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HJ Residence

its our home, truly............

Which Aircon Should I Install?

I received this email from a reader recently.

'Dear HJ Residence,

Your articles on aircon issues is very interesting and something that I encountered before.

Let me share my experience. About 6 years ago we bought a resale 4 room flat. ( my input: for the benefit of readers who is not familiar with Singapore's context, a 4 room flat is a subsidised housing development by the government for Singaporeans. How much is the subsidy, I do not know. A 4 room flat is usually a 3 bedroom apartment. The other room will be the living/dining room. How this term is coined, I do not know that too!) As the flat is quite old, we decided to renovate the entire flat. We told our contractor that we wanted to air-condition the whole apartment. He said no problem. He brought some catalogs from a few brands. We were recommended a system 4 and to pick a Japanese brand. Although a Japanese branded aircon is more expensive, we decided to proceed with it. After the renovation, everything was perfect. Unfortunately, we didn't think of running all the 4 aircon concurrently until my housewarming party some 3 months later. We turn on all the aircon but with about 20 people in the flat, it was like a sauna. Quite embarrassing too as we had to turn on the fans as well. The following Monday, I called the contractor to complain. He asked if I did any maintenance. I said no as we only turn on the aircon in the bedroom. He said to engage an aircon specialist to service and check and recommended one. They came a few days later, check and clean all the aircons. That weekend we turn on all the 4 aircons as we have a few friends for dinner. And it is still not cold that we again turn on the fan. I call my contractor again on Monday and complain. He said he will send another aircon specialist. I said I already paid one last week and not going to pay another one. He said he will tell the aircon specialist not to do any servicing. A few days later another group of servicemen came. They came, remove the covers and some parts then told me some component damaged! I said the aircon is new and it should under warranty. He said he can claim the warranty for the parts but have to charge me the labour cost! I was furious and called my contractor. He said if part damage, only the material is covered under warranty but not labour charge. So I told the aircon servicemen to pack up. He said, If I'm not replacing the parts then he needs to charge me for mobilization and checking. I'm left with no choice but to change the part since they're still charging me anyway. After they complete, I immediately turn on all the aircon. After about 30 minutes, it is still not cooling down the flat. The servicemen said I'll have to wait a bit more because the part is very new and left. All the aircons are turned on from 3pm and at 7pm it is still not as cold as I expected. When I call the servicemen the next day, he told me that may be another component in the system may be damaged. I was really furious. I gave up and look for another aircon specialist on the website. He came the next day and checked. He said that there's nothing wrong with the aircon. Just that the capacity is not enough. To cool down the whole flat I need to add another system 2. Told told him that's not possible as the flat has just been renovated and I don't wish to have extra pipings and messy works. Told him I will consider. He said for my system 4, the best it is only use as a system 3 for the bedrooms. I've totally given up after that. Till now, I'm just living with it. That's the problem I face previously.

Now my new apartment is going to be ready in a few months time. Based on your articles I read, you seem quite familiar with aircon systems. Can you help to recommend which aircon or what brand should I use for the new place?

Thank you very much if you can help.



Dear Teoh,

I am sorry to hear of your predicament and thank you for finding my articles is of interest to you. Unfortunately the aircon specialist that you contacted is correct. More than likely, the cooling capacity of the system is insufficient to cool down your entire flat. A system 4 configuration does not mean that it will cool down 4 areas.

There are certain calculations that needs to be applied to sum up the minimum cooling capacity of an enclosed space. This is by no means exhaustive. As a guide, a space of about 4m x 3m with a ceiling height of about 2.8m would require about 9 200 Btu to cool down the area. (Btu : British thermal unit is used for the measure of power in steam, heating and air conditioning industries.) This will be a typical bricked room with a door and some windows. Not a glass house! I shall not get into further details as it will then be exhaustive.

Which brand you decide is a personal decision. (marketing and branding perhaps) What you should look out for is the cooling capacity of the outdoor Condensing Unit (CU).

For example, the cooling capacity of the CU is 22 000 Btu. You connect 3 indoor Fan Coil Units (FCU) each with a cooling capacity of 9 000 Btu. Now, when you turn on the 3 FCUs, the total load required is 27 000 Btu. However, the maximum cooling capacity of the CU is only 22 000 Btu. Thus, each FCU will not run at full capacity of 9 000 Btu but at about 7 300 Btu. If the CU is connected to another 9 000 Btu FCU, at full load, each FCU is actually running at 5 500 Btu. In short, the capacity of the CU is crucial ! You need to check the technical specifications of the aircon system prior to committing.

For your new apartment, what I would recommend is to first establish the areas you want air-conditioned and then work out the minimum cooling capacity. With that information, you then source for the air-conditioning equipment.

If you'd buy me lunch at your local deli, I can assist you to size up your cooling capacity requirement! Throw in a beer, I'll go shopping with you for your air-con system!

Hope the above helps.

Your Friend,