Hot water is coming from 2 cold water taps and one upstairs toilet, turns to cold after 15-20 seconds, it comes out very hot. Thought it might be Bleeding through faucets, so changed laundry tub and kitchen faucett. Still does it. The cold pipes seem to get hot from near the water tank. The dip tube would give the opposite effect? I am fairly handy, but am stumped. The hot water heater( Gas ) was replaced about a year ago, by the gas company. Any ideas?

Good morning Gordon, You are correct, the dip tube directs cold water to the bottom of the tank however the cold water supply line is always hot near the tank. This is caused by convection from the heat of the tank heating the copper pipe. I don't think the heater is at fault. Your problem is caused by a cross connection. Have you installed any new appliances lately? Are there any hot and cold valves or faucets left open that are tied together may be feeding each other. I can think of one. Your washer has hot and cold faucet supplies that are left in the open position. If the mixing valve in the washer were faulty that could be your cross connection. Shut the washer faucets off over night and in the morning check to see if that don't help. Let me know what you find. Cheers, Tom

Does all the hot cold water come from the pipe near the hot water heater? Was the vent or any of the pipes rerouted when the hot water heater was installed? Modern hot water heaters are well enough insulated that the heater itself should not be heating up its surroundings. If the insulation was insufficient, your gas bill should have gone up. The old hot water heater was gas too? If the problem seems to be the vent being too close to the cold water pipes, you may want to replace a single wall vent with a triple wall type B vent pipe. You may have to come back before Tom and I figure this out completely.

Gordon,  Labman gives very good advice but this time he's way off base.  (Sorry Lab! ) Feel the cold water supply on any operating water heater, electric or gas, and you will find the cold water pipe near the tank is warm if not hot to the touch.  Metal will convect heat and copper is a dandy conductor. Labman blames radiation and that just doesn't happen, there just isn't enough heat that radiates from the flue to heat the cold water to a temperature for it to run hot from a fixture. And unless you have  reconfigured the supply and hot water pipe on the heater recently You won't find your problem in the heater either.  Check your system for a cross connection between hot and cold,  starting with the washer.  Good luck  Tom

Thanks for your help it was narrowed down to the Price Pfister shower unit, they are sending a new cartridge and shaft from California n/c. Funny that a lot of people including plummers are not aware of this. Thanks again - this of course is making the full assumption that this solves the problem- hopefully you won't hear from me again Gord

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Originally Posted by speedball1

Good morning Gordon, You are correct, the dip tube directs cold water to the bottom of the tank however the cold water supply line is always hot near the tank. This is caused by convection from the heat of the tank heating the copper pipe. I don't think the heater is at fault. Your problem is caused by a cross connection. Have you installed any new appliances lately? Are there any hot and cold valves or faucets left open that are tied together may be feeding each other. I can think of one. Your washer has hot and cold faucet supplies that are left in the open position. If the mixing valve in the washer were faulty that could be your cross connection. Shut the washer faucets off over night and in the morning check to see if that don't help. Let me know what you find. Cheers, Tom

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I had reverse situation. Thanks for your advice, speedball 1! My washer has not mixed hot and cold properly for years and kitchen faucet has been very slow to bring hot for years. I turned off the hot hose to washer.. . Instant fix of kitchen hot delay! Now if I only had a new washer! And I don't mean the rubber seal in the ends of hoses, lol

We had a similar problem arise in our small apartment building when the new water heater was installed. The water coming out into the toilet was the same temp as the water in the water heater--130 degrees, or something. It turned out that there was a check valve that had been installed backwards, and at night, when no one was using the water, the water heater was heating every inch of water in the building.

They flipped the check valve, and the problem was solved.

It took a few months for us to notice the problem.

Hey Toots,

Thanks for the update. Was the check valve on a recirculating system? Cheers. Tom

I *think* it was. We have a single-pipe system, bcs the place was built in 1921, but I think there's a small recirculating loop only in the basement.

We've actually had this recur; I'm checking to see if it's the cartridge in my single-handle faucets in my apartment, but I'm not absolutely convinced that's it. Mostly because in the evening, when I hadn't used my shower for 14 hours, the water in the cold tap was cool. If my own shower cartridge was at fault, I would have expected to get warm water immediately from that very tap. No?

But in the morning, the water from the faucets was cool until *after* I flushed the toilet, then the water was hot.

I had this problem whenever my recirculating pump is running. It seems to cause enough + presuure on the hot side to push the hot water through my washing machine inlet valve. I can shut the supply at the washing machine and the problem is not happening. Hot also travels back up the cold supply line but not too much. I am buying a new inlet valve for the washing machine. I am now just researching if this valve is defective or will the new one allow the cross flow also. I think it will not and the repair will save me from the routine of shouting from my shower "close the water valve!"

Is there a check valve associated with the recirculating pump Octothorp? Just curious here... let me know, OK?

Thanks...

Mark

I have the same problem. Very warm water from upstairs cold faucets for 15-20 seconds, but on the main floor the kitchen, near the laundry is normal. Just replaced the water heater, same, if not worse. We run out of hot water in 8 minutes taking a shower now, where we had at least 12-13 from the last one. One shower rough in valve was not replaced upstairs, I just don't understand how so much hot could cross the valve to heat the cold water all the time (nothing is dripping or leaking as far as I can tell). I will check the temp of the toilet water.

Hi utatskier and welcome to the Plumbing pageat at AskMeHelpDesk.com. You piggybacked on an a 7 year old dead thread so I gave you one of your own. In the future, before you post, look in the upper left hand corner for the date.
I think convection might be the answer as to why hot is sneaking over to the cold side. But that's a minor concern. The water heater concerns me more, Gas or electric? There a number of things that would cause a loss of hot water.
1. You could have a faulty element if electric. **OR**
2. Could be a broken dip tube on either gas or electric.
There's two places to check. Let me know what you find. Good luck, Toim

I had the same problem - hot water coming out of cold water taps. I figured out that the cutoff/flow valve in one shower had been shutoff, but the mixer valve had been left open. That allowed hot water to enter the cold water side of the water system when cold water was turned on elsewhere in the house due to pressure drop. That is, when the cold water is turned on, the pressure in the cold water pipes drops lower than the pressure in the hot water pipes. If a mixing valve (in a tub, shower, or single handle faucet) is left open or is defective, hot water is then pushed by the higher pressure on that side of the system into the cold water distribution pipes. I imagine that this could also occur if the mixing valve on a washing machine is defective. Because the shower valve was in the lowest part of the house, the hot water (being lighter than the cold) rose into the cold water pipes upstairs, eventually displacing all of the cold water. Shutting off the mixer valve cured the problem - I just had to open the cold water taps to flush out the hot water.

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Hi Robstone and Welcome to The Plumbing Page. At AskMeHelpDesk.com. You're responding to a 8 year old dead thread Look in then upper left hand corner of the first post form the date before you post, Thanks,

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Thanks for that most informative Post. You have stated it well. Thanks, Tom