Lukewarm cold water...help me solve the mystery!

[elle]

As the title indicates, our cold water from ALL faucets starts out cold and within 20-30 seconds turns luke warm. This phenomenon started a month or so ago after a visit from a plumber. The plumber did the following:
1) Replaced a kitchen faucet with a Moen single handle
2) Replaced our washing machine supply hoses (hot and cold)
3) Took a "look" at our water heater-- I wasn't down there when he did, but I heard him messing around with something and was in the utility room for quite some time.

I pretty much know NOTHING about plumbing, so please forgive me in advanced.

To trouble shoot if this problem is in fact due to the kitchen faucet, I turned off the hot and cold water supplies under the sink and went to bathroom sink and turned on the cold water. As usual the water started cold and then after 20 seconds turns luke warm.

Next, I shut off the water supply to the washer and repeated the test in another faucet. Same results.

I felt the supply lines near the water heater. The cold supply line into the water heater feels neutral- not hold or cold. The hot supply feels warm.

Is there something else I can do to pinpoint the cause of this problem?

Moen is sending me a replacement cartridge for the kitchen faucet-- but since I turned the supply off at that faucet and the problem still occurred, wouldn't that mean this cross over is NOT being caused by the Moen kitchen faucet?

Any help would be GREATLY appreciated here!

 

[Reach4]

You don't have a hot water recirculation system, right? Presuming no recirc system, suppose you use no water for a good while. All pipes will be at about room temperature. Then you turn on the cold from the tub or some other path. The hot water pipes coming into the fixures should all feel room temperature except the one with the leak. And the cold out of the mixer at the WH should stay room temperature.

If the cold pipe at the WH fixture gets warm/hot with only cold being drawn, that mixing valve is the leak.

 

[Sponsor]

 

[elle]

You don't have a hot water recirculation system, right? Presuming no recirc system, suppose you use no water for a good while. All pipes will be at about room temperature. Then you turn on the cold from the tub or some other path. The hot water pipes coming into the fixures should all feel room temperature except the one with the leak. And the cold out of the mixer at the WH should stay room temperature.

If the cold pipe at the WH fixture gets warm/hot with only cold being drawn, that mixing valve is the leak.

I don't believe I have a recirc system-- (again I know NOTHING about plumbing, so I could very well be wrong). I will double check the lines at the WH while running cold water tonight.

I did notice that while doing laundry on a COLD cycle, the cold water supply hose felt slightly warm. But again, the problem persisted in other faucets even after closing both supply lines to the washer-- so would that indicate the problem is NOT from the washer?

Is there something the plumber could have adjusted in the WH to cause this issue?

 

[elle]

It doesn't look like my WH has a mixing valve in it and the cold water pipe remains room temperature. Any other ideas on how to find the source of the cross over?

 

[CountryBumkin]

Do you have other single lever faucets in the house?

 

[Reach4]

I did notice that while doing laundry on a COLD cycle, the cold water supply hose felt slightly warm. But again, the problem persisted in other faucets even after closing both supply lines to the washer-- so would that indicate the problem is NOT from the washer?

I think that means that the washer is not the problem.

Is there something the plumber could have adjusted in the WH to cause this issue?

No. He could have installed something on top of the WH however.

It doesn't look like my WH has a mixing valve in it and the cold water pipe remains room temperature. Any other ideas on how to find the source of the cross over?

Feel all of the supply lines of the fixtures that are not turned on and have not recently been on. They should all feel room temperature if they are not guilty of passing water while turned off.

 

[elle]

Do you have other single lever faucets in the house?

Yes, I have 3 bathroom sinks, 3 showers and the kitchen sink. I just thought it was odd it only happened once the kitchen faucet was replaced-- but the problem continued in other faucets after shutting the water supply off to the kitchen sink.

 

[elle]

I think that means that the washer is not the problem.


No. He could have installed something on top of the WH however.

Feel all of the supply lines of the fixtures that are not turned on and have not recently been on. They should all feel room temperature if they are not guilty of passing water while turned off.

Thanks for your help! I keep trying to feel everything and it all feels room temperature, unless they are on. For the washer, the cold supply line only felt warm while I was running the washing machine and water was filling the basin.

I guess my question is-- if the problem persists even when I shut off the supply lines to either the washing machine and/or the kitchen sink-- does that mean it is NOT those faucets causing the issue? Or could the issue still be one of those faucets, even when the water supplies are closed to them? make sense?

Is there a way to test to see if its a shower-- since you technically can't feel those water lines?

 

[Reach4]

I guess my question is-- if the problem persists even when I shut off the supply lines to either the washing machine and/or the kitchen sink-- does that mean it is NOT those faucets causing the issue?

Yes.

Is there a way to test to see if its a shower-- since you technically can't feel those water lines?

Often there is an access panel on the other side of the wall. You might have to remove some shelves to access it. But if that is not a closet on the other side of the wall, there is probably no access panel.

You might be able to pull off the dress plate from the shower side.

 

[hj]

The only time we get "cold water" is in the wintertime. The rest of the time it is always "warm" because the pipes in the ground are heating up. or the pipes are in the attic and get hot from that. The "initial cold water" is because the water in the pipes in the wall are cooling down to room temperature.

 

[Jadnashua]

Between summer and winter here, my incoming cold water's temperature can vary over 40-degrees, but it takes time to change with the seasons...not immediately after some plumbing work was done. But, if your 'cold' water is the same temp as what's coming in...that's the best you'll do in this season. As was said...the warming up of the 'cold' water is more likely the result of flushing out the water that is in the pipe inside the house and replacing it with that from outside, where it is not being cooled by the a/c.