional yet. Tile work is being done now...."

One of the new main bath room faucets is indeed a Delta MultiChoice Universal. The rough valve body was installed and hooked up to hot and cold water with a blank plug but the cartridge was not installed yet. This Delta faucet does come with the cartridge in the box but the cartridge is not pre-installed inside the main valve body. The main valve body comes with the blank plug. And I guess the contractor wanted to wait until after the tile work before installing the Delta cartridge together with all the trims.

Now, let's see if we can confirm that in real practice with our situation.

So, I asked the contractor to install the cartridge into the Delta rough valve body to see if any crossover will be eliminated and the strange behaviors of our other faucets will go away.

But the contractor suspected more the new kitchen faucet being defective and causing the crossover. Therefore he was quite skeptical about our idea with the Delta cartridge (because the main bathroom is quite far from the kitchen?), but he was willing to try anyway.

Viola ..... with the Delta cartridge installed, all the strange behaviors of our faucets go away instantly just like magic! The new kitchen faucet gets warm and hot water when it is supposed to but gets it much faster. And it gets only cold but not any warm or hot water at the cold position at all (not even when lots of cold water is being used somewhere else). No more crossover.

So, it is confirmed in the real world.

Mistakenly thinking that it might be defective, we almost took down the new kitchen faucet to exchange for another one. Now we won't. And we can also close all the wall and finish the tile work in the main bathroom with the peace of mind, knowing that there is no cross connection anywhere else in the remodeling (behind the walls).

Thanks!