How to thaw frozen plastic plumbing. What to do if the sewerage and water pipes in a private house are frozen? Frozen water pipe underground

In a private house, where the water conduit is not properly prepared for winter, its freezing may be a logical conclusion. How to warm up a frozen water pipe depends on the material from which it is made, and the location of the frozen section of the water pipe: outside in the open air, in a cold room or buried in the soil.

Defrosting outdoor pipes

A poorly insulated water supply system, located in an unheated room or outside the house, freezes faster in extreme cold than in the ground. There are two most simple and affordable methods of heating the water supply:

hot air;
Hot water.

Both of these methods are suitable for heating frozen plastic or metal plumbing.

Hot water defrosting

Water is heated in a bucket or in a kettle (its amount depends on the extent of freezing), and poured onto the pipe until the layer of ice adjacent to its inner surface thaws. The faucet must be open at this time, and as soon as water can seep from the supply conduit between the pipe wall and the ice plug, it will flow from the faucet first in a small stream, and as it thaws, the pressure will increase.

To increase the efficiency of the operation, the pipeline should be wrapped with rags or other moisture-absorbing material - it will absorb liquid, increasing its exposure to frozen pipes.

The essence of the operation is that a stream of hot air is directed to a frozen section of the pipeline, its surface is heated, and a water layer is formed between the ice plug and the wall. When water starts pouring from the tap, its movement and further heating will melt the ice. As a heat source, you can use a heat gun or a building hair dryer. In the case of a metal plumbing, it is permissible to use an open flame of a blowtorch or gas burner. But you need to be careful not to start a fire, especially indoors.

You can localize the heat around the area to be heated by building a small tent out of plastic sheeting or other airtight material. This is especially effective when work is carried out outdoors at sub-zero temperatures.

Attention ! Be careful with plastic piping. Hot air should be supplied to the plastic in portions, without overheating its surface. If an ice block has formed in a short span of the water line, it is safer to use a regular hair dryer to dry your hair.

How to warm up a plastic frozen water pipe with a heating cable, watch the video:

Heating pipes in the ground

It is much more difficult to heat a water pipe that is underground, since for this you first need to dig it out. With the help of open fire, most often bonfires, the ground above the pipeline laying is defrosted and a trench is dug. When the pipes are freed from the soil, they are heated in the same way as the surface ones - with hot air and water.

Welding Machine Application

There is a way in which you do not need to dig a trench - this is to heat the water supply with a welding machine. One end of the cable is connected to the outlet of the pipe to the house, and the other to the valve located in the well. The defrosting time depends on the length of the area blocked with ice. Do not forget to keep the tap open, as the current of water that appears, first in the form of a thin stream, will contribute to a faster heating process.

Warning ! This method is only applicable to metal pipes wires. If there is a plastic insert between the two ends of the cable, the heating process will not occur.

How to prevent freezing

It is easier to prevent freezing of water in pipes than to eliminate its consequences later. Measures to prevent misfortune should be taken even at the stage of laying the water supply.

What can be done to prevent pipes from freezing:

Deepen the pipes into the ground below the freezing level of the soil;
Before filling up a trench with a laid water pipe, cover it with a heater, you can use a polypropylene cylinder for this;
Put waterproofing (thick plastic film) on top of the insulation. It will protect the insulation from moisture, and it will last longer;
Insulate carefully. outer pipe and at the exit from the earth;
In non-residential premises through which the water supply runs (veranda, terrace), maintain a positive air temperature;
In severe frosts, open the tap slightly to create a constant flow of water in the water supply.

You can take advantage of an effective innovation, and during the assembly of pipes, install a heating cable for the water supply in the areas that will be most exposed to negative temperatures. It is inserted inside the pipe and is connected to the network during the danger of freezing.

The lack of water in the water supply in a private house can be due to various reasons. One of them is the formation of an ice plug in the pipe. Such a nuisance occurs if the temperature is very low outside, and the rules were violated when laying the water supply. You can try to fix the problem yourself, but it requires considerable effort. Consider the answer to the question: water froze in a pipe underground - what to do in this situation?

Before figuring out what to do if the water in the water pipes froze, let's figure out why this can happen. Main reasons:

laying pipes at insufficient depth;
a small layer of insulation, its poor quality or complete absence;
insignificant or zero water consumption during severe frosts;
abnormal weather conditions.

As a rule, pipes passing on the street - outside or underground - freeze. But in the absence of heating and significant sub-zero temperatures for a long time, the problem may occur indoors or at the point where the pipe enters the wall.

Cork search

Before deciding how to warm up a frozen water supply, first of all, you should find the place where an ice plug forms in the pipe. Most often they are formed at the joints of the elements, but sometimes the structure freezes along the entire length. Search methods:

Visual inspection of the outer pipes. Due to the fact that water increases in volume when it freezes, ice plugs lead to the expansion of plastic elements. In addition, these areas feel colder to the touch than the rest.
Internal check. If it is not possible to inspect the pipeline, it should be partially disassembled and inserted into the hole flexible cable. As soon as there is an obstacle in the way of its progress, the traffic jam is detected. To determine its location, you should measure the length of the included cable.

The solution to the problem of how to warm up a frozen pipe with water depends on whether there is open access to the problem area, or whether it needs to be heated from the inside of the water supply system.

External pipe heating

If the water in the pipe is frozen, how to warm it from the outside? If there is open access to the area in which the ice plug has formed, it is not difficult to solve the problem. Before heating, be sure to open the taps so that the melted liquid can freely exit. The main methods involve the use of:

hot water;
warm air;
elements of the "warm floor" system (heating cable).

Hot water

This method is suitable for any pipes: polypropylene, metal-plastic, metal, and others. But the temperature of the water should be increased gradually so that the structure does not crack.

Wrap fabric around the frozen area. This is necessary to protect the pipe and distribute heat more evenly.
Place a container under the pipe to collect water.
Water the plot hot water within minutes.
Periodically wring out the fabric and repeat the steps until the water supply is restored.

Warm air

It is best to use a building hair dryer as a source of warm air. It should be directed to the area with an ice plug and held for a while.

If the freezing area is small and the pipe is thin, then you can use a regular hair dryer, but it should not work longer than 15 minutes in a row. It is advisable to wrap the pipe with heat-insulating material and let hot air under it. Such a "casing" will accelerate warming up.

It is useless to use a fan heater or an electric radiator, since they cannot be used to create a concentrated air flow. With a building hair dryer, you can safely defrost metal pipes. Plastic structures with inaccurate use, it can damage.

Heating cable

To heat a plastic pipe, you will need an electric cable that is used when installing a “warm floor” or a special cable for heating pipes. Action algorithm:

Wrap the pipe section with foil. Place the electrical cable on top.
After the cable, put a layer of insulation. Secure everything with tape.
Connect the cable to the network for 2-4 hours.

On a note: Metal constructions can be warmed up with a welding machine by attaching it to a frozen section of the pipe. It is also allowed to use open sources of fire - a fire, a blowtorch. For propylene and other plastic pipes, such methods are not suitable.

Internal heating of pipes

Consider what to do when water froze in a pipe underground. With a shallow depth and low hardness of the soil, it is worth digging a trench and applying some of the methods described above. If this is not possible, internal heating should be carried out. The main methods are based on the application:

steam generator;
homemade boiler;
hot water.

All methods assume the possibility of penetration into the pipeline. If it is missing, you should disassemble or cut out part of the structure, after blocking the water supply.

steam generator

To defrost the pipe, you will need a steam generator - a device that produces hot water vapor under pressure. Stages:

Pour water into the tank.
Connect a heat-resistant hose with a small diameter to the steam generator.
Insert the hose as far as it will go (up to the ice plug) into the water pipe. At the same time, there should be free space in it for the flow of melt water.
Turn on the steam generator. Wait until the ice begins to defrost. This usually takes 5-15 minutes. The amount of water in the steam generator tank must be monitored.

When solving the problem of how to heat water in a plastic pipe underground, if there is no steam generator, you can use an autoclave. The heat-resistant hose must be connected to the fitting of the appliance.

Homemade boiler

You can warm up the water supply from plastic using a homemade electric boiler. This method not suitable for metal structures. It involves working with high voltage, so you need to be careful.

Action algorithm:

Take a copper wire with two insulated cores (section - 2.5-3 mm).
Separate the wires and spread apart.
Remove the winding from one wire. Bend the second core in the opposite direction along the wire.
Tightly wrap the "bare" part 3-5 times around the fold. Cut off the rest.
Retreat from the turns of 2-3 mm. Strip the end of the bent wire. Wind it around the insulated wire 3-5 times. Trim off the excess. The turns of the first and second wires must not touch.
Connect the plug to the other end of the wire.
Insert the "boiler" into the water supply until it stops.
Plug in the plug. Under the influence of heat, the ice should begin to melt.
As the cork decreases, the "boiler" should be moved deeper.

Tip: When using a steam generator or "boiler", ensure that the melt water is drained. It is required to periodically turn off the device and use a thin hose and a compressor to pump it out of the pipe.

Hot water

The essence of this method is reduced to the impact on the ice in the pipe with hot water. For its "delivery" to the cork, you can use:

hydro level and Esmarch's mug;
pump.

The first option is suitable if the question arose of how to warm up a frozen pipe underground when the plug is far from home, and the system has turns and bends. Required:

building hydraulic level;
Esmarch's mug (device for enemas);
hardened steel wire.

Connect the hydraulic level tube and the wire along the length, making a loop at its end for greater rigidity. The edge of the tube should protrude 1 cm beyond the end of the wire.
Attach the second end of the hydro level to Esmarch's circle.
Push the device into the water supply as far as it will go.
Place a bucket under the pipe hole.
Pour hot water into a mug. It must flow through the hydraulic level tube to the ice and heat it. In this case, defrosted water will pour out of the hole in the pipe.

This method of heating requires a lot of time and effort. To thaw 5-10 cm of ice, you need up to 5 liters of hot water. The whole process can take 5-7 hours depending on the length of the cork.

If there is a pump, then it should be installed in a container in which water is constantly heated, and a heat-resistant hose, insert it into the water supply and supply hot water under pressure. The diameter of the hose should be such that there is a gap for the melt water to exit the pipe. It can be reused for heating.

Note: In the warm season, it is worth inspecting the water supply that has undergone defrosting. Deformed elements may need to be replaced. It is also worth taking measures to prevent the freezing of pipes.

Prevention

Freezing water supply is a problem that owners of private houses periodically face in cold winters. You can remove the ice plug yourself. The easiest way to restore the patency of the pipe, which has external access. If the structure is in the ground, then certain devices will be required. In difficult cases, it is better to turn to the help of specialists who have a powerful apparatus for breaking ice - a hydrodynamic machine.

No one is immune from minor communal problems. Plumbing can become clogged with rust or welding scale, leak, or, under certain circumstances, even freeze. Today we have to find out how and with what to defrost water pipes inside the house and on the street.

Reasons for freezing

Three scenarios can lead to freezing of the water supply system:

A residential building or utility room left without heating (summer kitchen, sauna, etc.). Usually in such cases, the water is turned off and dumped; however, in the case when all the taps are closed and only the vent in the lower part of the water supply circuit is open, the water often hangs in the pipes and forms an ice plug when the temperature drops below zero;

Incorrectly calculated depth of soil freezing;

Recall: water supply lines and water inlets to private and apartment buildings are laid below the freezing level, where the soil temperature is always above zero and only slightly changes during the year. However, the actual depth of freezing strongly depends on the type and density of the soil. Within one locality, it can vary by half a meter or more.

Frosts in combination with open laying of street water supply. This situation is typical for Crimea, where the author lives. Since negative temperatures are extremely rare here, water pipes are often laid along the facades of houses or simply along the ground. However, in rare frosts, the water still freezes.

Who is to blame - we found out. It remains to find answers to the second part of the age-old question: what to do.

To learn more about how water supply pipes can be defrosted, the video in this article will help you.

defrosting

First - a few simple ways to thaw frozen pipes.

How to defrost water pipes inside the house:

Very simple: heat the whole house or its separate room. To do this, it is not at all necessary to melt the stove or start the boiler: to warm up small kitchen or a bathroom, a fan heater, an oil radiator or even a gas stove is enough.

With hidden pipe laying in walls or screed perfect tool for their defrosting - an infrared heater. If it is equipped with a reflector, direct the heat flow to the surface under which the water supply is hidden. It is enough to hang a wall panel or a flexible picture heater on a nail driven into the wall.

How to thaw a frozen plastic (polyethylene or polypropylene) water supply inlet, laid at a shallow depth underground:

The simplest instruction: build a fire directly above the entrance.

This is how the soil was warmed up for decades for the repair of underground highways in the conditions of Siberia and Far East. It is better to use firewood for kindling, but coal is the main fuel: it can smolder for hours, releasing a large number of heat.

How to defrost steel pipe laid in the ground:

The easiest way to use it to defrost is ... a welding inverter.

Install a grounding crocodile at the input in the water meter well or at any other water supply point outside the house;

Close the electrode holder with the water supply in the house (for example, by winding it with a wire to a pipe stripped of paint);
Turn on the welder and set the current to 20 amps;
If the ice does not melt within 20-30 minutes, step by step increase the current by 10 amperes with an interval of at least 15 minutes until the water supply warms up.

How to defrost an openly laid steel water pipe with your own hands?

This is done using the simplest heating tools:

Blowtorch;

Improvised gas burner from a canister with a nozzle;
Building hair dryer.

The algorithm of actions is simple and clear:

Open any water supply faucet in the house;
Heat the pipe in sections of half a meter to a temperature of at least 50-60 degrees, until water begins to flow to the mixer.

What to do if during the defrost process your cold water pipe burst:

Water expands when it turns into ice, and the volume of ice decreases when it melts. However, until the moment of melting, ice behaves in the same way as any other ice. physical body- expands when heated. Therefore, frozen pipes most often break during thawing.

Use the gust to blow off the water and dry the plumbing completely. Heat the pipe along its entire length, making sure that there is no ice left in it. And only after that proceed to repair - welding a broken seam or replacing a section of the water supply.

How to warm up a plastic pipe laid along the street:

The most reasonable solution is to use a heating cable section to warm it up. Best of all - self-regulating: its device completely eliminates overheating and damage to the insulation of the cable or the water supply itself. The heating cable is wound around the pipe in a spiral and connected to the network; defrosting takes from 15 minutes to an hour, depending on the diameter of the water pipe.

Prevention

What can be done to ensure that you never need to defrost the pipes of the water supply system?

At underground laying insulate the water supply entry from above. It is from above - because in cold weather the soil freezes from top to bottom. The deep layers of the soil will become a source of heat for the pipes, and it is not necessary to isolate the input from them.

In case of forced laying of pipes above the freezing depth (for example, on rocky soils) or in case of open laying, provide them with a cable heating system. Passive insulation is unable to prevent freezing of water in pipes: it will only delay it. In the absence of water intake, the water supply input will still freeze, but only a little later.

The heating cable can be installed in two ways:

Image	Description
	Outside the pipe: the cable is wound in a spiral or laid under the pipe in a heat-insulating sheath common with it.
	Inside the pipe: a sealing sleeve with a rubber seal is used to enter the cable into the water supply system.

Which cable should be preferred? From the point of view of the author - again, self-regulating.

Here are its advantages over a somewhat cheaper resistive one:

Energy saving- power consumption decreases as the temperature rises;

Safety- cable overlap cannot lead to overheating and damage to the insulation and pipes, since with an increase in temperature, the specific power of the heating sections will decrease;
Arbitrary cut to length: a cable of any length, equipped with an end sleeve, is a ready-made heating section.

In comparison, the length of a resistive cable section with a fixed resistivity is fixed. If a conductor is shortened, its impedance will decrease and the current flowing through it will increase, which will lead to overheating.

Conclusion

As you can see, preventing a problem is much easier than fixing its consequences. To learn more about how water supply pipes can be defrosted, the video in this article will help you. Good luck!

When the water in the pipes freezes, it's not so bad. But if the water breaks the pipes, then there will really be trouble. Not that the water will blow the pipes to pieces, but the fistulas on the pipes will be good, not always collar will help. Therefore, if the water in the pipes is frozen, you should immediately call the housing office or another organization responsible for the operation of this network. True, the housing office is not Chip and Dale, and is usually in no hurry to help, in the private sector there are no housing departments at all, and companies involved in defrosting pipes are far from everywhere, and then you yourself have to engage in an unequal battle with the elements. Although, of course, you can wait for spring and completely change the pipes, the reasons for the freezing of pipes still need to be dealt with and eliminated so that this costume ball happens as rarely as possible.

First of all, pipes are heated where there are metal parts: valves, adapters. Since metal conducts heat and cold much better, freezing of water in plastic pipes in such places is most likely. You should also warm up places where there is an obstacle to the flow of water or the flow rate drops: at turns, bends, pipe branches.

From the point of view of physics, everything is quite simple here, in order to make a phase transition of a certain amount of matter from a solid state to a liquid state, energy must be expended. And to put it in a more understandable language, to melt 1 kg of ice, you need to spend 79.4 Kcalorie or 334 KJoule or 92.8 Watt hours. It remains only to choose how to transfer heat to ice. Most often, pipes are heated from the outside, transferring heat to metal pipes.

There are many ways to heat pipes, I will give only the most common:

1. Hot water (boiling water)

Pipes are wrapped with rags or foam rubber and periodically poured with boiling water. Although this is the most affordable way, it can only be used in the basement, sometimes in the entrance. If the pipe is frozen in the ground, then pouring boiling water on the ground is useless. It can take from 2 to 10 hours to defrost pipes in this way. If you can’t defrost pipes in this way, then you should think about another way.

2. Hot air

The source of hot air can be a building hair dryer, various kinds of electric heaters with fans (so-called "dukes") and without fans. This method has many disadvantages: firstly, plastic pipes must be heated very carefully so that the pipes do not melt, and secondly, low efficiency, since most of the heat is lost for other purposes. It can take from 2 to 10 hours to defrost pipes in this way. If you can’t defrost pipes in this way, then you should think about another way.

3. Thermal conductivity

Special wires are wound onto the pipe in a spiral, which are used to install underfloor heating, then the wires are connected to the electrical network. The disadvantage of this method is that such wires are usually sold in coils or sets and are not cheap, however, there are no simple and cheap ways to defrost pipes. It can take 1-3 hours to defrost pipes in this way. But the main drawback is that this method is not suitable for pipes laid underground.

4. From the inside

In order to melt the ice plug in the pipe, hot water is used, but it only needs to be somehow delivered to the ice plug or heated, for this you need a good entrance to the pipe.

Hot water can be driven into a pipe under pressure or made something like a boiler. These methods are enough, so I will not repeat. I will only add that pipes can be heated in such ways only on flat areas and it can take a lot of time - up to 2-3 days, but there are no other relatively simple and cheap ways to warm plastic pipes in the ground. If all else fails, then you will have to call a team with special equipment and they will arrange a hydrodynamic flushing of pipes for you.

If the water pipes in the ground are frozen, then there is only one reason - the pipes are laid at insufficient depth, i.e. above the freezing depth of the soil, which means that if the pipes are not laid deeper, then the water in them will freeze every cold winter. It is possible to determine the depth of soil freezing on the map . Main water pipelines large diameter, in which water flows constantly, can be laid at a shallower depth, and it is better to lay water pipes with a diameter of 20-32 mm below the freezing depth or, if this is not possible, immediately lay a water supply heating system together with the water supply.

If the water pipes periodically freeze, then so that the water in the pipes does not stagnate and freeze, you need to turn on the water in the apartment at night, the greater the pressure, the less likely the water will freeze in the water supply, though the more bills from the water utility will be, but there is no choice account for. And if you turn on the water with a little pressure, then the sewage system may freeze, but this is a slightly different topic.

Owners of private houses are often faced with winter time with the situation when one morning it suddenly turns out that water is not flowing from the tap: the water supply system has frozen. There are several reasons for the freezing of water in the water supply: a decrease in the air temperature outside to extremely low temperatures, insufficient penetration of pipes (without taking into account the depth of soil freezing), the water in the pipe is motionless due to low or zero flow (at night or in the absence of owners ), insufficient insulation of pipes. Usually, all of these reasons, taken together, lead to freezing of the water supply. What to do, is there a way out of the current situation, because without water, as you know, neither there nor here? Yes there is. Consider some methods of heating frozen water pipe, which, however, will require a lot of patience and some skills from you.

Overview of different ways

Plumbing can be defrosted different ways external thermal effects on the pipe, or by defrosting it from the inside.

Method 1. Use hot water

If there is a suspicion that the water supply system is frozen in an open area - at the entrance to the house, in an unheated basement, etc., boiling water is used to warm it up.

To do this, the pipe must first be wrapped with any rag that will absorb water, and to extend the contact time of the pipe with boiling water. Pour hot water over until the ice begins to melt. And to speed up the process, the tap must be left open.

The easiest way to warm up a frozen pipe is to pour boiling water over it.

This method is used only indoors, because if the pipe is underground, it will take a long time to warm it with boiling water - at least 12 hours.

Method 2. We use a building hair dryer

The pipe can be defrosted using the hot air produced by a powerful building dryer. The surface of the pipe is blown from all sides, and to reduce heat losses, it is recommended to build a small pavilion made of polyethylene film over a frozen pipe, for example. If the pipe is plastic, you need to correctly calculate the heating so as not to melt it.

Solving the problem of defrosting a water pipe with a conventional hair dryer, but you can also use a building

With a slight freezing of the pipe, you can use a household hair dryer or fan heater to warm it up. If there are turns, narrowings, entrances to fittings, they also need to be warmed up, as ice can get stuck there. And in this case, do not forget to leave the tap open.

Method 3. An electric current comes to the rescue

How to warm up a frozen water pipe using electric current?

Heating of a metal water pipe can be made using a welding transformer: the positive wire is connected to one end of the pipe, and the negative wire to the second. So in a simple way the problem can be solved in a few minutes: the ice plug will melt.

The time for thawing frozen water metal pipes with a welding transformer is minimal

Heating of plastic pipeline can be done with a two-wire copper wire section 2.5 mm. This method is similar to the principle of operation of a familiar home boiler. The wire strands are disconnected. One of them is simply bent, and the second is exposed and twisted 3-5 turns around the wire, cutting off the extra end. The same is done with the first core, retreating 2-3 millimeters from the turns of the second core. It is necessary to pay attention that the cores do not touch, otherwise a short circuit will result. A plug is connected to the other end of the wire. The wire is pushed into the plastic pipeline and connected to the electrical network. Passing through the water, the current heats it up, and the ice begins to melt. The method is good in that only water is heated, while the wires remain cold and this prevents accidental melting of the plastic pipe. To quickly blow out the melt water, you will need an additional compressor.

Method 4. We heat the pipeline with improvised means from the inside

How to warm the water supply if it has many bends and sections? For such a case, you can build a special device. You will need a wire, a hydrolevel tube, Esmarch's medical mug (in a simple way - an enema), which consists of a rubber container with a rubber hose and a small faucet for draining water. The hydraulic level tube is fastened to the wire with electrical tape so that the end of the tube is slightly longer than the wire. Push it into the water supply until it stops. Hot water flows out of the rubber tank into the pipeline. It is necessary to organize the collection of melt water.

Schematic representation of the warming process with wire and enema

As the ice thaws, the tube with the wire is pushed further. The process of heating a frozen water pipe with improvised means is quite laborious and requires a lot of patience and time (about 1 hour per meter of a frozen pipe), but the costs are minimal.

Method 5. Calling specialists

You can also warm up a water pipe from the inside with the help of special equipment - a hydrodynamic installation, the direct purpose of which is preventive flushing of water and sewer pipes.

Hot water with a temperature of 150 degrees is supplied under high pressure(90-100 atm) on the sleeve. Water boiler installation works on diesel fuel, and the unit - from the mains with a power of at least 7 kW and a voltage of 380V. For this method, you need to call specialists, so this method is not suitable for everyone.

How to prevent pipeline freezing?

First of all, pipes must be laid taking into account the type of soil and the depth of its freezing. To avoid freezing, it is best to lay the pipe at a depth of at least 2m. Well, if this is not possible, then you need to make high-quality thermal insulation of the pipeline or think about using a special heating self-regulating electric cable which is enabled when needed. In addition, all leaks must be repaired.

Freezing of the pipe can be avoided by using a special heating cable

It's important to know! Water often freezes in pipelines of small diameter, therefore it is recommended to use pipes with a diameter of more than 50 mm for plumbing.

Water can freeze in the plumbing where it passes through the basement or basement, as concrete freezes faster than soil. In such places, it is recommended to place the pipe in a sleeve (pipe with a large diameter), and inject polyurethane foam into the voids formed.

Underground water supply can also be protected from freezing with glass wool, mineral wool, foam strips, filling all voids with polyurethane foam.

High-quality insulation of water pipes will protect them from freezing

There is another option, which one of the experts will tell you about:

If not all of the above measures have been taken, and there are frosts on the street, one thing remains - contrary to safety regulations, leave the tap ajar at night and when no one is at home - the movement of water will prevent the formation of ice.