How to distinguish the reasons between the water side and the air side when the air supply temperature of the air conditioning box cannot be lowered?

If the air supply temperature of the air conditioning box cannot be lowered, the air inlet and outlet status, air volume, cold water supply and return water temperature and valve status should be recorded at the same time, and then distinguish between insufficient cold source, water volume problem, air load change or heat exchange abnormality. Only one outlet air temperature is usually not enough to determine whether there is a problem with the coil itself.

First, put the actual working conditions side by side with the design working conditions.

If the inlet air is hotter and more humid than designed, or the air volume increases significantly, the air outlet from the original configuration may change; if the cold water temperature is too high, the target may not be achieved even if the valve is fully opened. The displayed opening of the valve cannot directly prove that the water volume is sufficient. It should be checked in conjunction with the pressure difference, exhaust and actual waterway status to avoid replacing components when there is insufficient evidence.

The air side should record the inlet temperature and humidity, actual air volume, bypass and coil cleaning status; the water side should record the supply and return water temperature, flow or pressure difference, exhaust and valve status; the control side should check the credibility of the measuring points, set values, instructions and actual actions. The three types of data correspond to different reasons, and you cannot just look at one outlet air temperature. 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?。

Troubleshoot measurement and control mode problems first

If the supply air temperature probe is located in a local cold or hot air flow, the reading may deviate from the cross-sectional average. If the control mode is in dehumidification, preheating, reheating or duty status, the supply air temperature setting and actual target may be different from conventional refrigeration. Before troubleshooting, you should confirm whether the measuring point location, set value, current mode and valve command are consistent.

How to avoid local airflow at the sensor location, please refer toHow should the air supply temperature sensor of the air conditioning box avoid the influence of local airflow? . For control point table and mode definition, please refer toWhat point tables need to be provided before the air-conditioning box is connected to the building automation system? . If the control screen shows that the valve is closed but it is not actually closed, or the instructions and feedback are inconsistent, the control problem should be dealt with first instead of directly judging that the coil heat exchange is insufficient.

How to check the causes of water side one by one

Common causes on the water side include high cold water supply temperature, insufficient water volume, valves that are not truly opened, pipeline air blockage, filter blockage, insufficient water pump head, and water quality that affects heat exchange. The temperature difference between supply and return water can assist in judgment: too large a temperature difference may indicate insufficient water, and too small a temperature difference may indicate problems with the heat exchange area or air side, but it needs to be looked at together with flow and load.

How to confirm the cold water parameters, please refer toWhat water parameters should be confirmed before connecting the air conditioning box to the cold water system? . For the relationship between coil water flow and design cooling capacity, please refer toHow does the water flow rate of the air conditioning box coil correspond to the designed cooling capacity? . When the medium contains ethylene glycol, the density and specific heat are different, and the ordinary water coefficient cannot be directly used for water volume conversion. Waterside inspection should be carried out by professionals according to the shutdown isolation process. It is not appropriate to disassemble components under pressure.

How to check air side causes item by item

Common causes on the air side include excessive air volume, higher inlet temperature and humidity than designed, reduced air volume due to clogged filters, dust accumulation on the coil surface, air flow bypass, uneven mixing, and reheat or humidification interference. When the air volume is too large, the contact time between the air and the coil is shortened, and the outlet air temperature may not drop; when the air volume is too small, although the contact time is increased, the total cooling capacity may be insufficient and the room temperature may still be too high.

For the influence of coil head-on wind speed on heat transfer and water entrainment, please refer toWhat impact does the coil head-on wind speed have on heat exchange and water entrainment in the air conditioning box? . For the relationship between coil row number and cooling capacity, please refer toWill the greater the number of coil rows in an air-conditioning box, the greater the cooling capacity? . To troubleshoot filter blockage and insufficient air volume, please refer toIf the total air volume of the air conditioning box is insufficient, should I check and measure it first or should I increase the speed first? andHow to troubleshoot if the air conditioner fan is running but there is no obvious air supply?。

Mixing, bypass and functional segment order also affect the air outlet

Insufficient length of the mixing section or changes in the proportion of new return air may cause the coil inlet state to deviate from the design. The bypass duct is not closed, the access door is leaking, or the filter section is bypassed, allowing some air to bypass the coil. If the reheating section or humidifying section is put in by mistake, the cooling effect will be offset. Functional segment order and mixing conditions should be checked together.

How to calculate the mixed air state, please refer toHow should the temperature and humidity of the mixed air in the air conditioning box be calculated? . For the influence of mixing section length, please refer toHow long is the air mixing distance required in the mixing section of the air conditioning box? . For the design basis of function segment sequence, please refer toOn what basis should the sequence of functional sections of the air conditioning box be determined? . To deal with air leakage in the bypass duct, please refer toHow does the chemical filter of the air conditioning box deal with air leakage from the bypass duct?。

How to organize an effective fault feedback

During stable operation, various data are recorded simultaneously, indicating the production load and outdoor conditions, and attaching the corresponding design table. If there are only historical instantaneous screenshots, time inconsistency may lead to misjudgment. Before checking the waterway or disassembling components, the on-site shutdown and isolation process should be followed; it is not appropriate to use unfounded large adjustments to cover up the cause.

Record content can include: supply air temperature setting and actual measurement, return air temperature and humidity, air volume or fan frequency, cold water supply and return water temperature and pressure difference, valve instructions and feedback, filter pressure difference, and current operating mode. For condition checks before starting the machine for the first time, please refer toWhat conditions need to be checked before the air conditioner is turned on for the first time? . How to change the debugging sequence from stand-alone to system linkage, 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 can cooperate with equipment verification based on the water and gas data at the same time to provide the original selection working conditions and on-site trends, which will help narrow the scope of investigation. Aili's industrial manufacturing end covers independent research and development and production of motors and fans, control systems, sheet metal, air filters and complete machine assembly. Coils, fans, control measuring points and box structures can be corresponded in the same set of supporting materials; non-standard coils and interfaces can be adjusted according to on-site water system conditions.

Product form can be viewedAir handling unit andFan box page; clean air supply package can be combinedFFU fan filter unit andEFU equipment end fan filter unit verification; terminal particle filtration can be combinedHEPA/ULPA filter confirmation; when it comes to gaseous pollution control, you can communicate separatelyChemical filter solution; multiple devices can be linked together to understandFFU computer group control system . Supporting method of The specific heat exchange effect, 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

The supply air temperature cannot be lowered. Should I check the water side or the air side first?
It is recommended to confirm the measurement, operating mode and actual status of the valve first, and then record the water side and air side data simultaneously. It is easy to miss the reason by checking one side alone first.

If the cold water valve is fully open, does it mean there is enough water?
uncertain. If the valve opening is not equal to the actual flow, the temperature difference, pressure difference, air blockage and filter status of the supply and return water must be checked.

Can Aili Industrial help troubleshoot the supply air temperature problem?
The original selection working conditions, water and gas side data and equipment configuration can be combined to help narrow the scope. The specific processing must be implemented by on-site professionals according to the equipment instructions.

Related articles

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

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

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

4. How should the air supply temperature sensor of the air conditioning box avoid the influence of local airflow?

Key points for selection and acceptance inspection