I have Thermoline (copper tubing) catalogue with me. The safe working pressure claimed under Australian Standard AS1571-1985, for 6.4x0.58mm is 981psi, for 9.5x0.58mm is 639psi, for 12.7x0.58mm is 470psi.
When I check with MHI engineer their recommended test pressure for their R410a system is 400psi. Daikin told me 400 to 450 psi.
If you check the R410a properties at 34 deg C the gas or liquid pressure is only around 290psi. In order for the system to fail, unless someone heat the gas up to 54 deg C then the pressure shall reach 470psi.

That means if you use back R22 copper tubing for R410a up to 1.5hp you still have around 60% safety factor. Of course 60% might not be comfortable if you consider others factors.

That's why I said 1hp should be ok and 1.5hp is risky.

What is the point to show electricity bill? The bill didn't show how many hours you use your AC also didn't show how many percent of the bill belongs to AC consumption. I used to have bill with RM50 because I went overseas for half month. I also have bill of RM 300 because my sister's family stay with us for one month.

Don't use AC and don't use fan, don't use light use candle is even better. Just different preference. Also consider to sleep naked. Or stay at gothong jaya.
This is true that using fan with AC will increase covention heat loss to bring down skin temperature. But not everyone prefer to sleep with fan plus AC. One reason is higher noise lever. Another reason is dry skin due to high convection heat loss.

3 cores=non inverter

3 core=non inverter=EER is 12.45 lower than 4 core=inverter =EER is 12.73
Higher EER means more efficient. Every W of electricity you use is able to remove 12.73Btu/h of heat is better than every W input only able to remove 12.45Btu/h of heat.
So inverter at full load still more efficient.

Not few times just around 62% at 35degC. At ambient temp 35deg C, R22 is 181.9psi, R410A is 295psi. Our R22 gas piping for 1.5hp was rated around 400psi WORKING PRESSURE.

Can't say safe but usable in theory. 1 hp definitely safer. 1.5hp you have less safety factors.

The room too cold or lack of gas.

If on at night and non-inverter then 1.5hp is good enough. Which around 35-40btuh/sqft. Just make sure the air can reach your seating place. Daikin is good enough for non-inverter. Just get the R410A model which is slightly more efficient. Daikin spare parts also easier to obtain.
I don't think non-inverter can reach 5 star....
My view is if you didn't use the A/C frequent enough then you hardly save enough on electricity to cover the difference between inverter and non inverter which is around RM800. The truth is inverter are using more circuit board and easier to burn then non-inverter. The outdoor circuit board for 2hp inverter is not cheap....
My vote go to 1.5hp non-inverter for your case.

This post has been edited by keyser soze: Nov 19 2015, 01:37 PM

If money is not an issue then why not. But 2hp might be a bit over if you use it at night. Just elec bill a bit higher.
BTW the Mitsubishi you posted is premium series, if the price is slightly more expensive than Daikin, you should consider that.

The person who service the A/C might be electrocuted if there are current leakage, because your ELCB won't trip if there are current leakage. Some claim that the copper pipe is already a very good earthing conductor, but I don't think it is 100% accurate.

Fridge running 24hr. You will be amaze with the saving you get.

I don't have formula to calculate. My experience is after I install 2 nos. 1hp inverter AC to replace the non-inverter AC, my monthly saving is around RM60-70. Then after replace my 30+ years old fridge to much bigger Hitachi inverter fridge, further saving is around RM90 to RM100. Before I replace the fridge I did extensive research on what kind, which brand and which model of fridge. I even go to Singapore NEA website to check the power consumption of different model of fridges. Just remember fridge is something that running 24hr....

This is depends on how energy thirsty is your existing fridge.

Evaporator coil only wet. Not condenser.

Inverter was in the market for more than 15 years (when I just join this line 15 years ago they already exist). They used to be expensive to own and repair due to new technology that time and demand is low.
Now a day inverter is more common so the parts price should be lower, and should be more reliable due to established technology. My point of view is non inverter IC board is still much cheaper than inverter ic board, but not as much like last time.
If you use your A/C for long hours like 6 to 8hr a day then you should go for inverter.
If you just need a normal inverter A/C without some funny functuion, my recommendation is Daikin, since they are local made, so the parts should be cheaper than those made in China or Thailand. You can even walk in to their parts department at Damansara Utama to buy yourself.
My 2 units made in Thailand R22 Daikin inverter served me 8hrs a day for 2 years without any problems. Now feel like upgrading to Urusara 7, hopefully can get a free unit from Daikin next year.

I think I can get it much cheaper, but my plan is to get it free.

Buying Urusara is like buying ferrari. When you buy ferrari you don't worry about the maintenance. Just enjoy.

What so funny?

Last month only, in 2 days they delivered RM1.6mil worth of VRV4 outdoor units to my project. How hard to meet their target?
After last financial year, they send us 5 units of Non inverter for free. I think with 3nos. 1hp and 2nos 1.5hp.
Are you Daikin dealer?