People often want to know if they can change their existing ducting system to A new reverse cycle air conditioning system (HVAC) by using all the same ducts and outlets. The simple answer is no. Below is a list of reasons why you can not simply change the system to become a reverse cycle system (HVAC).
First, reverse cycle gates (or exit points) are usually placed near Windows and away from doors. This allows the air to condition the heat / cold that comes directly through the windows. The airflow for a reverse cycle system should also move the longest path from the outlet to the return air grid. If a plug was placed next to a door, the air would simply be sucked under the door to the return air grille and the room would have hot spots near the window.
The problem with evaporation grids is that they are usually located near doors. The airflow of the evaporative units should take the longest possible path in a room and out of the window. If they were located right next to a window, air was simply flowing through the window and hot spots would be caused near the doors and the other side of the rooms.
Due to these reasons, it is not advisable to place the reverse cycle grids in the same location where a channeled drainage grille was previously located. While it is possible to do so, this will greatly reduce the efficiency and capacity of the system. The best option is to start again and place the new reverse cycle grids in the desired location if necessary. However, this would mean that you should repair and paint the holes in the ceiling left by the removal of old evaporating grids and this can be an expensive job.
Another option would be to add additional grids as needed. You may consider leaving grids near the doors of the evaporating system and adding extra grills through the windows if necessary.
Another problem encountered when exchanging systems is that the old pipeline can not be used. The ducts used for evaporative units are much larger than those required for reverse cycle air conditioners. The evaporative units use pipes around the 16-20 inch mark. This large duct is used by evaporative air conditioners because the air blows extremely quickly and aims to draw in air up to 40 times the cubic area of your home per hour. The reverse cycle channels are usually only around the 12-inch diameter mark. This is due to the fact that reverse cycle air conditioning is much slower than that of evaporative counterpart.
Evaporative pipes are usually only slightly insulated. Reverse cycle cables should always be insulated at least 2 inches to keep cooling / heating and prevent condensation from occurring.
So if you want to swap your current evaporation system on a new reverse cycle system, you are best to start from scratch. Make sure you get some quotes for the cost of patching and painting the ceiling before you start any work. And if the air conditioning contractors tell you that they can simply exchange a system using the existing conduit and outlets, ask a lot of questions and be careful as they may not be there to help you when You have paid a lot of money and your system is not working.
In some cases, using existing grids may be an option, but this would make the system less efficient.