I have an 11 year old 'conventional' Mitsu 12000BTU air con in my bedroom, which takes in air at the ambient room temperature, cools it down to 16 degrees and pumps it out until the ambient temperature is down to whatever I have set on my remote control, at which point the compressor should stop.
This past month this has not happened and so the unit has been on for 6 hours a night, 18.00 to midnight, consuming approx. 1 kW of electricity per hour.
After reading several posts here with members saying that an Inverter type had cut their lekky consumption by 50%, I am thinking about replacing it with say, a Mitsu 12500 BTU Happy Inverter @ Bht 18000.
So going through the figures, 6 hours per day x 30 days per month = 180 units, @ Bht 5 per unit = Bht 900. 50% saving = Bht 450. ( I know it MAY go back to Bht 4)
This would not be every month as some I do not put it on at all, but let's say 8 months per year = Bht 3600 saving per year.
The cost of the Inverter is Bht 18000 divided by the annual saving of Bht 3600 = 5 years before any savings seen.
Can anyone see a flaw in my O Level maths?