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Why Is My Ducted Air Conditioner Not Cooling or Warming?

A frequently asked question:

“I have set my ducted air conditioner to 24 degrees but it never seems to get warm enough (or cold enough) in my Bedroom and the Living Areas”.

In a standard ducted system, you will have a Return Air Grille installed in the ceiling of your hallway. Inside this Grille is a little component called a Thermostat.  The Thermostat has a very important job – it senses the temperature of your house.

When your AC is running, ALL of the air coming out of your ceiling outlets travels up the hallway finding its way to the Return Air Grille.  As all the air is sucked into the Grille, the Thermostat measures the temperature.

Once the Thermostat reaches the 24 degrees (which you have set) – your AC thinks, “yes we made it!” and it automatically stops heating (or cooling).  Job done!

As you can see from this attached picture, there is a lot more warm (or cool) air in the hallway than any other room.

The air that comes out of each outlet in a room travels to the point where the return air grill is located. The grill is typically located in a hallway. As all the air pools at this end of the house before it is extracted, it then makes this section of the home feel warmer than the other parts of the house.

As the air is extracted through the return air grill, the temperature sensor then takes a reading and compares it with what the user has set, for instance, the standard 24 degrees. Once it senses that the desired temperature has been achieved, the inverter ramps down and the machine stops trying to produce more warm or cold air.

This means the Set temperature of 24 degrees will be achieved far more quickly in the rooms closer to the Return Air Grille than the rooms at the further ends of the house.

So to achieve warmer temperatures in the other rooms, you may need to set a higher temperature than the recommended 24 degrees – as high as 28 degrees in winter, and for cooling even as low 19-20 degrees in summer.  Obviously, this all depends on your comfort level.

To help with the temperature difference between rooms, the installation of zones is recommended.

When trying to heat or cool the living areas, closing the bedroom zones and doors forces the Return Air to be drawn from the living areas and helps achieve a temperature closer to your Set Point (see diagram).

For even more accurate temperature control in individual rooms, the installation of a My Air 5 system allows an individual room sensor to be placed in each room and allows you to set individual temperatures for different rooms in your house.

If you have other concerns about your ducted air conditioning system, feel free to contact the experts at Cold Front Air Conditioning.

“With the onslaught of these EXTREME TEMPS and the DEMAND FOR INSTALL we were very impressed with how QUICKLY and EFFICIENTLY Cold Front were to slot our job in”