For those of you buying Air-conditioners for the first time. Especially those that are installing in their newly purchased HDB unit. You might be bombarded with a lot of questions. What is Aircon system 4? What is BTU. For a simpler guide, you can check out FULL WALKTHROUGH on Aircon installation in HDB. For those of you who are installing Air-conditioner in all of your bedrooms and also your living room. You might actually wonder, is it better if I just install a system 4 ac unit. Or would it be better if I Install 2 condensing unit, For example install a set of system 3 and another set of system 1. So should I get Aircon system 4 or 3+ 1? In this Article, we will explore this question.
Definition of Aircon system 4 or 3 + 1
To understand deeper on the question. We first have to define what is Aircon system 4? System 4 refers to the condensing unit having 4 outlets. Which means It has the ability to connect to 4 blower unit (or indoor unit) at the same time. Which means, you can technically use a system 4 to connect to 3 indoor units, leaving one of the outlets untouched. For System 4 Aircon, in this instance we are referring to installation in 3 bedrooms and living room for a HDB unit.
Btu for Aircon
Aircon system 4
For a system 4 unit, we need to know the model number and the maximum capacity of it. For example, Mitsubishi system 4 FN series, there are 2 model : MXY-4G33VA2 and MXY-4G38VA2. The more commonly used model will be MXY-4G33VA2. For this particular model, it has a maximum btu of 36000. If you need more information on BTU, you can check out our article on Aircon installation. Next, you will also need to know how much btu do you need for you living room. For a 5 room flat, you will typically need 21000 – 24000 worth of btu. As for 4 room flat, it’s around 18000. For a 3 room flat about 12000 will do. Nevertheless there could be exceptions to these rules. And it will best if you ask an experienced AC technician to head down to check. Assuming that your house is a 4 room flat, your living room will need about 18000 btu. For HDB units, each of the room will need about 9000 btu ( you will actually only need 6500 btu for normal size room). If you sum that up you will need about 45000 btu for all of the rooms combined. Hence, if you were to use a Mitsubishi system 4 Mxy-4G33VA2, you will not be able ensure that all rooms are cold if you were to turn on all the blower units at the same time. Because the maximum bto for MXY-4G33VA2 is ony 36000 btu.
Aircon system 3 + 1
Hence to make sure that all of your rooms including living room is cold. You will need a total btu of 45000. This is where Aircon system 3 + 1 comes into play. Let’s use Mitsubishi as an example again. Mitsubishi system 3 Mxy-3g28va2 has a a btu of about 30000 btu. Mitsubishi single split unit Muy-gn18va has a btu of 18000. If you add up these 2 together, it has a combined btu of 48000, it is definitely more than sufficient to ensure all of the fancoil units are cold when it’s turned on together. Nevertheless, if that is the case why don’t everyone install 2 condensing units instead of a system 4 condensing unit?
Comparison between Aircon System 4 or 3+ 1?
A system 4 AC is definitely cheaper than that of 2 condensing units combined. Because a compressor is the most expensive component in an aircon parts. Having 2 condensing unit will be a lot more expensive than having just one big one. Let’s use Mitsubishi as an example again. A Mitsubishi system 4 Mxy-4g33va2/ FN10ve x 3 + FN18VE (9000 btu x 3 + 18000 btu) cost about $3800 for HDB. Where as Mitsubishi system 3 Mxy-3g28va2/ fn10ve x 3 and a Mitsubishi system 1 Muy-gn18va/ msy-gn18va cost about $4300 combined. That’s a cost saving of $500. Thefore based on cost alone, most consumers would opt to get a System 4 instead of a system 3+1
Having 2 sets of condensing unit will definitely consume more electricity than just one system 4 aircon unit . That is because 2 compressor running at the same time will consume more power than just one. So if you were to use a system 4 ac, you will see a nicer electricity bill at the end of the day.
For HDB units without an Air-con ledge, not every house can install 2 sets of bracket. You will need a metal bracket to place your Aircon condensing unit on. You will also have to call up HDB and check before you can install. It has to go hdb electrical upgrading to install 2 condenser. Hence based on this additional paperwork itself, it turns off many hdb home owners on installing an additional set of condensing unit in their house. For hdb units with Aircon ledge, the feasibility of installing 2 sets of condensing unit will depend on the Window height and the size of the ledge. Not every ledge is big enough to contain 2 sets of compressor. For example, for some of the smaller ledge, the condensing unit actually has to be placed diagonally. This is to ensure that the hot air blowing out from the condenser unit will not be obstructed. If it is obstructed it will cause overheating for the compressor. For HDB 5 room flat, only 24000 btu is suitable. However the size of the condensing unit for a 24000 single split is very tall. There might be some house that have window height constraints for this particular condenser unit. Hence, before you make any decision on whether to get 2 compressors. It might be best to call us up and check first.
How about system 2 + system 2 instead?
2 sets of system 2 is also a viable choice. However in terms of electricity consumption, it is usually better to get a system 3 + 1. Most of the time, the air-conditioner in the living hall will not be turned on when everyone in the household goes to sleep. Which means only one compressor will be running if you were to use a system 3. If you were to use two sets of system 2m there will be 2 condensing unit running at the same time if you turn on the ac for all 3 bedrooms. This will result in unnecessary additional electrical cost.
After reading this article, I hope you have a better understand of whether you should get Aircon system 4 or 3+ 1. If you still have any more question, do feel free to call us for a free tele-consulting session. Our technicians are able to go down for a free site survey should you be interested in buying Air-conditioners.