Air conditioning - Any recommendations please?? - Part 2

[SE4N23]

Why is it people only care about the btu of their indoor units but not their outdoor compressor unit ?
MXY4H38VG is normal rated at 27.3k btu
MXY3H28VG is normal rated at 20.4k btu

Option 2 will definitely be better than option 1 as you have a dedicated outdoor compressor to support your 24k btu indoor unit. The disclaimer however is that you will only be using 2 of your 3 9k btu indoor units as MXY3H28VG at 20.4k btu cannot fully support all the 3 9k btu (3 x 9k = 27k btu) indoor units. You will be better off getting the MXY4H38VG to support your 3 x 9k btu indoor units.

Some people will disagree with me to say that at night, temperature is lower and you don't utilise the full 9k btu of the indoor unit, so you can get a lower btu outdoor compressor unit. But if the temperature gets hot (like now), that will be the time that you will regret your decision.

Temperature is really rising and we do need higher capacity theoretically. However, room sizes are getting smaller as well. Agree that ideally outdoor capacity should match indoor capacity, but diversity has always been the purpose of multi spilt system.

And how do we know bedrooms do need 9k? why not 7k, 8k etc?

Not trying to challenge, just healthy discussion, no offence.

 

[SE4N23]

Thanks, my ID's AC contractor is also using SWG21 and 1/2" class 0 insulation armaflex and is on average 10-15% more expensive than other contractors outside (using SWG22 and 3/8" insulation), i guess that's why my ID's AC contractor is more exp.

Make sure drainage pipe at least 16mm as well

 

[1BadAssLobster]

the worst is many use SWG 22 which mean more problem later. heng i have not buy yet, so now i will insist on SWG 21

change the insulation to armaflex shield CX if possible

Wah sian, I order online from Audio House already, wonder if they allow me to upgrade further to SWG 21.

 

[KYLee]

Make sure drainage pipe at least 16mm as well

Thanks, according to the quotation, drainage is 16mm.

 

[The_King]

Wah sian, I order online from Audio House already, wonder if they allow me to upgrade further to SWG 21.

just call them tml. hope you can upgrade to the correct thickess

 

[The_King]

Temperature is really rising and we do need higher capacity theoretically. However, room sizes are getting smaller as well. Agree that ideally outdoor capacity should match indoor capacity, but diversity has always been the purpose of multi spilt system.

And how do we know bedrooms do need 9k? why not 7k, 8k etc?

Not trying to challenge, just healthy discussion, no offence.

i always tell ppl this if cold i can wear more clothes, if i hot, i cannot strip naked

 

[Barracudaz]

Why is it people only care about the btu of their indoor units but not their outdoor compressor unit ?
MXY4H38VG is normal rated at 27.3k btu
MXY3H28VG is normal rated at 20.4k btu

Option 2 will definitely be better than option 1 as you have a dedicated outdoor compressor to support your 24k btu indoor unit. The disclaimer however is that you will only be using 2 of your 3 9k btu indoor units as MXY3H28VG at 20.4k btu cannot fully support all the 3 9k btu (3 x 9k = 27k btu) indoor units. You will be better off getting the MXY4H38VG to support your 3 x 9k btu indoor units.

Some people will disagree with me to say that at night, temperature is lower and you don't utilise the full 9k btu of the indoor unit, so you can get a lower btu outdoor compressor unit. But if the temperature gets hot (like now), that will be the time that you will regret your decision.

Sorry for asking those questions as I am not familiar with the technical terms. And those vendors just keep trying to push those underpower compressor unit and convinced me that these units/combinations are sufficient. Then i raise those question here to seek for a more neutral opinion, then i realized how wrong those vendors are

Now I get a sense of idea which combination of aircon to choose. Really thankful for everyone input! You guys just helped me save a ton of headache in the future.

 

[reiser]

How do you decide what’s the btu to get? An ID told me to get 9btu for bedrooms and 12btu for living and dining rooms. But it seems to me most people are getting 24btu for living room, 12btu for master bedroom and 9btu for other bedrooms.

Is there a measurement I should follow?

 

[Carbuncle]

Hi everyone,

I’m thinking of replacing the fan coil and compressors units in a 3 bedroom condo unit before I move in, so I was hoping to get the views of the gurus here.

The current set up:

• Living/dining area (32 square meters) - 2 x 15000 BTU fan coil units
• Bedroom 1 (15 square meters) - 1 x 15000 BTU fan coil unit
• Bedroom 2 (11 square meters) - 1 x 11000 BTU fan coil unit
• Bedroom 3 (8 square meters) - 1 x 9000 BTU fan coil unit

Living/dining area is supported by one compressor, bedrooms 1 and 3 are supported by another compressor, and bedroom 2 has another compressor. Not too sure what the BTU capacities are for the existing compressors though.

For my intended usage, the living/dining area aircon will be on for the whole day as I usually WFH. Aircon for Bedrooms 1 and 2 will be switched on throughout the night and periodically in the day, whereas the aircon in bedroom 3 will probably only be used for 2-3 hours a day at most. My contractor has given me 2 quotes.

Option 1 - Mitsubishi

• MXY-4H38VG / 2x MSXY-FP18VG - for living /dining area
• MXY-4H38VG / 2x MSXY-FP18VG - for bedrooms 1 and 3
• MUY-GP13VF / MSY-GP13VF - for bedroom 2

Option 2 - Daikin

• MKM85VVMG / 2x CTKM50VVMG - for living / dining area
• MKM85VVMG / 2x CTKM50VVMG - for bedrooms 1 and 3
• RKM35PVMG / FTKM35PVM - for bedroom 2

Any views from the gurus here on Options 1 vs Option 2?

Is Daikin preferred to Mitsubishi or vice versa?

I am wondering whether it’s overkill to have the same BTU rating fan coil unit for bedrooms 1 and 3, because bedroom 1 is much bigger than bedroom 3.

And also wondering whether I need to go and check if the existing piping can support the 2 new options - seems like the existing set up uses R410A refrigerant and the new options will use R32 refrigerant? The contractor says the piping is still good and is not leaking but is there anything else I should be looking out for?

Lastly, I am not very familiar with aircon pricing, but are they controlled by the agent? I’m being quoted between $8-9k for Options 1 and 2 (no piping work, just dismantling existing units and installing the new ones). Should I compare the pricing by getting multiple quotes from places like Gain City?

Thanks so much for everyone’s help!

 

[GBC]

How do you decide what’s the btu to get? An ID told me to get 9btu for bedrooms and 12btu for living and dining rooms. But it seems to me most people are getting 24btu for living room, 12btu for master bedroom and 9btu for other bedrooms.

Is there a measurement I should follow?

You can work out an estimated btu requirement from here :-

https://www.calculator.net/btu-calculator.html

 

[GBC]

Hi everyone,

I’m thinking of replacing the fan coil and compressors units in a 3 bedroom condo unit before I move in, so I was hoping to get the views of the gurus here.

The current set up:

• Living/dining area (32 square meters) - 2 x 15000 BTU fan coil units
• Bedroom 1 (15 square meters) - 1 x 15000 BTU fan coil unit
• Bedroom 2 (11 square meters) - 1 x 11000 BTU fan coil unit
• Bedroom 3 (8 square meters) - 1 x 9000 BTU fan coil unit

Living/dining area is supported by one compressor, bedrooms 1 and 3 are supported by another compressor, and bedroom 2 has another compressor. Not too sure what the BTU capacities are for the existing compressors though.

For my intended usage, the living/dining area aircon will be on for the whole day as I usually WFH. Aircon for Bedrooms 1 and 2 will be switched on throughout the night and periodically in the day, whereas the aircon in bedroom 3 will probably only be used for 2-3 hours a day at most. My contractor has given me 2 quotes.

Option 1 - Mitsubishi

• MXY-4H38VG / 2x MSXY-FP18VG - for living /dining area
• MXY-4H38VG / 2x MSXY-FP18VG - for bedrooms 1 and 3
• MUY-GP13VF / MSY-GP13VF - for bedroom 2

Option 2 - Daikin

• MKM85VVMG / 2x CTKM50VVMG - for living / dining area
• MKM85VVMG / 2x CTKM50VVMG - for bedrooms 1 and 3
• RKM35PVMG / FTKM35PVM - for bedroom 2

Any views from the gurus here on Options 1 vs Option 2?

Is Daikin preferred to Mitsubishi or vice versa?

I am wondering whether it’s overkill to have the same BTU rating fan coil unit for bedrooms 1 and 3, because bedroom 1 is much bigger than bedroom 3.

And also wondering whether I need to go and check if the existing piping can support the 2 new options - seems like the existing set up uses R410A refrigerant and the new options will use R32 refrigerant? The contractor says the piping is still good and is not leaking but is there anything else I should be looking out for?

Lastly, I am not very familiar with aircon pricing, but are they controlled by the agent? I’m being quoted between $8-9k for Options 1 and 2 (no piping work, just dismantling existing units and installing the new ones). Should I compare the pricing by getting multiple quotes from places like Gain City?

Thanks so much for everyone’s help!

First of all, you need to right size the BTU requirement for your respective rooms. For the size that you have indicated, the estimated requirement is as follows :-

• Living/dining area (32 square meters) - 14k btu required
• Bedroom 1 (15 square meters) - 9.5k btu
• Bedroom 2 (11 square meters) - 9k btu
• Bedroom 3 (8 square meters) - 9 k btu

So you can consider maybe getting :-
1 x single split unit for your Living/dining area of around 16k to 20k btu. (MUY-GP18VF/MUY-GP20VF or equivalent)
1 x system 4 multi split unit for 3 bedrooms of 9k btu each of around 27k btu (MXY-4H38VG or equivalent)

Like The_King mentioned earlier R32 aircon is recommended to have SWG21 copper piping. If you intend to change a new aircon system, just change all the old piping as well.

 

[The_King]

First of all, you need to right size the BTU requirement for your respective rooms. For the size that you have indicated, the estimated requirement is as follows :-

• Living/dining area (32 square meters) - 14k btu required
• Bedroom 1 (15 square meters) - 9.5k btu
• Bedroom 2 (11 square meters) - 9k btu
• Bedroom 3 (8 square meters) - 9 k btu

So you can consider maybe getting :-
1 x single split unit for your Living/dining area of around 16k to 20k btu. (MUY-GP18VF/MUY-GP20VF or equivalent)
1 x system 4 multi split unit for 3 bedrooms of 9k btu each of around 27k btu (MXY-4H38VG or equivalent)

Like The_King mentioned earlier R32 aircon is recommended to have SWG21 copper piping. If you intend to change a new aircon system, just change all the old piping as well.

thank for you earlier post that talka bout inner diameter. else i still blur blur.

 

[Carbuncle]

First of all, you need to right size the BTU requirement for your respective rooms. For the size that you have indicated, the estimated requirement is as follows :-

• Living/dining area (32 square meters) - 14k btu required
• Bedroom 1 (15 square meters) - 9.5k btu
• Bedroom 2 (11 square meters) - 9k btu
• Bedroom 3 (8 square meters) - 9 k btu

So you can consider maybe getting :-
1 x single split unit for your Living/dining area of around 16k to 20k btu. (MUY-GP18VF/MUY-GP20VF or equivalent)
1 x system 4 multi split unit for 3 bedrooms of 9k btu each of around 27k btu (MXY-4H38VG or equivalent)

Like The_King mentioned earlier R32 aircon is recommended to have SWG21 copper piping. If you intend to change a new aircon system, just change all the old piping as well.

Thank you for your guidance!

May I clarify:

1) how do we get the BTU requirement for each room size? Is there a formula or table to refer to? For eg Gain City says take square footage multiply by 65 but also then have to add on more BTU in certain scenarios after multiplying?

2) on your suggestion of system 4 unit for 3 bedrooms (each 9k BTU), I see that overall the capacities of the 3 fan coil units match the capacity of the compressor unit (9k x3 = 27k BTU), will that strain the compressor unit in the long run?

3) following on from item 2 above, and for my understanding, if I look at the 2 options from my contractor for the living/dining area (or bedrooms 1 and 3 for that matter), it seems like the compressor unit capacity (Mitsubishi 27k BTU, Daikin 25k BTU) is not enough to power the 2 fan coil units that are connected to it (2 x 17k = 34k BTU). Does that mean that the compressor will be strained / cooling ability of the fan coil units will be affected if both are switched on?

 

[GBC]

Thank you for your guidance!

May I clarify:

1) how do we get the BTU requirement for each room size? Is there a formula or table to refer to? For eg Gain City says take square footage multiply by 65 but also then have to add on more BTU in certain scenarios after multiplying?

2) on your suggestion of system 4 unit for 3 bedrooms (each 9k BTU), I see that overall the capacities of the 3 fan coil units match the capacity of the compressor unit (9k x3 = 27k BTU), will that strain the compressor unit in the long run?

3) following on from item 2 above, and for my understanding, if I look at the 2 options from my contractor for the living/dining area (or bedrooms 1 and 3 for that matter), it seems like the compressor unit capacity (Mitsubishi 27k BTU, Daikin 25k BTU) is not enough to power the 2 fan coil units that are connected to it (2 x 17k = 34k BTU). Does that mean that the compressor will be strained / cooling ability of the fan coil units will be affected if both are switched on?

1) You can get the BTU per room estimate here
https://www.calculator.net/btu-calculator.html
2) An optimal aircon system is one where the normal rated BTU on your outdoor compressor unit can support the total normal rated BTU of all your indoor units combined. What it means is that when you switch on all your indoor units at the same time, all of them can run at its rated BTU capacity without straining the outdoor compressor.

3) If your outdoor compressor unit is rated at let's say 25k btu and you have 2 x 17k = 34k btu indoor units running at the same time. What will happen is that your underpowered compressor unit can only support around 75% of the rated capacity of your 17k btu indoor unit, so your 17k btu indoor unit will only run at maybe around 12.5k btu instead of its normal rated 17k btu.

However, if you only run 1 x 17k btu indoor unit, it will run at 100% of its rated 17k btu as your 25k btu compressor unit is more than sufficient to support it.

 

[anddrool]

Another alternative is to get a system 5.
System 5 compressor 44.4K BTU max MXY5H48VG

You can place 2 9k BTU in the living. 2 fan coil is able to spread and cool under space more efficiently.
9k BTU in each room.
The compressor is able to support all aircons to be on at the same time. In most of the time, probably 2-3 aircons is only on at the same time. And the compressor is running at optimal load (around 60% load). Aircons will be cold since compressor is not taxed at full load.

Another benefit is if by just using 1 system, you will be able to save electricity used when system is in stand by. 2 systems will use more electricity since 2 system are in stand by.
It might not seem a lot per month. But if it is calculated through a span of 10 years. Then the saving will be a lot.

Some will say that 2 systems is better and will last longer since it is less used.

But I will go for 1 system 5 since I will save on installation cost, additional wiring cost, electricity cost, compressor will not be running at full load most of the time. All the cost saved, can be used to replace or repair the aircon in the future.
This is my 2 cents.

 

[petetherock]

1) You can get the BTU per room estimate here
https://www.calculator.net/btu-calculator.html
2) An optimal aircon system is one where the normal rated BTU on your outdoor compressor unit can support the total normal rated BTU of all your indoor units combined. What it means is that when you switch on all your indoor units at the same time, all of them can run at its rated BTU capacity without straining the outdoor compressor.

3) If your outdoor compressor unit is rated at let's say 25k btu and you have 2 x 17k = 34k btu indoor units running at the same time. What will happen is that your underpowered compressor unit can only support around 75% of the rated capacity of your 17k btu indoor unit, so your 17k btu indoor unit will only run at maybe around 12.5k btu instead of its normal rated 17k btu.

However, if you only run 1 x 17k btu indoor unit, it will run at 100% of its rated 17k btu as your 25k btu compressor unit is more than sufficient to support it.

Thanks
I think most posters need the info on the right compressor size
Those BTU calculations don’t show that part ..

 

[1BadAssLobster]

just call them tml. hope you can upgrade to the correct thickess

They only provide 22G, dont have 21G. Saw from your thread at edmw, others showed that 22G rated for 1000psi and R32 operate at 300+psi max, think is safe enough given the current circumstance.

 

[devilcup]

First of all, you need to right size the BTU requirement for your respective rooms. For the size that you have indicated, the estimated requirement is as follows :-

• Living/dining area (32 square meters) - 14k btu required
• Bedroom 1 (15 square meters) - 9.5k btu
• Bedroom 2 (11 square meters) - 9k btu
• Bedroom 3 (8 square meters) - 9 k btu

So you can consider maybe getting :-
1 x single split unit for your Living/dining area of around 16k to 20k btu. (MUY-GP18VF/MUY-GP20VF or equivalent)
1 x system 4 multi split unit for 3 bedrooms of 9k btu each of around 27k btu (MXY-4H38VG or equivalent)

Like The_King mentioned earlier R32 aircon is recommended to have SWG21 copper piping. If you intend to change a new aircon system, just change all the old piping as well.

this swg21 or g21 is something new... daikin proshop is recommending g22 piping. Of cos thicker piping is better and less likely to have hole and leak if install correctly

 

[reiser]

I have input the living and dining area sqm (40sqm) into the link provided to calculate the btu required. However, it says the btu required is only approx 10860, which means I probably only need a 9k or 12k btu. However, it doesn’t tally with what most people who own an EM do. Most people install 2 fancoils. One in the living area and another in the dining area.

And since the unit is an EM, I was told that I need to consider the fact that the dining area has a staircase which reaches to the 2nd level, which means my ceiling is not 2.6m.

In that case, how should I input the sqm? Should I divide the two areas and input the area separately ie. dining area will have a higher ceiling (approx 5.2m)?

 

[GBC]

I have input the living and dining area sqm (40sqm) into the link provided to calculate the btu required. However, it says the btu required is only approx 10860, which means I probably only need a 9k or 12k btu. However, it doesn’t tally with what most people who own an EM do. Most people install 2 fancoils. One in the living area and another in the dining area.

And since the unit is an EM, I was told that I need to consider the fact that the dining area has a staircase which reaches to the 2nd level, which means my ceiling is not 2.6m.

In that case, how should I input the sqm? Should I divide the two areas and input the area separately ie. dining area will have a higher ceiling (approx 5.2m)?

If you use the BTU calculator and input a worst case scenario as follows :-
Size : 40 sqm
Room Ceiling height : 5.2m
No of people inside regularly : 4
Type : living Room
Insulation Condition : Poor
Sun Exposure : Very Hot
Climate : Hot

You will get a reading of something like 25,398 btu.
If you change the room ceiling height to 2.6m, you will get 17.071 btu.
If you take the average height of 5.2m and 2.6m (3.9m), you will get 21,975 btu.
So if I were to get a single split unit for living & dinning area, I will get a 20 to 22.5k btu unit (eg 6 to 6.6 kw for starmex).

However if you intend to get a multi split unit, then you divide up the living and dinning area accordingly and do separate computations to get the correct indoor unit for each area.