The usual advice in case of frost and heating outages sounds simple: drain the water from the system. In reality, this solution has its risks, and in many cases it is worse than the alternative. Let’s break down how to act correctly, as well as what to do if the pipes are already frozen, since it is here that the most common mistake costs the most.

The Most Important Decision: Keep It Warm or Drain It

If the house is empty, but there is an opportunity to maintain heating, the simplest and most reliable way to protect the system is to leave it operating at a minimum level. The guideline is a temperature of approximately five to ten degrees above zero, which is enough to keep the water in the pipes from freezing. The reason why this option is often better than draining is that completely emptying the system has two serious disadvantages. The first concerns corrosion. Metal radiators rust not from water, but from oxygen, and an empty, damp system rusts approximately ten times faster than a filled one. In one season of dry downtime, steel radiators can be significantly damaged. The second concerns residual water. It is almost impossible to completely drain water from underfloor heating or from the lower points of radiators without a compressor, so this water will remain, freeze, and locally burst the pipe. That is, draining is the right solution for a dacha that is left without heating for the entire winter, but it is not a universal answer.

If You Do Drain the System

For houses that will not be heated at all, this must be done correctly, since partial draining creates an illusion of safety. The most common mistake is to open only one drain valve, after which part of the water remains in the pipes and radiators and will freeze in winter. The correct procedure requires that, in addition to the main drain valve, you open the valves at the highest points of the system, that is, on the radiators, so that air enters the system and the water can drain completely. Keep an eye on the pressure gauge and wait for the pressure to drop to zero before considering the job complete, since residual pressure can blow off a hose or strip a thread. You need to drain not only the heating system, but also the plumbing, including the water heater tank, toilet, and hydroaccumulator, since the water in them also freezes and destroys the equipment. For a well, it is also worth separately turning off the power supply to the pump so that it does not switch on accidentally.

Non-Freezing Heat Transfer Fluid

For private houses and dachas where outages can be prolonged, there is an alternative to water, namely special non-freezing fluids for heating systems. They do not freeze at temperatures at which water has already turned into ice, so the system remains intact even without the boiler operating. There is an important caveat here. Not every boiler and not every system is designed for such a heat transfer fluid, since it has different properties than water, so compatibility must be clarified in the boiler documentation or with a service center before replacement.

Insulation and Heating of Problem Areas

Metal pipes, namely steel and copper ones, have high thermal conductivity and cool down faster than plastic ones, which is why they freeze first. Insulate pipes that pass through unheated spaces, namely basements, attics, garages, and balconies. For areas that cannot be protected by insulation, a heating cable is used to maintain the temperature above zero. Special attention should be paid to the water supply inlet into the house, since this is where the cold penetrates the most. The trench should be below the freezing depth, which for Kyiv is approximately from ninety centimeters to one meter twenty, and the inlet itself should be insulated. For a well or caisson, insulate the hatch and walls.

About the Open Tap

A common piece of advice is to leave a tap slightly open so that the water constantly moves and does not freeze. This should not be considered a reliable method. A slow flow can still freeze, and in some cases this creates problems with the sewage system. Relying on this method as the primary protection is not advisable, especially in severe frost.

If the Pipes Are Already Frozen

This is the most important section, since the intuitive action here is the most dangerous. Do not turn on the boiler immediately. If there is ice somewhere in the pipe, there will be no circulation, and the boiler will overheat and boil literally within a minute, which can lead to the destruction of the heat exchanger or bursting pipes. The correct sequence of actions is as follows. Shut off the water supply and turn off the heating if this has not already been done. Find the ice plug by carefully feeling the pipes and radiators. It usually forms in corners, at narrowings, near windows, and where the pipe enters the wall. Thaw it slowly, starting from the open tap toward the frozen section, so that the water that is melting has somewhere to flow. Forget about open flames, that is, blowtorches and burners, since you will simply melt plastic pipes or aluminum radiators, and near building materials this is also a fire hazard. Use a heat gun carefully without directing it at a single spot, or use heating pads and warm water. Start the system only when you are sure that the ice has completely melted and circulation has been restored. If a pipe has already cracked or you are not sure about your actions, this is a job for a plumber, and it is better to spend money on a call-out than on replacing the boiler.

If You Live in an Apartment

In a high-rise building, the situation is different because the heating system is shared. Do not open or shut off the valves on the risers yourself, since this affects the entire building and can create problems for neighbors. If the heat supply has stopped and there is severe frost outside, contact the condominium association (OSBB) or the management company, since they make the decision about draining water from the building’s system. During massive attacks, city authorities in some cases supplied heat themselves at reduced parameters or drained water from radiators to prevent the system from freezing. I wrote separately about how to keep heat in an apartment without heating.


Sources

Rozetka blog, publications by UNIAN, NV, Warmwell, “My Plumber,” materials from specialized water supply and heating companies