Please help!! Several months ago I noticed that when turning any water faucet on or flushing the toilets, then turning the water back off, I continue to hear water running from the main water line/valve in my garage. As I began investigating this, I found that hot(heated) water is coming back out of the cold water inlet valve of the water heater tank. I called a plumber and he had me check and few things to see if the water lines were crossed but no. The home inspector checked this for me and I have also had a plumber come out. Both thought I was crazy, but did indeed find the problem as I described. If I flush the toilet it initially fills with hot water. The washing machine turned to cold wash/rinse and the hot water tap closed off still initially fills with hot water and then turns tepid but never cool or cold. You can feel the cold water inlet line on the water heater tank turns hot as the hot water is drawn back out of it when any water is turn on. The plumber thought it was the dip tube in the AO Smith 50 gal hot water heater and replaced it earlier this week. That did not fix the problem. Does anyone have any ideas or knowledge. Would a pressure problem create this problem?

Yup, a weird problem.

You only have one source of water pressure - the main line (cold) into your house. Once past your pressure regulator valve, this line splits - one part going to supply all the cold side faucets and the other being the cold inlet for your water heater.

Since this is your only source of water pressure, there is no way to have any pressure that is strong enough to cause a 'back pressure' to push hot water out of the WH and into the cold water supply line. In simple terms, if you looped your hot water supply out of the water heater and teed it directly into the cold supply, the result would be .... nothing. With only one source of water pressure nothing inside your house and plumbing system can make it back-feed.

So, I would look towards your main water supply as it sounds like you have some form of back-flow issue. If you are on city water, there is supposed to be a back-flow fixture as a part of the system that supplies water to your house. This is to prevent any contaminants that may be in your houses system from entering the public water supply. It sounds like this has failed and if so, it's time to call your water department and tell them what is going on.

Note: If you are on a well, then a check of your pumping system and pressure tank is needed - a damaged membrane in your pressure tank or a failing one-way valve could be the problem.

Other than the above, you can get hot water in your cold water system if you have a damaged or maladjusted fixture - usually the shower valve. Some of the anti-scald shower valves can malfunction, causing hot water to enter the cold water line. However, it is unlikely that the hot would travel all the way back to the cold water supply at the water heater so this is probably not your problem.

As an aside - when municipal water suppliers started installing anti-backflow valves several years ago, there became a greater need for a small expansion chamber attached to the water heater. This was because as the water heated, it expanded and had nowhere to go, often overpowering the pop-off safety valve and causing small amounts of water to escape.

What you've got is called (IIRC) a "cross connection".

It's caused by some plumbing fixture in your house causing cold water to get into the hot water supply piping, or vice versa.

One of the most common causes of a cross connection is using a "Y" mixing hose, like this:

http://ecx.images-amazon.com/i...uL._SL500_AA300_.jpg

on a garden hose. That's because people will use a spray gun or nozzle at the other end of the hose, and shut off the water flow by simply releasing the trigger on the gun or closing the spray nozzle. That shuts off the water flow, but still leaves the cross connection. So, if someone turns on the outdoor cold water spigot, it might be easier for hot water to flow through that "Y" mixing to the hydrant than for cold water to flow to it via another route. The result will be hot water coming out of a cold water outdoor hydrant.

Check your shower heads as well. Many shower heads have built in shut-off valves that allow a person to shut off the water temporarily while they lather up. The problem is that if they're not thinking, and they shut the water off at the shower head, but leave the shower valve open, there's a cross connection at the shower valve. Hot water can then flow through that shower valve into the cold water supply piping, and vice versa.

If this is a recent problem, and you're recently replaced any two handle faucets in your house with a single lever faucet, then I'd suspect that faucet. Maybe feel the faucet while hot water is running out a cold water spout (or cold water running out a hot water spout) in any other faucet in your house. See if the single lever faucet gets either hot or cold to the touch.

All good suggestions.
You need to go back and add where, at least the state you life in.
Is this a brand new house?
Reasons I'm making these suggestions is I used to live in SC, when my hot water heater stoped working the cold water line was putting out hot water and the cold was putting out hot.
Reason being was the town water lines were only about 12" under the street, so any water coming in was already hot.
The water heater was in an house with A/C so it was cold.
A new house may have had the hot and cold lines ran to close together so there could be some heat transfure.

Far more likly there's just a faucet or shower control valve causing the heat transfure, but some other things to concider.

The house is 9 years old, sat vacant for several months before I purchased and moved in Feb 1 2012.
Southern Utah town and water lines are not buried deep. I replaced both toilet tank flush contraptions a week after I moved in because they were not shutting off. That is when I found the hot water coming into the toilet tanks - very hot heated water in February. This hot water is not because it is warm outside. I put my hand on the cold water inlet valve to the hot water tank and the line is cold when the tank is filling. When I use any source of water and it is hot for several minutes I checked and put my hand on the cold water inlet to the tank and it is hot. Hot water is coming back out the cold water inlet into the cold water main line. I shut that water source off, water is filling the hot water tank back up to replace the water that was used. I replaced the valve cartridge in my shower (which was dripping slightly) yesterday, that did not correct the problem. I'm not using any "Y" mixing hoses. I don't have a recirculating pump unless it is hidden. All the faucets in my house (7 total) are single lever Pfister. Monday I will beging changing everyone of those.
What is a "check valve" and where is it/they located in the plumbing configurateion? Would a faulty pressure regulator cause this? Mine has alot of corrosion/deposits on it as if it has leaked at one point.

So, are you on a well or a municipal water system?

Before you go replacing all your faucets (and spending all the money with that project) just turn off the supply valves to each faucet and observe the results. Even if you have to turn one or two faucets at a time off for a couple of days it will be a better method of troubleshooting - unless you want to replace those faucets anyway.

There are some basic physics here that cannot be ignored. Let's assume that you are on a public water supply system. At the meter, there is 100 psi of pressure (just a number to work with as this can vary widely). The main line into the house will have this same 100 psi until it hits your pressure regulator, where it's reduced to around 50 psi. Somewhere past the regulator, the line splits - one becomes the cold water supply for the entire house and the other becomes the cold inlet to the water heater. The hot exit line from the WH is now the only main hot line that in turn branches out to supply all the hot water to faucets.

A malfunctioning faucet, 'Y' connector or other crossovers will cause weird temperature fluctuations both to the bad fixture and possibly to other fixtures nearby. If no other water source is used, then the hot to cold problem will be within the faulty fixture only. However, if there is a crossover point, all it takes is a cold line being used (like a toilet tank filling) to draw the hot water from the crossover, through the connecting cold water lines and into the fixture. This is what happens for things like the hot water in your toilet tank.

The hot water in your cold supply line to the water heater is a different story though. Again, physics rule here. You have 50 psi supplying cold water to your water heater. Your entire house has no more than 50 psi anywhere in it. It is not possible for 50 psi of hot water in your water heater to push against an equal 50 psi of cold water supply without another element causing the problem. Those elements could be:

1. Your water heater is getting too hot and the pressure relief valve is stuck closed. This would affect things when no water was being used. the water in the water heater will overheat and expand and will need somewhere to go. Normally it would pop the pressure relief valve but if that is stuck then the hot water would be forced out of the tank and into the cold water supply line. This is probably not your problem though because all that would happen here is that the first few feet of cold water supply line would be hot - the hot water expansion would not go very far. Also, this would not cause problems like the hot water in your toilet tanks.

2. You have a leak somewhere between the cold inlet to the water heater and the main meter. If there is a leak in this part of the system, it is possible for cold water to be drawn backwards from the water heater and out through the leak. This would cause hot water from the WH to fill the cold water supply line. If the leak is located before the main line splits to go to the cold leg and the water heater supply, then this hot water could be drawn back through the supply and be routed back through the split that supplies the cold to the house fixtures. However, if this is the problem then there is not only going to be hot water drawn back from the water heater but also cold water from the main supply leaking out of the hole. You should have a lot of water around if you have a basement or crawl space or a big damp spot in the yard if the leak is in your main line underground.

3. Your main supply is siphoning water back. As mentioned earlier, if your municipal water systems backflow preventer has failed, then the pressure of water in the community system main line will suck water back from your house as it passes by your connection to your meter. This is bad for you and bad for the community system - it's also their problem to fix. This would cause all the problems you describe as the hot water would be pulled back from the tank, past the junction of your house cold supply and could then be supplying hot water to your cold side of the house.

3A. Much like above except you are on a well instead of a community water supply. Here all it would take is a bad check valve in the system or a ruptured bladder in your pressure tank. Your system would operate but as soon as the pump turns off water would drain back down into the well -creating a backflow that would suck water from your water heater.

Your pressure regulator is not the problem. If it fails, your pressure is off but that's all it can cause. Any check valves are a part of the municipal water meter or in your supply lines from well to pump.

On edit with one other thought: How far from your water heater is the 'T' that splits the cold water supply to the water heater and to the rest of the house? The closet to the water heater that this 'T' is increases the chances of either a siphoning in the main line or an overheating water heater causing your problem.

This message has been edited. Last edited by: Jaybee,

I am on city water. The hot water heater sits about 2 feet from the main water shutoff valve/pressure regulater, however the entire garage is finished so I cannot see the "T". The hot water line from the WH has an expansion tank attached to it. I haven't found any dampness in my yard or floor. The house is built on a concrete slab foundation, no crawl space or basement.

I was sitting here trying to list all the obscure things that could cause this problem to help you trouble-shoot but instead I think there may be a simple solution. Since the supply line must split to provide cold and a cold supply to the WH after the pressure regulator and the regulator is only 2 feet away from the WH, then even a small amount of back flow could enter the cold supply to the rest of the house. I'm still leaning towards calling in somebody from the water department to check things at their end (this should be free) but try this for a simple fix:

Get a one-way check valve and install it in the cold supply to the water heater. This will completely prevent any possible back-flow to the rest of the cold supply system.

The plumbers that replaced the dip tube in the WH are returning tomorrow, Monday, since their fix was not a fix. I will suggest the one-way check valve to them. I will also call the city water department tomorrow. Is the backflow preventer device different or the same as what I have heard "stop and waste" valve that shuts off the water to the sprinker irrigation system?
(My lawn sprinkler water is also warm. Water lines are not buried deep here because the ground doesn't freeze, but the water seems warmer than it should be.)

I'm talking about a one-way check valve where the cold water supply enters the water heater tank. Not a normal install, but could solve your problem.

There should be an anti-backflow device as a part of your water meter..but maybe not.

Since your lawn sprinkler is tied into the same cold water supply as the rest of the house, it is just as likely to get hot water as your toilet or anything else.

Are you totally sure that somewhere in the plumbing somebody didn't screw up and swap the hot and cold lines? It could be an original problem that the former owner just never noticed.

I'm not totally sure, but if I turn off the cold water inlet to the WH I don't get hot water filling up the toilet.
I'm trying to find out why the hot water is being pulled back out of the cold water inlet of the WH to the main cold line. Its wasting energy and it isn't right. Your suggestions of installing a one-way check valve on the cold water line of the WH and contacting the water dept about the anti-backflow device are first on my list for tomorrow.

quote:

Originally posted by walden:
I'm not totally sure, but if I turn off the cold water inlet to the WH I don't get hot water filling up the toilet.

You shouldn't since there will be no pressure on the hot water side of the plumbing. Other than any hot water already sitting in the lines, if you cut off the cold supply to the water heater then no hot water should be moving at all.
I'm trying to find out why the hot water is being pulled back out of the cold water inlet of the WH to the main cold line. Its wasting energy and it isn't right. Your suggestions of installing a one-way check valve on the cold water line of the WH and contacting the water dept about the anti-backflow device are first on my list for tomorrow.

All I can add at this point is: Good luck!

I don't like the idea of a check valve in the cold supply line to the hot water tank. reason being is, in case of overheating and a possibly failed safety relief valve, there ain't no other way to vent overheated (overpressured) water except for the water heater to blow up.

item 1: put a bucket under the safety valve outflot pipe and lift the test lever. should flow clean, hot water (oh yes, not a plastic bucket.) let go of the test lever. the flow should stop. the outlet might dribble a bit, and it might not stop, but the flow should stop.

if it doesn't... or if you don't get discharge water flowing at line pressure, STOP. turn off the heater. call a plumber pronto. while waiting for them to answer, stick a thermometer in the bucket. if it's over 140 degrees, they need to know that.

I don't like either idea.

1. I don't like the idea of installing a check valve because it won't do anything to stop the flow through the cross connection and therefore wouldn't prevent the flow of hot water into a toilet tank. If there's a cross connection in the house, and there's less resistance to flow through the hot supply piping into that toilet tank than through the cold supply piping, hot water is going to flow through that cross connection into the toilet tank with or without a check valve upstream of the WH. I see no reason why a check valve in that location would change the cross flow problem the OP has.

2. I don't like the idea of opening the T&P relief valve on the water heater because those times when the local boiler inspector took it upon himself to open that valve on my WH, I was lucky to get that T&P relief valve to STOP dripping. As often as not, the relief valve would keep dripping until you replaced it. On apartment blocks, commercial water heaters like the A. O. Smith BT251 only last about 5 to 7 years, and so I got in the habit of keeping the old pressure relief valve every time I had to replace my BT251 heater. That way, if I needed a P&T relief valve that wasn't leaking, I could just use an old one rather than dish out $200 for a new one. IMHO the relief valves on water heaters and boilers are best left alone if they're not leaking.

I concede that commercial water heaters may be different in that respect than residential water heaters. After all, my BT251s only had a 60 gallon tank, but they'd supply enough hot water for 21 apartments every morning. So, maybe there was more scale formation in them than in a residential water heater. Still, I'd be as open to the idea of opening the relief valve on a water heater unnecessarily as I am to the idea of going over Niagara Falls in a wooden barrel unnecessarily.

This message has been edited. Last edited by: Nestor,

I agree that the check valve is not conventional but for safety - there is the regular pressure release valve plus Walden has confirmed that there is also an expansion chamber tank. Both would have to fail for the WH to blow. Even with a check-valve, there is not much difference - all you are removing is the distance of the main line back to the meter for expansion room - not enough to keep a WH from blowing if all other safety measures have failed. Also, my suggestion for the check valve is more of a trouble-shooting method than a fix, even if it dies solve the problem. If putting in a check valve solves the problem then this would confirm that the problem is not inside the house, but rather with the main line or meter.

I'm with Nestor on the checking the pop-off valve thing. I can't tell you the number of times I've seen one "tested" just to make sure it's not clogged - only to find that the darn thing will not not stop dripping. I think it's a case of calcium getting up inside the seals, but the only real fix is to install a new pop-off valve.

A city water guy came out yesterday, but didn't check the backflow prevention device. He checked the water pressure and it was 105. He recommended replacing the PRV and see if that solves the issue.
I changed the PRV set pressure to 60. The hot water is still backflowing from the cold water inlet valve but not near like it was previously. Question - should the expansion tank be installed on the hot water line or the cold water line to the WH?

It really doesn't matter as long as water expanding in the hot water heater has a direct route to the expansion tank.

Most people put the expansion tank on the hot water piping just downstream of the hot water heater. I think it would probably be best to also install shut off valves and unions on both side of the expansion tank so that you can replace it should that become necessary.

105 psi is an awfully high water pressure. Here in Winnipeg the water pressure typically stays around 40 psi.

Walden:

I would consider renting or perhaps even buying an infra red video camera. Unlike electrical wiring, water pipes are typically notched into the fronts of wall studs. I'm thinking that the heat from water pipes may show up as a lighter area along the wall where the water pipes are.

I'm thinking that if you could find a way to cause that cross flow when you want it to occur, you could then inspect the house using an infra red video camera to "see" hot faucets and hot exposed pipes (as well as pipes notched into studs behind drywall). That way, you could "see" what's happening and better determine where the hot water is getting into the cold piping and vice versa.

It wouldn't do any harm to find out how much such cameras rent for, and how much the cost to buy.

I just watched a program called "ask this old house " and they solved a similar problem. It seems that the diaphram in a single lever shower valve was deterorated, allowing hot water to flow into the cold water line. The sympton was that the hot water was comming out the cold water faucet as well as sending hot water to the toilet tank before finally getting cold water out of the faucet.
I don't know if this is what is causing your problem, but it is something to think about. But anyone elses ideas trump mine.