–Cold snap: How to avoid problems with your air conditioner and freezing of pipes
The outdoor unit of an air conditioner
An air conditioning system consists of two units, an indoor unit and an outdoor unit.
The outdoor unit is equipped with a compressor and a heat exchanger. The compressor is responsible for moving all the refrigerant contained in the refrigerant lines to transfer energy from the inside of our system to the outside, and vice versa. The heat exchanger, on the other hand, as the name suggests, is responsible for exchanging with the urrouding air.
Outdoor air conditioners that are directly exposed to weather are resistant and can withstand climate fluctuations such as rain, wind, hail or snow. This is because they are designed so that drops of water or snow do not reach the parts that could be damaged. However, keep in mind that they can freeze in very cold weather.
Defrosting in the outdoor unit as a solution
We know that a heat pump system suffers when it has to heat in negative outdoor temperatures. When the street temperature is below zero, the temperature of the outdoor unit's heat exchanger must be below 0 ºC to exchange energy, so the likelihood of ice formation is very high.
At Hitachi Cooling & Heating, we value your comfort. That's why we have an intelligent de-icing system that has two main objectives. The first is to eliminate frost before ice forms to minimise defrosting, and the second is to maximise air conditioning times in heating mode.
The elimination of frost (before ice forms) is achieved, becuase the heat exchanger of the outdoor units is divided in two, so that when the refrigerant returns from the indoor unit, it still retains a certain temperature that allows it to melt the frost in the lower part of the heat exchanger. On the other hand, it has a hydrophilic coating that prevents water droplets from concentrating on the fins of the heat exchanger, slipping off and falling into the lower part of the heat exchanger where the refrigerant has a certain temperature, which also improves the energy efficiency of the heat exchanger.
In order to maximise the air conditioning times in heating mode, we have sophisticated software that is able to measure various parameters, such as the operating time of the unit in heating mode, the measurement of the outdoor temperature and the knowledge of the operating point of the cooling circuit at any given moment. When the unit is defrosted, we can use this data to determine how much ice or frost is inside the unit and thus maximise the heating time if possible.
Snow has accumulated on the outdoor unit
Snow can accumulate and freeze between the heat exchanger and the outdoor panel, preventing good air exchange in the heat exchanger and thus reducing operating efficiency.
It is important to protect the outdoor unit from direct snowfall. Therefore, it is recommended to place the unit at least 5 cm above the ground and install a cover to prevent snow from accumulating on the unit.
You should be aware that the outdoor unit of your air conditioner can freeze just like an indoor unit. This freezing will cause the entire outdoor exchanger to ice up, preventing good air exchange in the outdoor unit and thus reducing performance.
Since this unit is outdoors, it is much more difficult to notice when the air conditioner freezes.
When an air conditioner freezes outdoors, it may cause the unit to stop cooling or even cause its components to fail. The reason for this freezing can be a number of factors, such as low ambient temperature.
Freezing in pipes and water meters
This low temperature also directly affects other elements such as pipes and meters.
Preventing pipes from freezing is essential if you do not want your system to be affected by low temperatures. For this reason, we want to provide you with these tips to help you prevent pipes from freezing:
- Avoid standing water.
- Let the heat circulate in the furniture through which the pipes pass.
- Turn off stopcocks and empty pipes.
- Insulate pipes.
- Keep the heating on at night.
- Use a hairdryer or other heat source.
We also recommend turning on a tap with a small trickle of water during the night if very low temperatures are forecasted. If you are not going to be at home, close the stopcock and empty the installation so that it does not freeze.
Special attention should be also paid to meters, which are elements that can be easily affected by low temperatures:
Firstly, you should protect the most exposed water meters, taps or pipes with insulating material to prevent them from freezing.
Next, you will have to insulate the meter and the uncovered pipe sections with fibreglass, rock wool or other insulating materials such as newspaper, foam shells or expanded polystyrene.
Technicians advise to protect the meter from frost by simple measures such as placing some cork-pan on the front and back of the meter box. You can also put bubble wrap or newspaper in a plastic bag to prevent it from getting wet, or you can even cover it with old clothes. Using these measures, the meter can withstand temperatures as low as -11 or -12 degrees Celsius.
Also, covering the pipes around the counter with polyurethane foam, expanded polystyrene or other insulating material will help prevent and avoid potential problems.
If you are going to be away from home for a long period of time and the water in the indoor installation will not be running, we recommend that you turn off the water inlet tap and drain the indoor installation: this will prevent breakage due to freezing. If the meter freezes and the house is without water supply, you should not force the stopcock.
Now that we are living with very low temperatures, there are many factors to take into account. The risk of freezing is higher than ever, and to avoid it, we must prepare the outdoor air conditioning units, pipes and meters, etc. This will ensure that your systems are not affected and that they perform optimally.
If any of these elements should be altered, remember to follow the advice and recommendations and never force the mechanisms.
by Hitachi Cooling & Heating
