Ducted Heating & Cooling

Air conditoning cleans and dehumidifies (removes excess moisture) from the air. It also has the task of keeping the air at the temperature you select. Most people think the air conditioning systems job is to add “cold” air to the room. Actually, there is no such thing as “cold,” just an absence of heat, or less heat than our bodies are comfortable with. The job of the air conditioning system is really to “remove” the heat that makes us uncomfortable, and return the air to the room in a “un-heated” condition. Air conditioning, or cooling, is really a process of removing heat from an object (like air).
Your air conditioners compressor circulates a liquid refrigerant called Refrigerant-12 “Freon,”. The air conditioners compressor moves the Refrigerant-12 from an evaporator, through a condenser and expansion valve, right back to the evaporator. The evaporator is right in front of a fan that pulls the hot, humid air out of the room. The refrigerant makes the hot air’s moisture condense into drops of water, removing the heat from the air. Once the water is removed, the “cool” air is sent back into the room.

Although evaporative cooling can provide healthy and clean air around the home, sometimes it’s not the best solution.

1. How do evaporative cooling systems work?

Evaporative airconditioning works on the principle of water saturation. Air is taken from outside, filtered and moisture is added to it. This ‘moisturised’ air is then blown into the house.

2. External evaporative ventilation

Because evaporative systems use fresh air, the space to be cooled must have ventilation to the outdoor area. This means it’s essential for doors and windows to be open while the system is in use.

3. Noise issues from evaporative systems

Evaporative cooling systems tend to be quite noisy, though some brands are noisier than others. If noise is a problem for you, make sure you research the available brands carefully in order to find the quietest possible system.

4. Are these cooling systems appropriate for all homes?

As evaporative cooling systems are ducted, a house must have a roof cavity large enough to accommodate the ducting. The systems can only go overhead; under-floor evaporative cooling is not possible.

5. Evaporative design styles

The cooling unit is placed on the roof and is not particularly attractive, but taking care with its location can make it less obvious. Units are available in a range of colours, so look out for one that blends in with the tones of your roof.

6. Benefits of evaporative cooling

Evaporative cooling systems pump cool, fresh, temperature-controlled air through the house. They are considered to be environmentally friendly and are good for those who suffer from allergies.

The system you choose should depend on the size of the area you are looking to heat. This can be broken down into person, room, space and entire home. If the area you want to heat is small or you will use the heater rarely, you will want a cheap heater – even if it’s a bit more expensive to run, you will still save money in the long run. If you need to heat a large area for long periods, you are better off investing in an efficient heater with low running costs.

Gas ducted heating

Ducted heating distributes fan forced warm air via ducts to each room. Ducts can be installed either under floors or in the roof cavity, with the heating unit positioned outside, under the floor or in the roof.

Outlay cost: high – the heater itself is expensive and you will need to pay for it to be installed. This heating is more suitable if you building a new house rather than retrofitting
Energy efficiency: high
Running cost: low

This consists of a single fan coil under the floor or in the ceiling and an outside condensing unit. In most installations add-on refrigerated cooling will be incorporated with gas ducted heater to make up a dual cycle airconditioning system.

A common question frequently asked is can you put an add-on cooling unit with the heating unit already in my home? The answer in most cases is no! Firstly, the ductwork is not fire rated, not R.1 certified and not large enough to cope with the air volume required for cooling and secondly, in a lot of cases the heating unit itself does not have enough air volume for add-on cooling. It needs either a fan upgrade and in most cases it is better to replace the old system with a new more efficient unit which has variable speed, especially beneficial for zoning.

Add-on cooling it a good alternative due to the fact that you are still using gas ducted heating. However, it is imperative that the set up is done correctly to avoid poor performance, especially on the cooling side. In many cases 3 phase power may be required for mid to large size homes.

Ducted evaporative cooling comprises a central cooling unit, which is connected to a series of outlets. Positioned strategically throughout the house, these outlets, or ducts, are installed in the ceiling while the cooling unit is installed on top of the roof. Cool fresh air flows through these outlets into every room of your home that you want cooled. The cooling unit fan draws in fresh air from outside your house. (The hotter the air is to begin with, the better the cooling effect.) As it passes through moistened pads, the air is cooled and filtered before flowing through the ductwork and into your rooms – just like a cool, refreshing sea breeze.

Advantages of Ducted Heating

• Central Heating Unit: Ducted central heating is a combination of a central heating unit which is connected to a series of outlets.
• Heating for all rooms: Installed throughout your home, these outlets, or ducts, are installed either in the floor or ceiling.
• Installation available for different building styles: If your house is built on a concrete slab, the unit is installed in the roof. If it has space underneath or a very low roof line, the unit is installed outside or under the floor.
• Ductwork is hidden: The ductwork, which connects the outlets to the heating unit, is neatly tucked away out of sight.

Heating is a long term investment so before you even begin looking at heating systems, there are a few things you should consider. For instance, how will future lifestyle changes affect your heating needs?

Think ahead, and purchase a system that fulfills your current needs as well as your future ones. And keep in mind that a good heating system increases the value of your home. The money you spend now is sure to pay off later.

Finally, determine how many rooms you want to heat at any given time. Figure this out, and you’re half way to finding the heating system that’s right for you.

With ducted heating you don’t have to walk out of a warm room into a cold one. You can be watching TV while the kids are in bed and everyone stays warm.

Gas Ducted central heating is the most efficient way to heat your entire house. You can save up to $300* per year in operating costs to heat your entire home using a high efficiency gas ducted heater compared to using gas space heaters.

A household using electrical appliances for heating produces three times** more greenhouse gas emissions than a household using ducted gas appliances.

*Sustainable Energy Authority Victoria, 2004 for a house size up to 150m2
**AGA (Australian Gas Association)

Ducted central heating offers heating flexibility through zoning. Zoning enables you to divide your home into sections so living areas can be heated during the day and sleeping areas at night, or whatever suits you. Zoning is not only practical but economical. It can reduce your gas bill by up to $200 pa. in a typical home. So don’t forget to ask about zoning when you speak to your dealer.

Ducted central heating comprises a central heating unit, which is connected to a series of outlets. Positioned strategically throughout your home, these outlets, or ducts, are installed either in the floor or ceiling. Positioning of the heating unit depends on your house. If your house is built on a concrete slab, the unit is installed in the roof. If it has space underneath or a very low roof line, the unit is installed outside or under the floor. The ductwork, which connects the outlets to the heating unit, is neatly tucked away out of sight.

The heating unit draws air from inside your house into a return air grille. From here it then flows into the heater where it’s warmed, and then on to every room of your home via outlets, in the form of warm, gentle air.

Key Points

• Warm air flows through small outlets into every room you want to heat.
• Household Electrical heating appliances produce three times more greenhouse gas emissions than ducted gas appliances.
• The most effective and inexpensive way to power any heater is natural gas.
• Ducted central heating can heat your whole home.