maintenance of fan coil unit

maintenance of fan coil unit  - What is the fan coil 

Central air-conditioning fan coil is ideal for end products, from heat exchangers, pipes, filters, fans, drain pan, exhaust valve, such as a stent, and its working principle is continuously recirculated air inside the room where the unit, passing air through the cold water (hot water) after the cooling coil (heating) to maintain the room temperature constant. Typically, a new air handling units after fresh air into the room to meet the needs of fresh air through the air-conditioned room. Mainly by the low noise motor, heat exchanger coil fins and other components.

maintenance note of fan coil unit.

1. fan. Fan is one of the main components of fan coil air conditioner, and it plays a role in air transport. At the same time, it is the driving force caused by the coil forced convection heat transfer, increase the heat transfer capacity. At present, the fan coil used in multiple leaf blower and centrifugal fan cross flow fan two types.

2. coil. It is a heat exchanger coil, fan coil units is an important component. Today, they use aluminum brass strings, by mechanical pipe up to eliminate the thermal contact resistance. There is also flaked tube production, usually for two or three rows of calandria tubes.

3. The blower motor. Usually capacitive circuits and oil-bearing, usually without refueling. Note that, if not oil-bearing should be regularly refuel. Typically it has a third gear shift to adjust the air flow, air volume control range of about 50%.

exposed type universal fan coil unit

4. box. Flush-mounted box is usually made from galvanized iron. Surface mounted to the tank surface spray paint or plastic, iron go through before spraying acid, phosphate and other treatment. Inside the box must have good insulation measures, the unit running when wet condition, can maintain good insulation effect, in order to avoid condensation enclosure.

5. high static pressure units. When assembling holes, seams, water tray, cooler and brass plate junction leakage problem is serious, some units at high static pressure, air leakage amounted to 20%, the proposed manufacturer in the assembly when , pay attention to sealing problems of the unit.

We need instantly check the fan coil units in order to ensure the effectiveness and lifetime use of air conditioning, fan coil when there is a problem to be repaired in time, bearing in mind the above considerations unit. This ensures that the fan coil repair if successful, be careful because communication professionals in the repair.

Bright Best air conditioning is a chinese private group of companies established in 2012 and specialised in climate technology.Which it has expanded over the years to a wide spectrum of products and services for air conditioning,treatment and ventilation,as well as heating systems for both industrial and domestics sectors.

Brightbest own the wide products include fan coil unit,brass ball valve,corrugated tube ,air conditioning thermostat and air curtains manufacturers.

Brightbest is provided with quality certification according to ISO9001:2000 and ISO14001:2004 and is strongly committed to customer satisfaction.

Brightbest is commited to a point of reference for energy saving and environmental protection technologies in the frame of international directives.

Basic maintenance of valves

1. The valve should be kept dry and ventilated room, both ends of the access to be blocked.

2. Long-term storage of the valve should be checked regularly to remove dirt and machining surface coated with anti-rust oil.

3. After installation, periodic inspection, the main test items:

(1) sealing surface wear. (2) stem and stem nut trapezoidal thread wear. (3) packing Obsolescence failure, should be replaced if damaged (4) valve repair assembly, the sealing performance test should be carried out

Before production and post-production of professional valve maintenance work prior to welding, the valve service in manufacturing operations plays a vital role in the proper and orderly and effective maintenance will protect the valve, the valve to function properly and to extend the use of the valve life. Valve maintenance work may seem simple, it is not. Work often neglected aspect.

1, the valve greasing, the grease quantity is often overlooked problem. After greasing refueling, the operator selects the valve and coupling greasing the way, were greasing operation. There are two cases: one injection insufficient greasing less grease, sealing surface due to lack of lubricant accelerate wear. On the other hand excess grease, resulting in waste. That there is no regulator valve according to the type of category for different valve sealing capacity for precise calculations. Can be calculated valve size and sealing capacity category, and then injected into a reasonable amount of grease.

2, valve grease, often ignore the problem of pressure. In operation grease, grease pressure regularly showed peak changes. Pressure is too low, seal leakage or failure, the pressure is too high, the grease port plug, sealed lipid hardening or seal with the valve ball, valve plate locking. Typically grease pressure is too low, the grease inject more into the bottom of the valve chamber, generally occurs in a small gate. The grease pressure is too high, on the one hand to check the grease mouth, hole blocking ascertain the situation in the case fat replacement; on the other hand is a lipid hardening, to use cleaning fluid, repeated failure to soften the seal fat, and inject new grease replacement . In addition, the seal type and sealing materials, also affected the grease pressure, different forms have different sealing resin injection pressure, in general, hard seal grease pressure is higher than the soft seal.

3，the valve greasing, note the position switch valve in question. When valve maintenance is generally in the open position state, choose to close maintenance under special circumstances. Other valves in the open position can not always be punished. Gate when conservation must be turned off to ensure full of grease along the ring seal grooves, if the open position, sealing grease directly fall into the flow channel or valve chamber, resulting in waste.

4, the valve grease, often ignore the grease performance issues. Operating pressure grease, grease, switch position are normal. However, to ensure that the valve greasing effect, and sometimes need to open or close the valve, for lubrication check to make sure the valve ball or gate valve surface lubricity evenly.

5, grease, pay attention to body drain plugs and pressure relief problems. After the pressure test valve, the valve chamber sealed chamber gas and water due to environmental temperature and boost, to conduct the sewage grease relief when, in order to facilitate the smooth progress of grease injection work. After greasing air and moisture sealed chamber is sufficiently displace. Timely vent valve cavity pressure off, but also to protect the use of safety valves. After greasing, be sure to tighten the wire blocking the sewage and pressure relief, to prevent accidents.

6, grease, pay attention to the problem of fat evenly. Normal grease from grease port hole nearest the fat out of fat first, and then to a low point, and finally the high point, successive out fat. If you do not follow the law or no fat, prove the existence of plug, clean through timely treatment.

7, we must observe the valve size and seat ring flush problems greasing. Such as ball valves, open position if there is interference, can be adjusted to the stopper in the open position, the lock confirmation straight path. Adjust the limit should not only seek one position on or off, to consider the overall. If the open position flush, customs are not in place, it will cause the valve closed lax. Similarly, adjust the clearance in place, but also consider open position accordingly. Ensure the right angle valve stroke.

brass air vent valve-705/release valve

8, after greasing, some seal grease port. Avoid impurities entering, or greasing mouth lipid oxidation, capping to apply anti-rust grease to avoid rusting. To apply when the next operation.

9, grease, it should also be considered in the future delivery of oil in order to treat specific issues. In view of the different quality of gasoline and diesel should be considered erosion and decomposition gasoline. When the valve after the operation, encountered gas segment operations, replenish grease to prevent wear from happening.

10, grease, do not ignore the stem portion of greasing. Sliding sleeve valve shaft portion or filler, and the need to maintain lubrication to reduce friction during operation, if they can not ensure the torque increase lubrication and wear parts, the electric operation, switch laborious manual operation.

11, some marked with an arrow on the valve body, if not accompanied by an English FIOW writing, for the sealing seat role in the direction, not as a reference medium flow, since the vent valve in the opposite direction. Typically, two-seater with two-way flow valve seal.

12, valve maintenance, and also pay attention to the electric actuator head in water issues. Especially in the rainy season, rainwater infiltration. First, make the actuator shaft sleeve or rust, and second, the winter freeze. When the electric valve operating torque causing excessive damage to transmission components cause the motor torque load or super jump can not be achieved to protect electric operation. Damage to transmission parts, can not be performed manually. After the super torque protection action, it is also unable to manually switch, such as the forced operation, damage to the internal parts alloy.

To sum up, the valve maintenance To correct attitude in order to achieve the purpose of the valve maintenance and application of the desired effect.

How to choose and buy Valve？

Select valve size

You must select consistent connection pipe and valve nominal diameter.

Valve materials.

In choosing the correct valve material, the following factors should be considered:

· Valve to be controlled fluid medium.

· Fluid medium temperature range.

. The valve will be subjected to pressure range.

· Weather conditions that may affect the operation of the valve.

.  The valve will be subjected to, possible extraordinary stresses.

· To meet the safety standards or pipeline regulations.

Purchase valve

When ordering valves, please provide the following information to avoid unnecessary delays and to ensure that the valve was indeed purchased valve they need.

1. Valve size.

2. Pressure interface materials: castings and components.

3. Valve Type: valve, stop valves, check valves, butterfly valves, ball valves, and so on.

4. Terminal connection, if the connection for the welding, but also to provide a connection pipe wall thickness; if the connection is a flange, to provide flange surfaces or finishes.

5. Any deviations from standard materials: sealing materials, bolting materials, and so on.

6. Any accessories: acid shield, locking devices, chain operation, and so on.

Brass top value/globe valve-307

Bright Best air conditioning is a chinese private group of companies established in 2012 and specialised in climate technology.Which it has expanded over the years to a wide spectrum of products and services for air conditioning,treatment and ventilation,as well as heating systems for both industrial and domestics sectors.

Brightbest own the wide products include fan coil unit,brass ball valve,corrugated tube ,air conditioning thermostat and air curtains manufacturers.

Brightbest is provided with quality certification according to ISO9001:2000 and ISO14001:2004 and is strongly committed to customer satisfaction.

Brightbest is commited to a point of reference for energy saving and environmental protection technologies in the frame of international directives.

Central air conditioning condenser cleaning procedures and precautions

Central air conditioning condenser can easily scale, the normal cooling in the summer of treatment should be done daily, otherwise it runs in an environment of high hardness, dissolved in water in the circulating water system inorganic salt will crystallize as the temperature rises precipitated the formation of scale on the wall of the condenser heat transfer surface, resulting in reduced heat exchange efficiency. At the same time hard scale is increased, the increase in energy consumption will increase when the hard knot scale 1mm thick 6 to 10. As the water soil, sediment, soil humus formation, with bacteria, algae and other microorganisms and the formation of secretions biological slime, will be attached to the condenser heat transfer tubes formed on the walls dirt, causing severe pipeline clogging; and dirt, slime will affect the heat exchange efficiency, more power can cause high voltage operation, causing severe overpressure shutdown . All this has seriously affected the normal operation of the condenser. Condenser cleaning is divided into physical cleaning and chemical cleaning, general physical cleaning with high pressure water jet condenser brass dirt cleaned out; if scaling a hard scale, should be carried out chemical cleaning, the scale can not be physically removed.

In order to optimize the condenser run in the state, it must condenser specialized chemical drug treatment, removal of scale, rust, slime, antiseptic and anti-corrosion treatment, reduced to clean metal surfaces.

Operating procedures:
(1) Close the valve out of the water, open the drain valve, check valve is closed and out of the case.
(2) Open the condenser cover, take a little scale on the brass surface with descaling agent do different concentration ratio of cleaning tests.
(3) The method by low prices, connected properly cleaning pump.

(4) the use of an external pump, to the bucket filled with water, start the cleaning pump cycle to smooth water.
(5) several times to slow the bucket plus YX-22 detergents. After repeated washing with tap water cycle to PH value to about 7.
(6) rinsed with tap water cleaning pump.
(7) Open the cover using Yaxin automatic machine guns pass through gun.

First, the physical cleaning

1.1 host physical gun suitable for water walking through the sediment and rust clogging the tube more serious equipment, such as a severe blockage before chemical cleaning equipment must first pass a physical gun.
1.2 Close out of the water valve, open the drain valve, check valve is closed out, the water will drain and clean the heat exchanger.
1.3 Opening the need to clean up parts of the cap, taking pictures, taking dirt samples for analysis.
1.4 The use of brass Yaxin through automatic machine guns, water cannons, and other tools to clear the rod clean.
1.5 Water indoor dirt floor clean, anti-rust paint brush, paint dry, take pictures.
1.6 test standard brass without clogging silt cleaning rate of 95%
1.7 open site restoration, pressure test watertight.

Second, chemical cleaning
The method uses a single professional cleaning cycle, using efficient detergents for Copper Tube ten times lower than that of an inorganic acid, based on the effective protection of equipment on the fast cleaning, descaling. After washing of brass pre-film treatment, can greatly slow down the corrosion rate of the device.

Bright Best air conditioning is a chinese private group of companies established in 2012 and specialised in climate technology.Which it has expanded over the years to a wide spectrum of products and services for air conditioning,treatment and ventilation,as well as heating systems for both industrial and domestics sectors.

Brightbest own the wide products include fan coil unit,brass ball valve,corrugated tube ,air conditioning thermostat and air curtains manufacturers.

Brightbest is provided with quality certification according to ISO9001:2000 and ISO14001:2004 and is strongly committed to customer satisfaction.

Brightbest is commited to a point of reference for energy saving and environmental protection technologies in the frame of international directives.

Fan Coil unit Selection FAQ

The effect of the use air conditioning, mainly due part in the design selection, and although the regular fan coil air conditioning system is different, but it is also a selection of certain ways, then the fan coil selection we will plant what the problem happen?

First, according to the cooling load selection drawbacks

According to the maximum cooling load of the room air conditioning fan coil unit air conditioning system design chosen common practice, its purpose is to ensure peak load when the room temperature. The air-conditioned rooms actually run most of the time will not be in peak load, so that the excess cooling capacity, switching to low-grade run to reduce the cooling output, thereby maintaining the heat balance of the room. Visible actual output capacity chillers depends on the air conditioning load changes, the nominal cooling capacity of the unit has little relationship. Therefore, the amount of cooling air conditioning is to achieve a necessary condition but not determine the effect of the use of air conditioning. Evaluation of the effect of bad air conditioning, one close to the average degree of room temperature and set temperature; second temperature distribution (gradient) and variations (fluctuations) amplitude. The larger the temperature difference between the air, the fewer the number of ventilators, temperature gradient and the greater the volatility, so the supply air temperature and air conditioning ventilation frequency accuracy and comfort is the main factor influence.

The higher the precision air conditioning required supply air temperature difference is smaller, the more the number of ventilators. Seen by the maximum cooling load selection, only to meet the peak load when the room temperature is not enough, need to meet the appropriate supply air temperature and ventilation rate, in order to ensure comfort requirements of the room.

Second, we can not guarantee a sufficient air supply

Due to air temperature, ventilation rate is to determine the accuracy and air-conditioned comfort of the main factors, it is to ensure adequate air flow to achieve the desired air conditioning effect is a prerequisite. Here, the amount of wind is the actual air supply unit when using it, rather than the catalog nominal amount of wind (GB / T 19232-2003 requirements: nominal air flow in the coil to be unreasonable water, air 14-27 ℃, fan speed high-end, low static pressure on the export of hydrostatic unit without air and filters to 12Pa measured airflow value). The actual use, the dark because they have to add the group installed, return air grilles, filters and short duct, coupled with the effect of water condensate coil surface, dust, clogging of the filter and many other factors, will lead to increased wind resistance, wind decreased, so that the actual air volume is far less than the nominal amount of wind (author through a lot of experiments to prove: Usually low l5-25%). Since the air volume significantly reduced, influence the effect of air-conditioning, mainly following problems:

1) ventilation fewer;
2) low air velocity, air impact jet range;
3) The air temperature is low, the impact of air-conditioned comfort and may cause air grilles or condensation.

On the other hand, for the fan coil unit itself, decrease the amount of air directly affects the heat transfer coil so that the coil cooling capacity decreased, which would form the actual performance of the unit (air flow, cooling capacity) is lower in nominal value of the anomaly. Thus, the nominal amount of wind, cold catalog on selection only as a reference when, and not as a basis for selection. Increase the amount of wind can not only increase the number of ventilators, reduce air temperature, improve air-conditioning effect, but also because the cold will increase correspondingly reduced in volume units. Therefore, to improve the air flow is one of the development direction of the fan coil. Of course, the air volume increase also conditioned by the area allowed wind speed constraints.

To control the supply air temperature difference between the cold air flow and should maintain proper matching relation. Full cooling capacity and air flow (mass flow rate) ratio is the difference between the enthalpy of the air coil import and export, which determines the cooling capacity of the supply air temperature and the size of the unit. From the perspective of controlling supply air temperature, enthalpy difference too negative, while domestic fan coil enthalpy difference and supply air temperature is generally high. Nominal parameters GB / T 19232-2003 shall be calculated enthalpy difference 15.88kJ / kg, supply air temperature of about l2 ℃. In terms of air volume decreased by 20%, the actual enthalpy difference will exceed 19.85kJ / kg, the actual supply air temperature will be up to l5 ℃, clearly beyond the predetermined permissible supply air temperature difference (6-lO ℃), it can not guarantee air conditioning precision and comfort requirements.


Third, ignoring the wind resistance calculation system

General fan coil air-conditioning system, air system a smaller scale, a simple structure, small resistance, within about l5-5OPa range, but this alone is enough to have a crucial resistance on the actual air supply fan coil system Impact. Fan coil units divided into low static pressure and high static pressure units into two categories, the GB / T 19232-2003, for the low static pressure units, with exports of static pressure and air filters, as OPa, and without air filter and other export static pressure 12Pa, that is, air filters, etc. and is composed of resistance 12Pa. US Air Conditioning & Refrigeration Institute standard "room fan coil air conditioner" hRI 440-84 clearly states: the factory without delivery, return air grille or filter fan coil should be under 12.4Pa external static pressure test wind u. Precisely in order to ensure that the actual air volume and the nominal amount of wind matches this provision. The high dust content of the atmosphere, filter clogging Netease, should external static pressure than 12.4Pa high contrast, China's industry standard test conditions specified in rationality open to question. Horizontal concealed in rooms, ceiling air return FCU, for example, additional resistance should at least include return air grilles, return air filters, air supply and air supply grille short tube resistance. If the return air wind speed 1.Om/s, air velocity of 1.5 m / s, this time outside the machine calculated resistance 16Pa, if the choice would certainly have caused low static pressure unit air volume decline, in this case in engineering applications should belong to smaller additional resistance example, and the amount of wind on like this, visible air system FCU additional resistance can not be ignored. Furthermore, for high static pressure units, if not through the resistance calculation, but that the choice of a high static pressure units can meet the requirements of the practice is unreasonable.

High static pressure duct fan coil unit

For example, a building within a horizontal ceiling installation concealed fan coil unit and the corresponding air system, the nominal amount of wind FCU is 750m / h, diffuser throat wind speed 2.5m / s, return air wind speed 1.5m / s, calculated FCU known outside the body of the total resistance of about 61Pa, wherein the diffuser, 80% of the return air filter resistance of the total resistance. In this case, even the use of external static pressure 30Pa machine or 50Pa High static pressure type FCU, air volume will decline about 15%. Thus, in the specific projects proposed in general terms as long as the high static pressure requirements and high static pressure unit does not have to be related air system analysis approach it is not desirable.

what are fan coil units ?

 (FCU) fan coil unit  is a simple device consisting of a heating or cooling coil and fan. It is part of an HVAC system found in residential, commercial, and industrial buildings. Typically a fan coil unit is not connected to ductwork, and is used to control the temperature in the space where it is installed, or serve multiple spaces. It is controlled either by a manual on/off switch or by thermostat.

It should be first appreciated that 'Fan Coil Unit' is a generic term that is applied to a range of products. Also, the term 'Fan Coil Unit' will mean different things to users, specifiers and installers in different countries and regions, particularly in relation to product size and output capability.


Fan coil unit are divided into two types: Two-pipe fan coil units or four-pipe fan coil unit. Two-pipe fan coil units have one (1) supply and one (1) return pipe. The supply pipe supplies either cold or hot water to the unit depending on the time of year. Four-pipe fan coil units have two (2) supply pipes and two (2) return pipes. This allows either hot or cold water to enter the unit at any given time. Since it is often necessary to heat and cool different areas of a building at the same time, due to differences in internal heat loss or heat gains, the four-pipe fan coil unit is most commonly used.

 4-way cassette fan coil unit(4 tube systerm)

Bright Best air conditioning is a chinese private group of companies established in 2012 and specialised in climate technology.Which it has expanded over the years to a wide spectrum of products and services for air conditioning,treatment and ventilation,as well as heating systems for both industrial and domestics sectors.

Brightbest own the wide products include fan coil unit,brass ball valve,corrugated tube ,air conditioning thermostat and air curtains manufacturers.

Brightbest is provided with quality certification according to ISO9001:2000 and ISO14001:2004 and is strongly committed to customer satisfaction.

Brightbest is commited to a point of reference for energy saving and environmental protection technologies in the frame of international directives.