Hot water flows from a cold tap: reasons

Residents of city apartments often encounter minor problems with plumbing equipment. And calling experts to eliminate them is not always cost-effective. Sometimes it’s easier to find the cause on the Internet and try to eliminate it on your own. If hot water suddenly flows from a cold water tap, most likely the residents are to blame. This phenomenon may have several causes and solutions. Some of them will require time investment, and in some cases you will also have to invest money. Let's consider what can be done if hot water comes from a cold tap.

main reason

If hot water flows from a cold tap, there may be several reasons. Hot water itself cannot enter the cold water pipe. Pipes with heated and cold water have different pressures; in the DHW channel it is higher. But due to incorrect connection or operation of the devices, hot water under higher pressure displaces cold water from the pipe.

Unfortunately, this phenomenon affects not just one apartment, but all floors with a common riser. If such a problem arises, it is not a fact that the cause is in your apartment. You have to think with your neighbors why warm water comes out of a cold tap. You can check this as follows: at the entrance to the house, close the cold water supply shut-off valve, then open the cold water tap in all apartments. If nothing leaks, then everything is fine. Where the water flowed, you need to look for a fault.

If, during the check, none of the residents have water flowing, then the reason lies in the pipeline. You need to ask your neighbors which of them installed the water supply recently. If this was done incorrectly, when pressure increases in the pipes, pressure occurs and hot water displaces cold water.

How to determine the cause in a particular case?

First of all, you need to try to localize the problem.

It is recommended to move away from the location where the problem was detected:

Check whether the flexible hoses are connected to the mixer correctly. Sometimes there is confusion when repairing or replacing it.
Touch the risers with your hand and determine their temperature. Usually, every owner knows where the hot water supply or cold water riser is (you can also be guided by the color of the meters). If no changes are detected, the problem is somewhere in the apartment. If the cold water riser is hot, the problem should be looked for in the area where it is connected to the boiler or the general pipeline.
Find out whether these problems exist for neighbors on the upper and lower floors.

If it turns out that the source of trouble is located in the apartment, you need to find it. You can find out which of the plumbing or household appliances creates the conditions for mixing by sequentially disconnecting them from the water supply system.

Often the problem appears after installing a new device or repairing existing plumbing, which gives reason to consider these devices to be sources of trouble.

Incorrect use of the bidet

A bidet is a hygienic shower. For water to flow, you need to open the faucet and press the button. After finishing the water procedures, you need to press the button and close the tap. But many simply turn off the button, leaving the mixer open. In this case, hot water is mixed with cold water and flows out of the taps in this form. Neighbors can turn on cold water, then the pressure in the system drops. Consequently, hot water will displace cold water.

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Due to pressure differences, hot water flows through cold pipes. To avoid this, you must remember to close the bidet faucet.

How to fix the hot water overflow problem?

Sometimes situations occur when only hot water flows from two water supply taps at once. To avoid such a situation, it is necessary to have a check valve on every riser in every bathroom in the house . This phenomenon will not only cause inconvenience in the operation of installed devices, but can also lead to injuries and burns not only in the current room, but also in neighboring ones.

For example, if there are about 30 apartments in a building, and in at least one of them there is no valve on the riser, then there is a risk that in one of the neighboring apartments, when opening a cold water tap, a resident may be scalded. Therefore, you should consider installing such a valve for safety reasons. If there is no check valve on the riser, then the cause of squeezing can be any device that supplies both hot and cold water.

During the installation or replacement of plumbing fixtures, if shortcomings are found in the operation of the devices themselves, in the absence of a check valve, the entire responsibility for overpressure will lie solely with the owner of all devices and installations. Installing a check valve is something that needs to be done in order for the devices to work correctly and for the correct supply of water from cold and hot water taps.

Incorrect boiler connection

Due to poor installation of the water heater, this problem can also arise. If you have recently installed a boiler, then you don’t need to think long about why the malfunction occurred. Just check that the installation is correct - if there is no check valve, heated water will flow into the riser with cold water. Due to pressure changes, the water heater itself may break. Typically, a check valve is placed under the water tank after the shut-off valve.

It is very important to use the boiler correctly. Before use, you must close the DHW valve and unscrew the inlet and outlet taps. If the valve remains open, the heated water will flow into the cold water pipes.

To avoid squeezing in the pipes, after using the boiler, you must repeat the steps in the reverse order. Close the inlet and outlet taps and open the shut-off valve.

Incorrect installation of the faucet

Often apartment residents change faucets themselves. If an inexperienced person does this, he may install the faucet incorrectly. The whole secret is to carefully tighten the fastening washer. This is why the installation may fail and hot water will flow instead of cold water.

If you are sure that the mixer is installed correctly, it is quite possible that it has deteriorated during use. Most often this happens with old taps installed in the Soviet era. Over time, the following breakdowns occur:

The gasket rots.
The mixer cartridge loses its seal.
The oil seal is worn out.

A factory defect in the mixer may also be the cause. Unfortunately, this is not uncommon, so it is better to choose high-quality fittings for which the manufacturer provides a guarantee.

Replacing a faulty faucet cartridge

If water involuntarily mixes in a single-tap faucet, and the flexible hoses that are hidden under the sink or bathtub have already been checked and connected correctly, then the internal cartridge needs to be replaced. In general, this work does not cause difficulties and is performed according to the following algorithm:

Release the cabinet under the sink and remove the plastic button under the lever, then remove the screw.
Now remove the lever, unscrew the fastening ring on the top of the sink, be careful not to break the body.
Remove the worn, damaged cartridge from the faucet base and install a new element in its place.
Make sure that the cartridge enters the faucet as correctly as possible (that is, it acquires the correct position inside the body within the boundaries provided by the protrusions).
Next, press the new cartridge with the fastening ring, install the faucet on the sink, correctly connecting the flexible hoses with the outlets, and secure the lever.
Place a plastic plug at the end.

Gasket wear

This problem occurs in most situations when hot water flows instead of cold water. Rubber gaskets in faucets can last 10 years, but according to the rules, they should be changed every 2-3 years.

An indicator that it is time to change the gasket is the hum of an open tap. Over time, the rubber wrinkles and the water begins to vibrate due to strong pressure. This is what causes the unpleasant sound.

You can change the gasket yourself.

Turn off the water.
Remove the faucet, disassemble it and remove the gasket.
Place the new rubber band in place.
Assemble the faucet, install it and turn on the water.

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If the unpleasant sounds have disappeared and cold water comes out of the cold tap, then you have done everything right.

What should I do to solve the problem?

Let's consider the procedure for solving problems of different types.

Wiring errors

Tangled hoses connecting the mixer to the hot water and hot water pipes are one of the easiest problems.

To eliminate it, you must perform the following steps:

Turn off the common cold and hot water supply taps to the apartment.
Open the tap and release the water pressure, drain the remaining water from the pipes.
Disconnect the flexible hoses from the plumbing fixture or from the pipelines: there is no fundamental difference here, proceed as is more convenient.
Reconnect the hoses in the correct position.
Turn on the water and check that the connection is correct.

If several devices were replaced, it is recommended to check all of them for correct connection.

If the problem occurs on a single faucet and does not cause much concern, you can simply swap the plastic buttons on the valves (blue with red).

Incorrect use of bidets

A hygienic shower (or bidet) has one design feature - in addition to a regular mixer, it has a water supply button.

Flow comes out of the shower head only when it is pressed. This is convenient, but many users do not close the faucet, believing that just releasing the feed button is enough. As a result, the hot and cold water pipelines are connected.

The hot water flow gradually squeezes out cold water and takes its place. The solution to the problem is simple - after each use, turn off the water supply to the bidet mixer.

Incorrect boiler installation

This problem occurs quite often. When installing a boiler, the pipelines are swapped, releasing cold water into the hot water riser and vice versa.

The problem occurs not only in apartment buildings; owners of private houses often make this mistake when assembling an autonomous water supply system.

Sometimes the pipes are confused when installing residential storage tanks. To solve the problem, it is necessary to correct the connection of the pipelines.

If the problem was created by the employees of the management company, you need to file a statement (collect signatures from neighbors) and resolve the issue.

No check valve

A check valve prevents flow from flowing in the opposite direction.
When all the taps are closed, the supply pipelines turn out to be dead-end lines. If the system has the ability to connect flows, hot water will begin to be pressed into the cold line. To solve this problem, it is necessary to install a check valve in the gap in the DHW line (usually it is installed immediately at the outlet of the meter).
The procedure is simple; the main task is to choose the correct location for installing the valve. It is necessary to take into account that in some cases one common valve is not enough and it is necessary to additionally cut off the flow from problematic plumbing fixtures.

Faucet problems

Mixers are the most problematic devices , since their task is precisely to connect two flows.

If the design of the mixer allows you to shut off only the water supply without cutting off the flows from each other, the process of mixing hot water will occur constantly.

The solution to this issue can only be replacing the problematic mixer with a new model of a different type.

Sometimes the reason that hot water flows from a cold tap is the wear of the cartridge in a single-lever mixer. The working disks no longer fit tightly against each other, and the hot flow begins to pass into the hot water pipeline.

Replacing the cartridge is not difficult:

Remove the plastic button under the lever and loosen the fastening screw.
Remove the lever.
Unscrew the fastening ring on top of the housing.
Remove the worn cartridge and insert a new one in its place. You need to find the correct position of the element so that it fits into the slot exactly above the hot and cold water supply openings. For this purpose, there are special protrusions in the body.
Press the new cartridge with the fastening ring, install and secure the lever.
Install the plastic plug.

Before starting the replacement, you must turn off the water supply. It is recommended to go to the store for a new cartridge, having the old model with you as a sample.

Gasket wear

Sometimes the cause of the mix-up is a worn gasket between the union nut and the tee of some plumbing fixtures. It needs to be changed periodically.

When it is discovered that the cutoff is broken, and if there is an admixture of a hot flow, it is necessary:

Turn off the water and release the pressure by opening the tap.
Unscrew the union nut, remove the worn one and install a new gasket.
Tighten the union nut, supply water and check the operation of the unit.

This work is not difficult; the only requirement is to purchase a new gasket of the required size.

The need to replace the oil seal

The oil seal can cause mixing of flows if it is located in the mixer connection unit. If hot water comes out of the tap, the seal should be replaced.

To do this, you need to perform the following sequence of actions:

Turn off the water and disassemble the defective tap.
Remove the worn oil seal and wind a new one. It is recommended to strengthen it by lubricating it with grease, oil or Unipak paste.
Press the winding with the stuffing box nut and reassemble the valve in the reverse order.

Faucet wear

If replacing the gasket does not help, the mixer will have to be disassembled again. You need to check whether the gasket was installed correctly. When you are convinced that your actions are correct, but hot water still comes from a cold tap, you need to change the faucet completely. In modern cranes, other parts may wear out and cannot be repaired.

It is necessary to choose a high-quality device so that it does not break immediately after installation. It is better to give preference to more expensive options from reliable manufacturers.

Debugg

Often the appearance of hot water in a cold pipeline is a malfunction that cannot be eliminated without a specialist, however, in some cases you can handle it yourself. At the same time, you need to soberly assess your strengths and be aware of the possible consequences; after all, plumbing is a serious matter.

Wiring errors

If, during repair work in the basement of a residential building, mechanics mistakenly connected pipes from different mains, only they can correct the situation. There are no other options, you need to call the management organization and demand that measures be taken. Symptoms of the malfunction are the following: recent renovations in the basement and hot water flowing from the cold or from both taps of all apartments connected to the same riser.

Another situation is possible - the owner of the apartment himself recently made changes to the configuration of the pipelines of his apartment, changed pipes, installed new plumbing. The cause of the malfunction may be his actions. Before calling the experts, you should go through the system, check the correctness of the joints, and if an error is found, take measures to correct the situation.

Oil seal wear

If everything is fine when your tap is closed, and no water flows anywhere, but when the cold valve is open, hot water flows out from under the cold valve, then you need to change the seal. It could have worn out from long-term use.

The fix is quite simple. Here's what to do:

Use an adjustable wrench to unscrew the packing nut.
Tow, lubricated with oil or grease, should be wrapped in a thin layer around the valve rod.
After this, the nut is screwed back on. You need to do this carefully so that the water continues to flow from the tap as usual.

Another solution to the problem is to change the oil seal or the entire valve.

Consequences

If the cause of this phenomenon is incorrect installation of plumbing, then the residents are to blame. Consequently, the management company is not responsible for breakdowns caused by this problem.

Boiling water from a cold tap is unpleasant, but there are other consequences. For example, some appliances are not designed to handle hot water. These include:

Cold water meter.
Toilet cistern.
Cold water pipes.
Toilet flush mechanism.

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If these items become unusable due to your fault, then the responsibility lies only with you.

Legislation regarding tap water temperature

The modern Housing Code clearly sets out the requirements for the temperature of water supplied to a residential building. The figures are determined by sanitary and construction standards, as well as GOST.

According to the approved values, the temperature of hot water should be kept between 60 ⁰C and 75 ⁰C. Discrepancies with the standards are acceptable and are also recorded in regulatory documents. So, from midnight to 5 am the error can be a maximum of 5 ⁰С, and from 5 am to midnight - only 3 ⁰С. Water from a hot tap colder than 40 ⁰C is charged as cold.

Preventing the problem

You can protect yourself from a situation where hot water flows instead of cold. To avoid pressure differences, check valves can be installed at the pipe inlets. Or you can install modern water meters that have such valves.

When hot water appears in a cold water tap, there is no need to jump to conclusions. It is much more effective to get together with your neighbors and collectively discuss why this could happen. If someone has recently had their bathroom renovated, then it is advisable to look for the reason in this apartment.

To avoid such situations when hot water comes from a tap with cold water, or vice versa instead of hot water comes ice, you need to trust the installation of plumbing to professionals. Now you know what to do if such a situation arises, but it is better to avoid it altogether.

Why is this happening?

There may be several reasons for changing the water supply mode.

They can be divided into two groups:

problems caused by defects in plumbing or improper work in the apartment;
mistakes made by employees of management companies or other organizations when installing or repairing water supply networks and equipment.

Causes located inside the premises of an apartment building may be:

erroneous connection of a flexible connection during repair or installation of a new mixer;
failure of mixer parts, facilitating the penetration of hot flow into the cold water line;
improper use of plumbing or household appliances.

As a rule, the appearance of hot water instead of cold occurs in systems where the DHW pressure significantly exceeds the parameters of the cold line.

If the pipelines communicate due to equipment malfunctions, hot water begins to squeeze out cold water and take its place.
This phenomenon is called "admixture" .
Its cause is usually worn out seals, gaskets, poor-quality taps, etc. If the reasons are outside the apartment, then they are most likely caused by a mistake by the plumbers of the Criminal Code. For example, when performing repair work or replacing equipment, pipelines were mixed up.

Plumbers' mistakes sometimes occur, but the most common reasons should be considered to be malfunctions of plumbing fixtures in the apartment.