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BANGKOK 19 May 2019 16:11
MrScratch

Time to have my first A/C unit installed – looking for advice

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For the first time ever I’m looking at having 2 A/C units installed in my house

 

The house electrical supply is prone to regular power cuts , voltage fluctuation and spikes ( 230V down to 195 Volts or lower ) . So from what I have read so far its probably best to steer clear of the Inverter type of A/C unit.

 

The house has a 30Amp electricity meter out in the street and a circuit breaker box in the lounge that has a 63 Amp main cut off / trip unit + a range of individual circuit breakers .

 

There are 2 spare 20 Amp un used circuit breakers in the circuit breaker box.

 

I have tried to use an online BTU calculator , but I can’t seem to get the same results , so can any one please have a look at my room dimensions and give me an idea of what size A/C units I will need for each room ( A and B )

 

Both rooms are bedrooms and the windows are normally left open and the outside walls get very hot to the touch both during the day time and night . The A/C will only normally be used at night time when the windows will be closed . The ceiling has no insulation above it and the loft area gets very hot.

 

Any advice or suggestions would be helpful before I visit an A/C shop to check out the price of each A/C unit and the installation cost .

 

 

Thanks

 AirCon1.jpeg

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30 minutes ago, bankruatsteve said:

Yeah.  I would definitely go with Daikin "inverters" as close to the bottom of the range that you can get.  I'm of the opinion that the voltage "worry" for inverter units is based more on hyperbole than actual statistics (if there are any statistics).

 

And, if your voltage is really on a roller coaster, your equipment will be much happier with an AVR(AVS).

Daikin are currently promoting their products ability to resist power surges and lizards along with decent guarantee on the inverter control. I guess some other brands will be providing similar guarantee. I recently repaired a Mitsubishi inverter board where the L-N MOV was completely blown away along with most of the rectifier stage. 

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My two cents would be provide double pole electrical isolation conveniently accessible near each unit. This allows disconnection of supply when not in use or away for long periods. It also provides easy isolation for cleaning and maintenance.

 

Air conditioner electronics left powered up on standby are open to power surges. Isolation will reduce the risk especially during storms.

 

Example local isolation switch ..

 

switch.jpg.523de75da78b80322331a9d00695f981.jpg

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4 hours ago, MrScratch said:

Both rooms are bedrooms and the windows are normally left open and the outside walls get very hot to the touch both during the day time and night . The A/C will only normally be used at night time when the windows will be closed . The ceiling has no insulation above it and the loft area gets very hot.

 

Any advice or suggestions would be helpful before I visit an A/C shop to check out the price of each A/C unit and the installation cost .

Installation will either be included or about 2,000 per unit. Painting the walls white if they are any other colour will probably reduce the temperature they get to by 10 degrees C, adding any kind of  installation on top of the ceilings will help.

 

if you get inverter units Crossy's numbers will be good and oversizeing is no problem. If you go for non inverters do not oversize as you won't be able to dehumidifie if they cool down the room too quickly.

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7 hours ago, Crossy said:

The quick and dirty size calculation used here is 600-700 BTU per m2.

 

Room A = 18m2 = 10,800 - 12,600 BTU.

Room B = 14m2 =  8,400 - 9,800 BTU.

 

As they are bedrooms you can keep to the lower end or go slightly smaller than that if there's a good deal.

 

With such lumpy power I too would avoid inverter units, it may also pay to use an AVR (Automatic Voltage Regulator).

 

Run one A/C off each of your spare breakers, run 2.5mm2 x 3 core cable to the indoor unit location.

 

If you can get some shading on the outside walls, trees work well and look nice, you'll reduce the heat load significantly.

 

Thanks for the information , I’m going to check out the AVR thing , one area that I’m not sure about is the installation of the external out side A/C unit , from what Ive seen it looks like some units are mounted on wall brackets that lift the unit high up off the ground , the other option Ive seen is where the out side A/C unit sits on a floor mounting bracket or some sort of metal box frame .

 

 

Is it normal to request one of these types of mounting options when talking about the installation cost , and does any one type have an advantage. The other thing Ive noticed looking at other out side A/C units , is some have the pipe work enclosed in white / grey plastic trunking to hide it.

 

 

 

 

Again would that plastic trunking be an option to talk about when discussing the installation cost or would it normally included in the installation cost .

 

Just a thought , would these outside A/C units need some sort of water drain pipe work ?

 

 

 

 

 Floor Mounted.png

 Bracket Mounted .png

 Plastic Trunking .png

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6 hours ago, bankruatsteve said:

Yeah.  I would definitely go with Daikin "inverters" as close to the bottom of the range that you can get.  I'm of the opinion that the voltage "worry" for inverter units is based more on hyperbole than actual statistics (if there are any statistics).

 

And, if your voltage is really on a roller coaster, your equipment will be much happier with an AVR(AVS).

I keep seeing Daikin being recommended and yes the house voltage is like a roller coaster ride ☹️

 

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6 hours ago, Fruit Trader said:

Daikin are currently promoting their products ability to resist power surges and lizards along with decent guarantee on the inverter control. I guess some other brands will be providing similar guarantee. I recently repaired a Mitsubishi inverter board where the L-N MOV was completely blown away along with most of the rectifier stage. 

I would be interested to learn from the A/C shop that I am planning to visit , what the warranty would be on the Daikin inverter control board.

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6 hours ago, Fruit Trader said:

My two cents would be provide double pole electrical isolation conveniently accessible near each unit. This allows disconnection of supply when not in use or away for long periods. It also provides easy isolation for cleaning and maintenance.

 

Air conditioner electronics left powered up on standby are open to power surges. Isolation will reduce the risk especially during storms.

 

Example local isolation switch ..

 

switch.jpg.523de75da78b80322331a9d00695f981.jpg

 

Thanks for the advice , the double pole switch is now on my list . Just thinking about it , the power cuts , voltage fluctuation and spikes only seem to happen during the day time and never at night.

 

 

 

 

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2 hours ago, sometimewoodworker said:

Installation will either be included or about 2,000 per unit. Painting the walls white if they are any other colour will probably reduce the temperature they get to by 10 degrees C, adding any kind of  installation on top of the ceilings will help.

 

if you get inverter units Crossy's numbers will be good and oversizeing is no problem. If you go for non inverters do not oversize as you won't be able to dehumidifie if they cool down the room too quickly.

Thanks , I was wondering about the installation costs , do the installation costs normally include installing the electrical cable from the circuit breaker board to the A/C unit .

 

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Posted (edited)
7 hours ago, MrScratch said:

Thanks , I was wondering about the installation costs , do the installation costs normally include installing the electrical cable from the circuit breaker board to the A/C unit .

 

As the already been noted, no, but worth asking when you purchase.

Edited by sometimewoodworker
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7 hours ago, The Fat Controller said:

It's the INSIDE unit that will have a condensate drain pipe, try to have as few bends as possible and keep it clean !

 

We have 2 Daikin inverter units, they are very quiet and reliable.

 

Outside units are mounted high on the walls under the eaves so they are out of the sun and rain, although a pair of pigeons decided to nest on one.

 

We purchased from Home Pro in their sale, their salesman did a site survey prior to us buying.

 

Fitting was included, the only extra was the plastic trunking, which was charged per metre.

 

Electrical cabling back to the board is unlikely to be included in the price unless agreed with the installer.

Thanks for the info and advice , its appreciated :thumbsup:

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