Airflow performance is a major factor in how well your home’s ducted heating and cooling systems work. Aussie research shows that airflow problems can make your energy bills go up, reduce how comfy you feel in your home and even shorten the lifespan of your heating and cooling gear. Since heating and cooling systems make up such a big chunk of the average home’s energy use, even a bit of airflow restriction can lead to the system using more energy than it needs to.
The problem with airflow is that it can creep up on you gradually through all sorts of things like duct leaks, poorly balanced systems, clogged filters or bad design. Getting to know what causes airflow problems and what you can do to fix them is key to keeping your heating and cooling working like clockwork all year round.
Duct Leakage and Wasting Conditioned Air
You hear it all the time, duct leakage is probably the #1 airflow problem in Aussie homes with forced-air heating. Studies have shown that supply duct losses can be a whoppin’ 23% of conditioned air before it even makes it to the rooms where you need it. This means that your system has to run for ages to get the temperature right. It uses a lot more power and costs you a pretty penny in the process.
Pros use pressure testing and airflow gadgets to track down leaks and they’ll often do a visual check of the joints in your ducts. When we do a new ducted heating and cooling installation Malvern, our technicians will always check the ducts to make sure they’re good to go before we even switch the system on. If there are any issues, we’ll use special sealants to fix the joints and make any other repairs needed.
Poor Airflow Distribution Between Rooms
Some rooms in your home can feel like saunas while others are freezing. The reason for this is usually that the airflow resistance is different in each room. What can happen is that rooms that are closer to the indoor unit get too much airflow. The rooms further away get too little.
Clogged Filters and Restricted Return Airflow
If your return airflow is reduced, your system is going to work a lot harder and use a lot more power to try and get the job done. A clogged filter can actually make the system work really hard because it increases the static pressure needed to move air through the system. Data from the HVAC industry shows that a clean filter should only drop the pressure by about 0.10 to 0.20 inches of water column, but a filter that’s all clogged up can cause a lot more pressure drop.
Crushed Kinked or Damaged Ductwork
Flexible ducting is a bit of a fragile thing. It can get knocked around while maintenance and renovation work is going on. People in the industry have noticed that a bad kink can knock airflow by up to 50% or more in a room and even a small bend can cause problems by increasing resistance in the ducts and putting more work on the fan.
When professionals have a look around you might see them using a camera to peek at the roof space duct runs. You might see them getting up close and personal to see if any of the sections are compressed or if the ducts have come loose or if the insulation is damaged. If they do find some damage they may need to replace the faulty bits, sort out the supporting structure, and maybe even reroute the ducts a bit to get the airflow right again.
Incorrect System Sizing and Excessive Static Pressure
It’s not just physical damage that can mess up airflow. Sometimes the system just isn’t designed to keep up with the demands of the house. Get it wrong and you’ll have ducts that are either too big or too small and that creates a lot of pressure which in turn increases wear on the equipment.
Air Leakage in the Building Envelope
The state of the building itself has a big impact on airflow performance. If the place is not very airtight then it’s going to cost you. Research from the CSIRO found that poor airtightness can bump up household energy bills by up to 20% just due to all the unwanted air movement. Older Australian homes can be pretty leaky. We’re talking air leakage rates of over 30 air changes per hour at 50 Pascals. Those high-performance homes are the ones that do really well under the same conditions. They manage to keep it really low. Less than 1 air change per hour.
