- Air conditioning systems – step by step
- One outdoor unit for several indoor
- Multisplit characteristics
- Choosing a multisplit
- Features of installing multisplit air conditioners
In this Article: History of Multisplit Creation; their difference from conventional split systems; pros and cons of multisplits; climatic systems with one and several compressors; multi-unit air conditioner – compare and choose; what to consider when installing a multisplit.
Whatever one may say, but one air conditioner is not enough for the whole apartment and you will have to spend money on several splits, which is not cheap. However, you can buy a device of the “columnist” class – its power will be quite enough, provided that the rooms are connected to each other like a gallery, and the cold air flows do not interfere with households. On the other hand, there are multisplits, some models of which are capable not only of cooling the atmosphere in all rooms of the house, but also of heating and cooling rooms at the same time. Let’s figure out what multisplit air conditioners are.
Air conditioning systems – step by step
Before moving on to the study of multisplits, I suggest recalling the previous materials from this series. So, we learned about the purpose of creating air conditioners and their types, got acquainted with the installations of semi-industrial and industrial use, capable of serving buildings of a thousand-meter area. An article about window air conditioners debunked the opinion about the complete disappearance of monoblock devices – it turns out that window frames even surpass modern splits in some characteristics. For townspeople who often change a city apartment for a country cottage, a mobile air conditioner is ideal – it is easier and cheaper to purchase a mobile monoblock than to separately purchase air conditioning units for an apartment and a summer cottage. Yes, and some dark personalities can easily steal a split from a dacha, despite its defensive structures.
Such familiar and seemingly well-known split systems turned out to be not at all simple – behind the brand, series and price there is more hidden than the natural desire of manufacturers to extract maximum income. It’s simple – if you want the split to supply only cold air, then get a cheap model, but if you need a really comfortable atmosphere in the house, then only cold air will not be enough here.
We continue to publish materials about climate technology – let’s talk about multisplits and find out what kind of air conditioners are they.
One outdoor unit for several indoor
In the early 30s of the last century, the division of a household air conditioning system into two units was not just a quirk of inventors, but a necessity – poisonous ammonia was used as a refrigerant in those years, the leakage of which was inadmissible. With the discovery of a new type of refrigerant – freon – the situation changed, since it was safe for humans. Household air conditioners have become monoblock, intended for installation in window openings. Years later, Japanese manufacturers of air conditioners again returned to the design of two blocks – Toshiba developed the first split systems, and Daikin went further, creating in 1969 a household climatic device from one external and two indoor units, called multisplit.
The domestic version of multi-zone air conditioning systems – multi-unit air conditioners – are used to regulate climatic conditions in large rooms separated by airtight partitions. Since there is only one external block, then the characteristic for our time the curtain of building facades with dozens of blocks from split systems does not occur, i.e. the original architectural appearance of buildings remains unchanged.
Multisplits are produced in two design solutions – with one and several compressors. The number of indoor units for models with one compressor is limited only by the compressor capacity, i.e. the total power of the hair dryers should not exceed the power of the outdoor unit (ideally, the compressor power should be about 15–20% higher). Buyers are offered multisplits of this type with a standard set of indoor units, or future owners of a split system can separately purchase an external unit, and then select the required number of internal hair dryers for it. Systems with several compressors in an outdoor unit (no more than 3) are designed to operate with a limited number of indoor units equal to the number of compressors – one compressor for one hairdryer. The difference between multisplits with one and several compressors is that indoor units in air conditioning units of the first type are capable of operating only in the same mode – either cooling or heating, and the hair dryers of multi-compressor air conditioners operate in independent modes.
Air conditioning systems of this type are equipped with conventional and inverter compressors, indoor units can be either wall-mounted or ceiling-mounted, floor-standing, cassette or ducted. The general principle of operation of multisplits is identical to that of other classes of air conditioners. Models equipped with an inverter compressor have a certain advantage in terms of energy saving – the electronic control system is able to extract heat or cold from empty rooms served by a multisplit, transporting them to rooms with increased load on the climate system. For example, if in the summer several people gather in the hall of the house, the multisplit will take the cold from other rooms (bedrooms, children’s rooms, etc.), the climate in which has been brought to a user-specified level. During the installation of the outdoor unit, one direction of the refrigerant line is set as a priority – this room will be serviced by the climatic device with particular care. Usually this is a room with the largest number of working equipment (for example, a server room) or the constant presence of a significant number of people.
Air conditioning multisystems are ideal for installation in buildings related to the number of cultural monuments and houses, the architectural design of which does not allow equipping the interior with conventional splits – the outdoor unit can be placed outside the facade, for example, on the roof. Regardless of the installation location of the outdoor unit, significant space savings are achieved, because for two-unit split systems, more of it will be needed – multiple of the number of indoor units.
Reducing the number of outdoor units to one reduces the cost of maintaining the climate system – refueling, cleaning, preventive maintenance, etc..
The user gets more freedom in terms of choosing the power of the indoor hairdryer for each served room, depending on its area, the number of people constantly present and the number of operating equipment.
The power supply needs to be pulled to only one external unit – the internal units of the multisplit receive electricity through the cable from the compressor unit.
Inverter multisplits are more economical than two-unit split systems with inverter compressor.
Let’s move on to negative characteristics. The first minus of multi-unit splits is that in the event of a breakdown of units in an external unit, the air conditioning system will fail completely.
All multisplits are more expensive than the models with one external and one internal unit corresponding to them in terms of power. At first glance, this looks strange, since there is only one external unit – the higher price is explained by the fact that the installation of such an air conditioning system is more difficult to perform, taking into account the several times longer refrigerant route, a complex circuit of channels for condensate drainage and a significant mass of the external unit (over 50 kg). Multisplits are equipped with a more complex control system, which is responsible for the temperature regimes in each of the serviced premises separately, which requires precise adjustment of the compressor and ventilation unit operation. Also, the prices for equipment of this class are regulated by the manufacturers themselves, who prefer to maintain prices at a high level to give it a greater status..
Taking into account the high power of the compressor, the external unit of the multisplit produces more noise during operation than a conventional split.
Choosing a multisplit
I propose to investigate the characteristics of external blocks, which will not be easy for the buyer to choose – first you need to choose them, and select internal hair dryers after. The comparative review will include outdoor units from multisystems from popular Japanese manufacturers Mitsubishi Electric, Daikin and Toshiba, with equal cooling capacity.
|specifications||MXZ-2C52VA, Mitsubishi Electric||3MXS52E, Daikin||RAS-M18GAV-E, GAV series, Toshiba|
|power supply and power consumption|
|power consumption for cooling, kW||1.3||1.5||1.5|
|power consumption for heating, kW||1.6||1.7||1.8|
|energy efficiency ratio EER||3.83||3.46||3.25|
|maximum serviced area, m2||50||50||50|
|temperature range for cooling, ° С||from +10 to +43||from +10 to +46||from +15 to +43|
|temperature range for heating, ° С||up to 15||up to 15||up to 15|
|cold performance, kW||5.2||5.2||5.2|
|heat capacity, kW||6.4||6.8||6,7|
|noise level of the outdoor unit min / max, dB||46/49||46/47||49/51|
|operating modes, name *||cooling, heating||cooling, heating||cooling, heating|
|type of shell||horizontal monoblock||horizontal monoblock||horizontal monoblock|
|body material||metal, plastic||metal, plastic||metal, plastic|
|type of instalation||floor (roof), wall (on the mounting frame)||floor (roof), wall (on the mounting frame)||floor (roof), wall (on the mounting frame)|
|type of refrigerant||R410A||R410A||R410A|
|maximum length of the freon line for one block, m||thirty||25||20|
|maximum height difference between outdoor and outdoor units, m||20||15||ten|
|maximum height difference between indoor blocks, m||not installed||7.5||not installed|
|maximum number of indoor units, pcs. **||2||3||2|
|anti-corrosion protection of the housing from the inside||+||+||+|
|the ability to work at any time of the year||+||+||+|
|mounting kit for outdoor unit||additional option||additional option||additional option|
|size of the external block HxWxD, cm||55x80x28.5||73.5×93.6×30||55x78x29|
|outdoor unit weight, kg||52||49||40|
|brand owner||Mitsubishi Electric Corporation, Japan||Daikin Industries Ltd, Japan||Toshiba Corporation, Japan|
|country of origin||Thailand||Thailand||Thailand|
|estimated service life, years||ten||ten||ten|
|average cost, rub.|
(*) – the external unit of any split system participates in the cooling or heating of the refrigerant, the ventilation and dehumidification functions are performed by the internal unit (s);
(**) – usually blocks-hair dryers are selected for the outdoor multisplit block at the rate of one block for one room. The capacity of each indoor unit is determined by the size of the served room, its location is determined from the interior features of the room.
MXZ-2C52VA, Mitsubishi Electric
Let’s analyze the collected information on the external blocks of multisplits:
- Among the models under consideration, the Mitsubishi unit has the highest energy efficiency, i.e. its efficiency is higher than that of the other two;
- the Mitsubishi block weighs more than the other two – it must be installed on a solid base (hollow bricks will not work). The Toshiba model weighs almost 10 kg less than others, therefore, less requirements are imposed on its mounting base;
- a Mitsubishi device allows you to stretch the longest pipeline to it without additional refrigerant injection;
- all three models are manufactured in Thailand, have the same warranty period and will last approximately the same period;
- the blocks in question are produced by the largest manufacturers of climate technology in the world;
- all units are equipped with inverter compressors that ensure efficient operation of the air conditioning system in heat pump mode;
- only a Daikin brand unit can connect more than two indoor units to it. As a result, the climate system, composed of three internal hair dryers, will create a favorable atmosphere in three rooms isolated from each other at once;
- the lowest cost is an external unit of the Toshiba brand.
Conclusion: according to the results of the analysis, it is not possible to unambiguously recognize one of the three considered models as the best, since each of them has unique pros and cons – the Mitsubishi unit consumes the least amount of electricity, the Daikin device is able to work with three indoor units at the same time, and the Toshiba external unit is cheaper others, although inferior to them in a number of parameters. The final decision rests with the homeowner – what is more important to him, energy efficiency and productivity, the number of units in the multisplit system or the total cost of the air conditioner.
RAS-M18GAV-E, GAV series, Toshiba
Features of installing multisplit air conditioners
The first and most important task is to determine the location of the outdoor unit. Unlike split systems, the external blocks of multisplites must be set so that the length of the freon line leading from them to each indoor unit does not exceed the maximum allowable by the manufacturer, otherwise the quality of the climate system will seriously decrease.
It is best to install the external block on the roof of the building, so that it will not “decorate” the facade with itself, and it is much easier to carry out preventive maintenance with its reception after the work in this case. If the installation of the unit on the roof or facade is for some reason impossible (for example, due to the excess of the length of the freon line), then it is mounted in the attic, balcony or in a semi-basement room. However, placing the outdoor unit in a closed room is undesirable, since if there is insufficient ventilation, it will overheat, which will lead to frequent system shutdowns and increased wear of the units.
Now about the pipes and wires connecting the multisplit blocks to each other – installers invariably want to lead them along the facade of the building, closing the outside with an unattractive plastic box, since doing this is easier than pulling communications through the mines inside the building. In the case of a sufficient distance between the blocks, you should insist on the hidden installation of the highway, since it should not be under the influence of the changeable external atmosphere.
Regardless of the type of indoor unit you choose (wall-mounted, cassette, etc.), it is necessary at the stage of installing the multisplit to resolve the issue of draining condensate from the hair dryer – ideally it should be discharged into the sewer system.
To solve the problem with air conditioning, multisplit systems are more suitable than others if:
- the rooms that are to be serviced by the climatic device are in the stage of rough repairs (i.e. without finishing the walls) – laying the freon line into the walls in this case will be cheaper;
- a balcony of sufficient area is located near the serviced premises, where an outdoor unit can be installed;
- the windows of the rooms where the internal blocks of the multisplit are supposed to be installed face one side of the house – in this case, the length of the pipeline will be the smallest and will not go beyond the standards set by the manufacturer.
Focusing only on the cost of the external multisplit unit will be incorrect – depending on the capacity, the number of functions performed and the manufacturer, the internal units will also cost a considerable amount (on average, the price of one hairdryer unit will be 25,000 rubles)..
From the next article you will learn about ceiling and floor split systems, their technical characteristics and functional features..