What water parameters should be confirmed before connecting the air conditioning box to the cold water system?

Before connecting the air-conditioning box to the cold water system, the supply and return water temperature, available flow rate, operating pressure, available pressure difference, water quality and interface form should be confirmed. The pressure that the coil can withstand and the pressure difference that can be provided on site are two different things, and the size of the connection port cannot replace the complete water system conditions.

Verify performance conditions separately from mechanical connections

The heat transfer calculation mainly depends on the water temperature and flow rate, while the coil material selection and connection also need to consider the medium composition, corrosiveness, design pressure and water treatment method. The site should indicate whether it contains ethylene glycol and other media and its concentration, and indicate whether the pressure value belongs to static pressure, pump operating pressure difference or design pressure requirements to avoid mixing concepts.

Heat exchange conditions include the design supply and return water temperature, flow rate and possible fluctuations throughout the year; operating conditions include pressure, pressure difference, medium, water quality and shutdown antifreeze arrangements; connection conditions include interface direction, flange or thread, valve parts and maintenance locations. The three types of conditions correspond to different majors and cannot be given just one interface size. How the coil water flow corresponds to the design cooling capacity can be referred toHow does the water flow rate of the air conditioning box coil correspond to the designed cooling capacity?。

The supply and return water temperature determines the heat exchange capacity

The supply and return water temperature is the core water-side parameter for coil selection. When the water temperature is on the high side, even if the water volume is increased or the number of rows is increased, the target outlet air moisture content may not be achieved; when the water temperature is on the low side, it is also necessary to check whether the coil surface temperature will lead to the risk of excessive condensation or frost. The relationship between the designed supply and return water temperature difference and flow rate needs to be checked together. If the temperature difference is too large or too small, it will affect the balance of the water system.

If the project uses high-temperature cold water or a large temperature difference system, the number of coil rows and headwind speed may need to be adjusted accordingly. How to select the type of surface cooler according to the air inlet and outlet conditions, please refer toHow to select the type of air conditioner cooler according to the air inlet and outlet conditions? ;The relationship between supply air dew point and water temperature can be referred toWhat role does the supply air dew point play in the selection of fresh air air conditioning boxes?。

The flow rate and pressure difference should correspond to the same working condition.

The available flow rate and available pressure differential need to be confirmed at the same time. Coil water resistance changes with flow, and the pressure differential that the on-site pump can provide must cover losses in the coil, valves, and pipelines. If only the flow rate is given but not the pressure difference, it is impossible to judge whether the water system can deliver water to the coil; if only the pressure difference is given but not the flow rate, it is impossible to judge whether the heat exchanger is sufficient.

Valve selection and line balancing also affect actual flow. Before connection, it should be confirmed which party provides the filtering, exhaust, sewage and balancing valves. The weight of the on-site pipelines cannot be borne by the coil joints. Water system information should be assigned to interface responsibilities to avoid omissions between equipment manufacturing and on-site takeover.

Operating pressure, water quality and media should be checked individually

The pressure that the coil can withstand and the on-site operating pressure are two different things. The design pressure, operating static pressure and pump outlet pressure difference should be noted to avoid confusing different concepts. In terms of water quality, attention needs to be paid to hardness, chloride ions, suspended solids and corrosiveness. Mismatched water quality may affect coil life and heat transfer effect.

When containing antifreeze media such as ethylene glycol, the density and specific heat are different, and the water volume conversion cannot directly use the coefficient of ordinary water. Arrangements for shutdown and antifreeze should also be stated in advance, especially for coils outdoors or in unheated computer rooms. When the water quality and medium conditions are unclear, the coil material selection and interface form can only be tentatively determined.

The interface form and maintenance space must be confirmed simultaneously

The interface direction, flange or thread form, pipe diameter and valve position need to correspond to the on-site pipeline layout. Coil joints cannot bear the weight of the pipeline, and independent supports should be provided on site. The maintenance space must be able to accommodate valve operation, filter cleaning and coil inspection, and cannot wait until the equipment is in place.

The interface size cannot directly determine the on-site pipe diameter. Please refer toCan the diameter of the water pipe in the air conditioning box be determined directly based on the coil interface? . The water tray and drainage conditions must also be checked simultaneously, please refer toHow to combine the slope of the water pan of the air-conditioning box with the layout of the drain outlet?。

Water system debugging conditions before connection

Before the cold water system is connected, the pipelines should be cleaned, exhausted and pressure tested, the valves and actuators should operate normally, and the filters should be installed in place. After filling the system with water, check the coils and connections for leaks before gradually putting it into operation. During the commissioning phase, the actual supply and return water temperature, flow rate and pressure difference should be recorded and compared with the design conditions.

If the actual water temperature or flow rate deviates from the design value, the air outlet status of the coil should be recalculated and compensation cannot be made by adjusting the valve opening alone. For the sequence of joint debugging of the water system and air conditioning box, please refer toHow to change the debugging sequence of air conditioning box from stand-alone unit to system linkage?。

Aili industrial supporting equipment

Aili Industrial's unit selection can be advanced based on the confirmed water side data; it is recommended to check the interface diagram and valve range together to reduce omissions between equipment manufacturing and on-site takeover. Aili Industrial can jointly check coils, water trays, drainage structures, fans, and control configurations; the manufacturing end covers independent R&D and production of motors and fans, control systems, sheet metal, air filters, and complete machine assembly. Coil water resistance, interface forms, and maintenance spaces can be aligned in the same package.

Product form can be viewedAir handling unit andFan box page; clean air supply package can be combinedFFU fan filter unit andHEPA/ULPA filter verification; when it comes to gaseous pollution control, you can communicate separatelyChemical filter solutions. The specific heat transfer effect, water side applicable conditions and delivery scope still need to be verified based on the corresponding configuration data and on-site working conditions. The actual effect is subject to on-site water system debugging and performance test results.

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Related questions and answers

Only the interface size is provided. Can cold water access confirmation be completed?
not enough. The supply and return water temperature, flow rate, pressure difference, operating pressure, water quality and medium conditions are also required. The interface size is only one of the connection conditions.

If the coil has enough pressure, does it mean that the on-site water system can definitely be used?
uncertain. The coil pressure bearing capacity is the equipment's endurance capability. The available pressure difference, flow rate and water quality also need to be checked on site. The two cannot replace each other.

Can Aili Industrial help check the cold water access conditions?
The water side conditions can be checked based on the coil configuration, water resistance and interface form. The specific plan needs to be confirmed based on the project water system data.

Related articles

1. How does the water flow rate of the air conditioning box coil correspond to the designed cooling capacity?

2. How to select the type of air conditioner cooler according to the air inlet and outlet conditions?

3. Can the diameter of the water pipe in the air conditioning box be determined directly based on the coil interface?

4. How to combine the slope of the water pan of the air-conditioning box with the layout of the drain outlet?

Key points for selection and acceptance inspection