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Old 19-01-2017, 03:20 PM   #9268
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Join Date: Jan 2002
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As usual thank you very much for your exceptionally detailed explanation. Do i need a MXY-4A38VA or MXY-4A28VA?

In future if i need to on more units example i will have the capacity to do so instead of having the MXY-4A28VA but unable to upgrade it etc? What is the differences in having a MXY-4A38VA or MXY-4A28VA?



From the configuration provided, you have 4 rooms needing cooling. 3 Bedrooms and a living room/dinning room.

In my opinion, there are 4 factors that need to be considered.

1. The capacity sizing'
2. The shape and placement of the FCU/s in each room,
3. Sound level
4. The room temperature setting that you would use,
5. The normal rating when various combination of FCUs are turned on.

1. The GE10VA FCU provides up to 2.5kW or 8.53k Btu, which is sufficient for most if not all HDB rooms size. The 2.5kW FCU can even take room size of 5X5X2.8m (ie area of 25m and ceiling height of 2.5m) with temperature of 13 degrees C different from outside temperature.

2. The placement of the FCU is very important to the way the room is cool.

2.1 Placing the FCU at a corner will restrict the air flow to some parts / corners of the room. The most difficult areas to cool in the room are the corners nearest to the FCU (ie to the left or right of the FCU). When the FCU is placed equally from these 2 corners, it reduces that difficulty for the cool air to reach these places. Placing the FCU at one corner may hamper the air flow to the other corner, living it as the warmest area within the room. Temperature within various parts of the room vary too much such that cooling the warm corner may cause the other areas to be too cold.

2.2 It will also affect the suction of the returned air flow into the FCU and therefore the temperature control of the system. The location of the FCU in a room affects the return air path and the areas where the return air is coming from. A good location will provide a uniform return air from all parts of the room that provides a uniform temperature (with the least temperature difference) of the room. When cold air from one section of the room is returned to the FCU, while other parts of the room is still warm, the system temperature control received that the signal that the room is cool and therefore reduces it cooling capacity, causing hot and cold areas within the room. Some air conditioner uses the remote control to sense the room temperature and transmit the result to the FCU for system management. However, with this, there will still be hot and cold areas in the room if the FCU is incorrectly placed.

2.3 Sometime, the room may have a "L" shape, specially in the living /dinning room. Such shape will affect where the cool air can reach and with only one FCU, it is likely that some areas of the such room will not be cold to the desired temperature unless the whole room is cooled down which may take some time or in some situation not at all when the system capacity is reduced as explained in above point 2.2. In addition, the operating cost in such layout would likely be more than having two well placed FCUs. Two well placed FCUs with lower capacity than one higher capacity FCU can provide better temperature control and faster cooling to the desired cooling areas. This is because such layout can take advantage of direct cooling and as well as better temperature uniformity.

So instead of having one GE18VA which is a capacity of 5kW and placing it at one end of the room with limited air flow to the furthest corner of the "L" shape room, you may wish to have two GE10VA place at each ends of the "L" shape room.

You may wish to know that the GE18VA is of the same size as the GE10VA though the air flow at high setting are 15.1 and 11.4 CMM respectivity. Is 15.1 CMM sufficient to reach the end of the "L"?

Would you like to keep running your GE18VA at high speed to keep the furthest corner cool?

3. Sound level. The sound level for the GE10VA is 19 dB, while that of the GE18VA is 28 dB. At 19 dB, it is really quiet and this is the selling point of the ME and Daikin air conditioners. But these are at low speed. So when you run your GE18VA at high speed, you will be subjected to 49 dB instead of 28 dB as you need to cool those further areas.

....... to be continued.
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