How to Install your own Air Conditioner

How to Install your own Air Conditioner

March 3, 2019 tips 0


So, you decided to install your own air conditioning system. This is a big task, and you need to plan it carefully to anticipate any potential problems. The location of the unit is a fundamental choice that will affect the whole job, so you should consider the various alternatives carefully to give yourself the easiest task. Ensure that you read about the ductwork design and installation before finally settling on the location. We still highly recommend you to engage the aircon vendor to install it for you or the very least get in touch with any aircon servicing company to assist you. There’s many home services out there for you to choose from.

If you have decided to install it on your own, then let’s continue. A second decision is where to locate the thermostat. You need to run wires between this and the unit, and the thermostat should be in a representative place so that you are satisfied with the control. Be careful that the thermostat location doesn’t get direct sunlight at any time of the day, as this will dramatically affect the function.

If you can, you should get the installation manual for the unit before it is delivered, and study it carefully. Apart from ensuring that the unit works properly, you will find any warranties void if you do not comply with these instructions for installation and use.

Whatever unit you buy, it will be fairly heavy, so you need to make sure that it can be delivered close to its final location. If you are putting a packaged unit on the roof, you should arrange to rent acrane and operator to lift it into place – ideally, this can be directly from the delivery truck, but you need to be very sure that you prepare the mounting area fully before it arrives so that the installation goes smoothly. You can get prefabricated mounting curbs, and you should make sure that it is for your precise pitch of roof, as the unit needs to be level to work properly.

If you are installing it on the ground, you will need to prepare the site carefully, and put down a concrete slab of appropriate dimensions. The location of a packaged or split system unit on the ground needs to be reviewed carefully, as there are certain distances required for equipment access for repair and maintenance, and clearances required from walls or vegetation to allow proper airflow and operation.

If you are not replacing an existing unit, you will need to install new circuit breakers of the correct rating in your electrical panel. Even if you are replacing a unit, you should check the ratings for the new equipment.


Packaged Unit

This is the simplest unit to connect up. Just run the electricity and connect the thermostat as detailed in the instructions, and it should be ready to function. There will be a drain from the condensate tray which can discharge on to the roof in some jurisdictions, but would be better routed to the ground, as running water on the roof can deteriorate the surface. Try to discharge in an inconspicuous place, such as a planter, and avoid water on walkways.


Split System

The indoor air handling unit is commonly above the ceiling, or may be a vertical unit in a closet. If the unit is over the ceiling, you will need to have two methods of disposing of the condensate, both for practical reasons, and because most jurisdictions now require it. The first is the regular condensate connection from the unit. The second is in case the first blocks and overflows, which would damage the ceiling. A larger catch pan under the unit is connected to pipe away any such spillage. This secondary condensate pipe should discharge somewhere where it will be noticeable, as you will want to know that the primary arrangement is not working.


Gas Package Unit

With the addition of gas piping, this unit has additional complication. As gas can be dangerous, you should only do this piping if you are confident of your ability, otherwise get a registered contractor. Be sure to test the gas piping for soundness before use – you can use an old paintbrush and washing up liquid solution to brush over each joint, and if bubbles form, you have not been successful in your work!



There are manuals devoted to duct installation and variations in layout, however provided you take care in installing the duct to not have any leaks and to have a gentle air path, you should be alright with the following guidance. It is common for ducts to leak and not distribute the air efficiently, but this can be overcome with due care. Duct systems should be installed within the air conditioned space as far as possible. That way, any leakage will not be completely lost, but will still provide general cooling. As far as possible, you should use hard ducting.


Sheet Metal Duct

These must be carefully sealed with tape, or, preferably, with mastic on each joint. Sheet metal screws should be used on all joints, and insulation is required to stop condensation.

Fiberglass Duct Board

This is insulated as part of its construction. It also provides excellent sound attenuation. Connections should be mechanically fastened using V-groove or ship-lap joints and stapled and sealed with approved tape and mastic.

Flexible Ducting

This is often used for run outs to the grilles, and is made of a vapour barrier jacket over spiral wire, with blanket insulation inside. There may be fewer connections than with some ducting, reducing the opportunity for leakage, but it is easily torn during or after installation, and has a high resistance to airflow. It should be stretched out during installation, using the minimum length to connect two points, which reduces the possibility of bunching and sagging. Connections and joints must be mechanically fastened with draw straps, and should be sealed with mastic. Any bends shouldn’t be more than 90º, and have a radius at least as large as the duct diameter.

Duct Boots and Elbows

Duct boots are preformed fittings which connect the ducting to registers and grilles. These must be sealed with mastic or approved tapes. They should be installed through the wall or ceiling and sealed around before putting on the grilles.


Window Air Conditioner

With the correct unit, the installation of a window unit is simple. Just follow the instructions, which will include opening the window, putting the unit in place through the hole, and sealing around the unit to prevent draughts – it’s literally that simple! Oh, apart from plugging it in. These units are great for the appropriate situation, but are limited in performance and can be noisy. For treating an individual room, however, they are an easy answer, particularly for rental accommodation, as they can also be taken with you when you leave.

Information courtesy from Mike Newberry from the Aircon Repair


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