The failure of the group is that the heat exchanger is frozen. A building uses a cold water unit VAV air -conditioning system. From construction to debugging to the voting operation, there are 4 new group frozen accidents. The new group of the building has a total of 15 units and frozen frozen.The proportion of cracks is as high as 27%.The reason is the following 4 aspects.
a) The temporary pipeline supplys water without washing
In order to rush the work period, temporary heating is often used with fresh air units, but because the time is urgent to rinse the entire heating system, the water pipeline is used to return the connection method of the underlying pipeline.The unit heater is continuously accumulated, and the flow of hot water continues to decrease, resulting in frozen the heater.In essence, the temporary water supply pipeline failed to be washed up in accordance with the construction regulations and blindly invested in the use of frozen cracks of the heater.
b) The valve position indicated by the self -control valve is wrong
The construction of concentrated air -conditioning self -control systems is often lagging behind. It often starts to debug the weak electricity system after the building is officially invested.The fresh air unit can run normally before the self -control system is enabled, and a freezing accident occurs after use.The accident occurred during the installation and commissioning of the air -conditioning self -control system in winter. The installation of the installation of the water valve opening instructions of the fresh air unit was exactly the opposite of the computer instructions of the self -control system.ACCIDENT.So the outdoor temperature drops.When ° C below ° C, try to keep the air -conditioning system running stably. The self -control installation and debugging of the water system should be arranged in other seasons to avoid accidents caused by debugging errors.
c) The neonatal unit has water in the cooler when the fresh air unit is disabled
The refrigerator frozen accident occurred after the fresh air unit in the basement was suspended in winter, mainly due to the deposit of water in the refrigerator of the fresh air unit.The possible reason is as follows:
(A) The water running valve was not opened when the water was leaked, so that there was no channel for air into the cooler, so the water in the cooler could not be completely leaked, resulting in the cooling outdoor temperature in winter.Frozen.
(b) Because there is water in the cold water system pipeline, the position of the fresh air unit is lower than the system main pipe of the system. If the valve connecting the pipe road is closed, the water is slowly exuded from the cold water to the water pipe to the refrigerator.Therefore, although a leakage operation is performed, it will still cause frozen cracks.
The accident may be caused by one of the above two reasons, so improvement has been improved in both aspects. The higher point of the reflection of the water pipe of the fresh air unit is added to the higher point of the water pipe.It can be used in water, especially to ensure the thoroughness of the leakage; add a set of valves to the water pipe road of the fresh air unit to completely cut off the slow seepage problem after the downturn was leaked.
D) The self -controlled anti -freezing protection device of the fresh air unit is out of control when the flow of the heater
The new wind air -conditioning unit must ensure the rated water flow during winter. If the water flow is too small, the heater will cause a freezing accident.The air output parameters of the fresh air units serving the standard layer of the building remain unchanged, and the heat flow in the heater remains unchanged. Therefore, there are rarely frozen cracks in such fresh air units.The fresh air crew located in the basement serves the underground kitchen and restaurant of the building. Because the kitchen exhaust requires a lot of air -conditioning to make up the wind, the new wind unit must bear the function of the outdoor new air treatment (at the same time to supplement the wind), and it must meet the indoor indoor indoorThe adjustment of air temperature.
In the severe cold weather in winter, the air -conditioning load in the basement is small. When the operator finds that the room temperature is too high, the water flow of the fresh air unit heater is very low due to the eagerness to reduce the temperature. At this timeIf the outdoor temperature is lower than 0 ° C, a heater frozen cracking accident is prone to occur.The accident shows that the buildings self -control software in the building is not perfect. The water flow control during artificial control is disconnected from the self -control anti -freezing protection device of the freshwake unit, so that the water flow of the fresh air unit can be reduced arbitrarily, leaving hidden safety hazards.At the same time, the operator also lacks experience in the safe operation of the new wind and air -conditioning units. It only pays attention to indoor temperature control and is small due to small loss.
The above four reasons for the frozen cracking accident of fresh air crew are all negligence in construction, commissioning, and runtime, which should attract the attention of relevant personnel.It is recommended to use a fan, circulating pump and electric heating valve lock to add facilities such as electric heater, duty fan to prevent the fresh air unit heater from freezing and cracking, and improve the technical measures for the safe operation of fresh air units in winter.In addition, if there is no connection air duct and electric insulation air valve between the fresh air unit and the new wind window, the anti -freezing range should be expanded to the entire new fan room.Electricity with heat, a fresh air unit with spray humidification should try to put water in the drainage water seal after being discontinued.