Air Conditioner Buying Guide... and Renting Guide...

Air conditioner buying guide is important in making that critical decision of renting, or buying an air conditioning unit. You need a simple air conditioner buying guide to avoid question like this:

"Will I buy the right air conditioning unit?"

You would rather ask the question,

"What are the critical items I have to do, to select the best air conditioning unit for my building?"

Here comes,

Overview of air conditioner buying guide:

When I say "buying", it is not necessarily purchasing the unit. It can also mean purchasing service from air conditioner rental companies.

Let’s cut to the chase. Here are the suggested steps for your noble quest:

  1. Determine whether you need air conditioning, or not,

  2. Size the required air conditioner,

  3. Select suitable type of air conditioning unit for your building,

  4. Select highest SEER or EER of air conditioning unit, that your ROI permits,

  5. Check with your available budget

  6. Consider alternative, if budget is tight,

  7. Buy, or rent?

Step 1: Do you need air conditioner?

Air conditioner buying guide, step 1Ask yourself whether you really need an air conditioner (the major questions).

  • Does the temperature within your local area gets to the extreme, even for a short while?

  • Does the humidity within your local area gets too high for comfort?

  • Does the plot of summer condition in psychrometric chart suggests the need for air conditioning?

If the answers are yes for most of the questions, then you will need air conditioners.

There are other criteria you might want add, to justify your requirement for air conditioners. Examples,

  • Environment control. From dust and noise,

  • Safety reason, especially in control buildings of chemical plants, and

  • Other, more personalised requirement, for instance, your requirement for quieter cooling option, compared to fans

If your analysis proves that you don’t need air conditioning unit, then it is best not to buy, or rent one. You’re better off with cheaper cooling options like natural ventilation, or fans.

Otherwise, you can proceed to the next step in air conditioner buying guide.

Let’s say, the analysis suggests that you won’t need an air conditioning unit, but you still want it due to your own reasons. It is ultimately your choice. Let’s go ahead with,

Step 2: Sizing air conditioners:

Air conditioner buying guide, step 2Sizing air conditioners will take into account of your heat gain, and heat losses within your building, and balancing it with heat removal or addition by the air conditioner.

The idea of sizing is to prevent oversized units, or undersized units. Over sizing problem is just as bad as under sizing.

Undersized units will not remove or add the necessary heat from the building.

Oversized units will not remove enough moisture within the space, creating "stuffy" condition.

Moving on with our air conditioner buying guide,

Step 3: Select type of air conditioner:

Basic options you have for air conditioner types,

Air conditioner buying guide, step 3

  • Portable air conditioner. Portable units are suitable for spot cooling, small space, and less than 3 occupants per space (with special exception for larger portable units. These are normally rented out to users).

    This type of air conditioner can also be rented from rental companies.

    Suitable for permanent or temporary use.

    Sub categories of portable air conditioning unit are,

    • Residential type portable air conditioners,

    • 12 volt type portable air conditioners, and

    • Marine type portable air conditioners

    This category is the most famous amongst us

  • Window air conditioner. Window units can serve a larger space compared to portable air conditioners.

    Suitable occupant number is from 5 to 6 persons.

    However, installation is required in terms of making a slot on your wall, or window.

    You can also rent this type of air conditioner.

    This type of air conditioner is very popular for small project uses, and mobile offices. Rental companies normally rent out the whole cabin with the unit installed.

    But please make sure that the temporary office or building is approved by the Fire Department, for safety reasons

    Read more on window air conditioners

  • Through the wall air conditioner. Similar to window are conditioners, and normally used in fixed buildings.

  • Ductless, or split air conditioner. Evolution in air conditioning technology.

    Unlike portable, window, or through the wall air conditioners, split units have the condensing unit and evaporating unit separated.

    You would at least want this unit, if low noise is a requirement, as it is quieter compared to previous types.

    Larger variation of this type, can serve a meeting room with approximately 50 occupants.

    Read more on split or ductless air conditioners

  • Central air conditioners. Now, comes the "Lord of The Air Conditioners". That sounds familiar.

    I’ll leave it to your imagination, up to how many personnel, and how big an area you would like to serve.

    It can integrate with a lot of condensers, a lot of evaporators, and a lot of air handling units, coupled with ducted system.


    Of course, you must be very serious, if you're planning to use this type of air conditioning unit

    Read more on central air conditioners

  • Automotive air conditioner. Travelling in an almost enclosed space?

    Hence, air conditioners for automobiles are vital.

    Lowering the windows in a dusty and noisy area, or in a traffic jam, won’t do much for your comfort.

    Let alone, the fuel inefficiency if you lower down your windows at high speeds

    Read more on automotive air conditioners

  • Marine air conditioners are best suited for you, if being on water is part of your pass time activity.

    Humidity of air due to proximity with water, and heat, makes it a worthwhile consideration.

    Read more on marine air conditioners

Cool. We have gone through three steps of air conditioner buying guide.

We know IF we need air conditioners.

We know the SIZE.

And we know the TYPE.

Need we know more on air conditioner buying guide? Yes.

Step 4: Select highest SEER or EER of air conditioning unit, that your ROI permits:

  • SEER is the Seasonal Energy Efficiency Ratio.

    This is the measure of cooling output, per energy input of the air conditioning unit.

    The measurement for this rating is carried out at different intervals of the day, and season.

    In short, this ratio characterises the air conditioner, more accurately compared to, EER

  • EER is the Energy Efficiency Ratio.

    It is similar to SEER, but measurement is carried out once off, at maximum load.

    A unit rated with EER, will have a higher SEER rating.

    Higher numbers of either SEER or EER, is good, as you’ll use less electricity per cooled air you get.

  • ROI is Return on Investment.

    Let’s say that you have decided the size and type of air conditioner you want.

    Naturally, you would want to buy the highest SEER or EER unit for that size.

    However, higher SEER or EER means more money out of your pocket.

    What you have to do is ask yourself,

    1. What is the cost of purchase?

    2. How long would I use it per day? What is the total cost of ownership per year, in terms of maintenance, and electricity?

    3. How long do I want to keep this unit, before upgrading?

    4. How much would I be saving at the end of my ownership, if I choose the better unit?

    Then, compare the total cost of ownership of the air conditioners, for the size you have chosen.

    You know what to choose. The lowest cost of ownership, of course.

Air conditioner buying guide continues,

Step 5: Check with your available budget:

Air conditioner buying guide, step 5Nice. You know what you want, from the air conditioner buying guide.

Now, shall we check the budget?

  • If the budget is enough. Go for it!

  • Otherwise, ask yourself if you can "survive" a little longer without a conditioning unit.

    If the answer is YES, then wait.

    If the answer is NO, then

Step 6: Consider next best alternative:

In the order of,

  1. Go for a lower SEER or EER, then

  2. Consider renting a unit. The best option is, renting a portable unit

I don’t recommend downgrading the air conditioner size, as it will do more harm than good.

Next on air conditioner buying guide,

Step 7: Buy, or rent?

In my honest opinion, rent ONLY window air conditioners or portable air conditioners.

The criterion for renting is TIME.

Temporary use of 1 year or less will worth the renting cost.

Finally, our air conditioner buying guide is complete:

Air conditioners are relatively cheap, compared to the installation cost, operating cost, maintenance cost, and not to say, the headache you get, if you have made the wrong decision in buying a unit.

Therefore, it is only wise to go though an organised way of selection process.

A reliable and well maintained air conditioning unit will last for at least 15 years! So, time spent over here, will pay back in many folds over months.

Worth it? "Oooh yeah!"

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