Warm water coming out on cold side of faucets

[blackhawk]

When I turn on the cold side of my faucets in my house, I get cold water at the very first and then it turns warm for several several seconds until finally turning cold again. This just started happening a few months ago. It has to be something going on with my electric water heater allowing heat up into the cold water supply. The cold water supply to the heater is measuring about 80-82F a couple of feet from the inlet nipple using my infrared thermometer. The cold water pipe gradually measures cooler as you move further along toward my fixtures. It is above 70F for at least 5 or 6 feet. The water heater is 14 years old and I have not changed the thermostat setting which is at 120F. The temperature and quantity of hot water is normal when taking showers, filling large pots, etc. Even though I already had a flexible, non metallic hose between the cold water supply and the heater inlet, I added a heat trap loop. When I made that loop, I added a plastic lined (heat trap) nipple even though the heater had one built in. The heat trap did not help at all.

I read online that faucet cartridges can go bad and allow hot water to pass to the cold side. I don't think this is my problem because it happens on all my fixtures and it sounded like when this happens, the cold side of the faucet is hot all the time.

The only thing that I think could have happened is that the dip tube for the cold water inlet on my heater has corroded and broken off near the top of the tank. Anyone else have any ideas?

 

[jlwest]

All fixtures? Are your water lines in the attic?

 

[blackhawk]

All fixtures. Water lines are in my basement which stays room temperature.

 

[mkepke]

I would work backwards from each affected fixture towards your (cold) water main.

Isolate each fixture so you can eliminate it as the cause. I wouldn’t jump to the conclusion it’s the WH.

It’s possible you have something like a cracked/failing mixing valve on an appliance like a washer or a shower valve.

Do you have a mixing valve on your WH? Do you have an expansion tank on your WH?

Was any plumbing work done recently?

-Mark

 

[Tarhead]

That's normal for us. The first cold phase is caused from water in plumbing cooled by being in your walls and floors. It gets warm from water in plumbing buried underground. It's hot, the ground heats up. It'll be reversed in the winter when the ground cools down.

 

[blackhawk]

Mark - No mixing valve or expansion tank on WH. No plumbing work done in the last 10 years. All the lines are cool at the fixtures. The only place where the cold water line is warm is at the WH. The cold supply pipe, cools down the farther you move away from the WH.

 

[Oka]

These would be low possibility but ......

If you were getting back flow from the WH then a check valve added to the inlet cols side would solve for that,

Another random possibility is the internal mixing ball in the single lever has gotten decayed on the part or the seal and ho water is venturi'ing in when turning on the water.......

Regardless of this a 14 yr old water heater is due for a change it is at the end of its life cycle

 

[mkepke]

Hmm

That warmth on the cold supply line may be normal conduction and/or because the hot water in the tank is expanding back into the cold water line. The expansion is what heat trap valves and expansion tanks are intended to control.

This may just be normal behavior for your set up, the trap valve may have failed or your tank may be building more pressure than normal. (Would you know if the amount of pipe heating you see is normal for your setup?)

Are you seeing any dripping etc from the WH pressure relief valve? (Have you exercised the pressure relief valve recently to ensure its functional?)

-Mark

 

[Henry W]

Not sure I understand the potential backflow issue at the water heater - because that is a supply line for the water heater. What does it matter that it pre-warms?

Of course if the split in the supply line (source line T-ed into a line for water heater and one line to CW supply ) is very close to the water heater (not the case in my house) then back flow and heat leakage back up the supply line would be an issue.

 

[jlwest]

Hmm

That warmth on the cold supply line may be normal conduction and/or because the hot water in the tank is expanding back into the cold water line. The expansion is what heat trap valves and expansion tanks are intended to control.

This may just be normal behavior for your set up, the trap valve may have failed or your tank may be building more pressure than normal. (Would you know if the amount of pipe heating you see is normal for your setup?)

Are you seeing any dripping etc from the WH pressure relief valve? (Have you exercised the pressure relief valve recently to ensure its functional?)

-Mark

Be careful with exercising a old relief valve. It can cause other issues.

 

[blackhawk]

Oka - From what I have read, if I put in a true check valve, I also have to add an expansion tank. Lowe's sells a dielectric nipple which is exactly what I used, except it has the added feature of a rubber flapper. It says that it can be installed in either direction, so it would not prevent flow, so those should not need an expansion tank. The rubber flapper just prevents the heat from escaping the WH. I'm just worried how long that flapper would last before it falls out into the tank.

Mark - This is not normal as the problem just started a few months ago. As you mentioned, my tank could have had a built in flapper valve and it has failed. Something changed. It may be worth trying the Lowe's flapper nipple

Henry - The heating up of the cold water isn't a huge issue. It is just costing me some extra money. 1) I am losing heat from the water heater so my electricity usage is higher. 2) Whenever I need a some cold water, I have to let the water run 15-20 seconds to cool off so I am wasting water which I pay for. The water usage may even out when it is winter because I won't have to wait as long for hot water when I wash my hands.

 

[Alan in Little Washington]

Was your house plumbed for hot recirc so you would hopefully not need to run the hot faucets, showers, tubs that are far from the water heater to purge cooled hot water from the line (and needlessly waste water and time waiting for hot to arrive at distant spigots?

My house initially had a poor man's recirc system consisting of a recirc pump w/timer in the hot water line, a check valve, and a pilot valve at the farthest point from the hot water heater. The pilot valve connected the hot to the cold- it used the cold line as a return for the cooler hot water. This was to ensure hot water would be available right away. It never really worked right, however. I still had to let the hot run for a bit before using the bath or shower and also cold water always came out warm (not nice when brushing my teeth). A failure or improper operation of the check valve or pilot valve in this system can cause your problem.

I eventually removed the pilot valve and capped the cold water line. Then I connected the hot to a new hot return line that runs back to the water heater. It all works great (as long as there are no power outages affecting the timer. While running the new return/recirc line in the crawl space I also insulated all water lines.

 

[Tarhead]

Mark - No mixing valve or expansion tank on WH. No plumbing work done in the last 10 years. All the lines are cool at the fixtures. The only place where the cold water line is warm is at the WH. The cold supply pipe, cools down the farther you move away from the WH.

That's conduction from the water heater through the valve going into the pipe. Put some pool noodle type insulation on it and don't worry.