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Old 04-05-2016, 09:58 PM   #7326
ksrokiller
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Join Date: Nov 2007
Posts: 2,906
The calculator is a good easy tool, but it's based on a pretty huge usage pattern, probably a temperature set pretty low or the heat load is high. Heat load high can come from number of pax in the room, high number of electrical appliances, or the walls/floors suck in insulation. (I know some old resale units are really very lossy )


I just quote it and DIY some calculations, better to see it from another angle in terms of efficiency percentage which translates to kWh savings per month/year/7 years.


Panasonic CU-PS12NKZ 2 ticks.
Cooling capacity 4kW. Amps draw 4.2A

Panasonic CU-XS12RKZ 4 ticks
Cooling capacity same 4kW. Amps draw 3.7A

I didn't manage to find 5 ticks for Panasonics.
Both are inverters.

Difference = 13% in electrical consumption between 2 and 4 ticks

If your monthly aircon bill for this 12k FCU is $70 (4-ticks), then it's $79 for the 4-ticks, for the aircon component with a 13% difference. (that's a decent amt of usage - i use much less). Or 108 yearly. Or 756 for 7 years. That is one room with 12k btu/hr FCU (pretty powerful....maybe big MBR)



I use another model that's 9000 btu/hr and folks would be able to relate better with a 9k FCU.

Panasonic CU-XS9RKZ 4 ticks
3.4kW cooling. 2.7A. 840W full load.
(3.2kW cooling needs about 2.55A?)

Panasonic CU-PS9NKZ 2 ticks
3.2kW cooling. 3.3 amps

29% difference between 2 and 4 ticks in this scenario.


If your monthly aircon bill for this 1 room is $60 thereabouts for the 4-ticks, expect $77 for the 2 ticks 9k FCU. $204 diff per year, 1428 diff per 7 years.


How much is $60 worth of electricity? It is 0.1768/kWh now, add 7% gst and it's $0.1892/kWh. $60 is 317kWh, 4-ticks, or 317/30 = 10.56 kWh per day.
The 4-tick system just manages 840W full load, 8hrs usage is just 6.72kWh daily. 3.4kW cooling capacity, or 10,900 btu/hr system.
To get 10.56kWh daily usage so as to achieve that $60 electrical AC bill per room, the operation at full load non-stop would be 12.5 hrs daily



I do not think one can gun the darn 10,900 btu/hr aircon 12.5hrs @ full capacity in a BTO room without freezing to uncomfortable levels. ie set it at 16 deg C


In real life, the aircon usage, at least for me, is way lesser than what is shown by the .gov.sg calculator.
ie just go by percentages. Take a max of 30% (it could just be 13%. whatever). If your bill aircon bill is just $25 per room monthly and you have 2 rooms AC nightly, then it's a $50 AC bill montly.
30% diff is 15 dollars difference. It will be less if it's 13%
7 years = $1260 for these 2 aircon rooms.
(in my case, it's probably lower than even $1000 for 2 rooms over 7 years)

Not sure what is the price difference between the 4 or 5 and 2 ticks system though. But i guess it's less than $1,000 nowadays, last time it was way more i think. So i guess it still pays somewhat to go for the 4 or 5 ticks, all things being equal.
is Panasonic CU-XS9RKZ 4 ticks colder than the mitsubishi heavy industries SRK25ZMA 4 tick
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