As either a past or current gas heater user, you might wonder about the differences between your gas heating system and a reverse-cycle air conditioning system. This guide will help you understand how these systems typically work and why you might experience different performance levels, especially during winter.
Gas Heating vs. Reverse Cycle Heating: The Basics
While both systems provide heating, they work in fundamentally different ways:
Gas Heating
A gas heating system:
- Uses combustion (fire) to generate heat;
- In most cases, produces heated air quicker than a reverse cycle air conditioning system upon start up;
- Heating output is not affected by outside temperature; and
- Only provides heating compared to a reverse cycle air conditioning system which provides both heating and cooling.
Reverse Cycle Air Conditioning
Most reverse cycle air conditioning system:
- Uses an electric heat pump to transfer heat;
- Provides both heating and cooling in one system; and
- Generally, its performance can be affected by outside temperatures.
Why Might Reverse Cycle Air Conditioning Feel Less Effective in Winter?
- Heat Transfer Process: Most reverse cycle systems draw heat from the outside air and transfer it indoors. In colder temperatures, there’s less heat available to extract, which can generally result in:
- Less heat output; and
- Longer heating times.
- System Capacity: The correct system capacity (measured in kW) is crucial for optimal performance, especially in colder climates. A Licensed Professional should be able to inform you of the most suitable heating capacity after assessing a number of factors, including the capacity differences, and the size and insulation of your home and the room.
- Defrost Cycles: Depending on the capacity and type of your reverse cycle air conditioning system, cold temperature conditions often require the reverse cycle air conditioning system to run defrost cycles. This is a normal part of the operation but can temporarily pause heating, which may be noticeable to the user
Understanding Defrost Cycles
Defrost cycles are not a fault but a necessary process for reverse cycle air conditioners operating in cold conditions. Frost and ice can develop on the outdoor unit during normal heating operation, which reduces the system efficiency. The system will perform a “defrost” to melt the frost and ice on the outdoor unit to increase system efficiency.
For more detailed information on defrost cycles, you can refer to the following resources:
- Mitsubishi Electric: Air Conditioning Defrost Cycle
- Mitsubishi Electric Blog: All You Need to Know About the Defrost Cycle
Making the Switch from Gas Heating to Reverse Cycle Air Conditioning
When replacing your gas heater with a reverse cycle air conditioning system, proper system sizing is crucial for satisfactory performance. Although testing parameters and results vary by users, here’s what you need to know:
Understanding Heating Capacity
The heating capacity of your system is measured in kilowatts (kW). To ensure your new reverse cycle system performs adequately:
- We recommend getting a professional heat load calculation to determine your exact heating requirements
- A qualified air conditioning specialist can perform this calculation
- The specialist can determine the appropriate kW rating needed to heat your space effectively
A Heat Load Calculation considers various factors to determine a space’s appropriate air conditioning capacity including, but not limited to the geographic location and climate of the user, which would impact the heating and cooling demands;the user’s building’s orientation, construction materials, and insulation quality which affects heat retention and loss; and other key elements including window and door sizes, ceiling height, and physical dimensions of the space, which affect the total air volume requiring temperature control.
Occupancy levels, lighting, and appliances also contribute to internal heat gains. In most cases, assessing these factors will allow a more accurate Heat Load Calculation which ensures that the selected air conditioning system is neither under powered nor oversized, leading to optimal efficiency, comfort, and longevity.
Choosing a Qualified Specialist
It’s essential to work with a properly licensed professional. Look for specialists who hold:
- A full/unrestricted Refrigeration and Air Conditioning (RAC) Licence
- This licence permits work on any air conditioning system, including split systems, regardless of cooling capacity
- A full/unrestricted RAC-licensed professionals are qualified to handle all aspects of:
- Installation
- Servicing
- Repair
- Maintenance
- Decommissioning of air conditioning units
Why Professional Assessment Matters
A professional heat load calculation is recommended because:
- It ensures your new system matches your heating requirements
- Prevents under sizing, which can lead to poor heating performance
- Helps avoid oversizing, which can result in energy inefficiency
- Takes into account factors specific to your home and climate