two small vs one large unit

[souroull]

so i have a 38sqm room 3m high with 3 windows that i need to cool. i live in a humid (50-80%) and very hot (35-40deg) environment during the summer and i was wondering what the best option is when it comes to efficiency, two small (3.5kw) or one large (7kw) unit?

my options are as follows:

Toshiba RAS-10PKVP-E High Wall 2.50kw 5.26EER 3.00kW 5.36COP

Toshiba RAS-13PKVP-E High Wall 3.50kw 4.55EER 4.00kw 4.76COP

MHI SRK35ZJX-S High Wall 3.50KW 4.12EER 4.30KW 4.48COP

MHI SRK63ZK-S High Wall 6.30KW 3.58EER 7.10kw 3.97COP

MitsuE MSZ-GE71VA High Wall 7.10kw 3.33EER 8.10kw 3.83COP

MHI SRK71ZK-S High Wall 7.10kw 3.29EER 8.00kw 3.74COP


what would you choose based on the fact that i'm going to need heating for 2-3months and cooling for up to 6 months per year?

[souroull]

..... anyone?

also open to other unit recommendations but price vs efficiency is my priority

[install monkey]

38m2 room - how long,wide- cheaper to go for 1 big unit if a square room,as you only need 1 power supply and only need to fit 1 system

[Scramjetman]

Loaded question without seeing a heatload calculation.

Whatever combination that you put in, it has to do the job properly, so first, you at least need enough power to manage the maximum heat load. In addition, if you want lower operating costs, put in two smaller ones with higher efficiency numbers. If you want lower capital and installation cost, put in a single larger one that is less efficient.

The economic way, is to do a life cycle analysis. This means you add up the cost of the machine/s, maintenance costs (don't forget 2 x machines have more maintenance than 1) and estimate how much energy it/ they will consume in their usable life. Depending on where you are, the machine's life could be 5 - 8 years, for a wall hung split. Whichever combination comes out cheaper - then that's your selection.

[Nabil2010]

I think you should just get one large unit.

Hey, i have a question...my outdoor unit was stolen, so i got a different one...but this one is bigger and says r22 760g while the old one was r22 520g

do you think they are compatible?

[Scramjetman]

Nabil, a bit more detail is needed here. Sounds like the replacement has a larger charge and is therefore a larger machine.
Generally speaking, we are playing with fire when we mismatch indoor and outdoor units simply because if there are electronics involved, the manufacturers build in checking software to see if the units are correctly matched.
If the elctronics aren't an issue (ie: there is none) and the outdoor unit is oversized, the compressor will tend to run low suction temperatures. In an A/C application, this can mean subzero temperatures which will cause the evaporator to ice up and block the air flow. It's only a tiny step from this situation to a liquid floodback situation which will promptly dispatch your compressor to heaven with its internals in lots of tiny pieces.

[install monkey]

at least they'll struggle more when they nick this condenser!!

I think you should just get one large unit.

Hey, i have a question...my outdoor unit was stolen, so i got a different one...but this one is bigger and says r22 760g while the old one was r22 520g

do you think they are compatible?

[Scramjetman]

The bad guys just get smarter and come with more bad guys, cranes and stuff and nick the bigger machines too... It's no wonder we drink!