The choice of an air conditioner
is not always very simple, and it is easy to get lost in a bewildering plethora of models with different specifications. Leaving aside the different characteristics, let us analyse a particular type of air conditioner found on the market, for its particular features: dual split, split trial, or, in general, the multi split models.
This type of product arose specifically to be used in offices, shops
and in general in an environment in which all the internal units are used simultaneously so as to fully exploit its performance.
at home, even when feasible, is not congenial for several reasons. Before addressing the why not, let's see why many people are oriented towards this product.
Basically there are two reasons that lead consumers to favour a multi-split model, these being the notion of saving on the purchase price and the idea of installing only one motor, which would gain space outside the house whilst achieving the same performance. We have used the term “idea” since the reality of things is different than the thought that in most cases has become installed in people’s minds.
First of all, the cost of a dual-split air conditioner in relation to two mono-split machines, of the same brand and characteristics, is in most cases higher and not only by a small amount, the same is true for the triple-split and other multi-split air conditioners. Hence the first idea, regarding the cost savings, falls through.
Looking in detail at the operation and components, it is necessary to know some basic aspects in order to correctly evaluate the second idea. The motor size in a dual-split model is much larger than the motor in a mono-split air conditioner, hence, once installed, a multi-split appliance, despite only having one motor on the outside, will occupy the space necessary for two, three or more air conditioners. In addition, with regard to the consumption there are differences, in fact, a multi-split has a higher overall energy consumption; this is clear not only if you use all the splits simultaneously, but even if you only turn one split (unit) on, you will have a minimal consumption level higher than that of a mono-split model with a higher nominal power rating.
The size of the appliance in this case becomes very important, because there is a fundamental aspect that needs to be understood. If we speak of a 9000 BTU/h mono-split air conditioner, this means in practice that the motor has the capacity to deliver the indicated power. Consequently installing it in an environment that requires this power will not cause any problems.
In the case of a multi-split appliance the situation is different, since the nominal power rating of the various splits does not correspond to the nominal power rating of the motor. To be practical, let’s use the example an air conditioner with three splits, and that needs to achieve a power of 9000 btu / h. The external (heat) pump in this type of combination, does not necessarily work at a power of 27000 BTU / h, but in all or in most cases operates at a power of 18000 BTU / h, consequently when you turn on the three splits simultaneously, the supply of air will be equal to 9000 btu / h (9000 x 3 = 27000) but the power will be distributed equally between the three units, which will deliver approximately 6000 btu / h each. The needs of an environment that requires 9000 Btu / h to be conditioned, will therefore not be met by the power delivered by this multi-split air conditioner. When buying an appliance, then, given that this "particularity" is often overlooked, it is imperative that the buyer should pause to ask and even better to check the specifications of the product, so as to avoid being in the position of having installed a system that fails to adequately cool and heat.
The installation of a multi-split air conditioner is much more expensive than the installation of an equivalent number of mono-split machines placed next to each other. With the multi-split you will only succeed in the best of cases to install two of the units shoulder to shoulder, while the other(s) will have to be placed in the distance between the motor and split(s). With this type of solution, the cost of assembling the appliance increases, due to the use of more pipes to reach the (various) splits. The motor is equipped with several terminals (or terminal blocks), each designed for connection of an indoor unit, and then a pipe for each machine that goes from an 'indoor unit to an outdoor unit, thus more manual labour and eventual amounts of refrigerant gas are thus required (increasing the overall cost of the installation).