Why is off-cycle heat loss greater in older less efficient units compared to new high-efficiency ones?

The reason off-cycle heat loss is greater in older, less efficient units compared to newer high-efficiency models is linked to the design and condition of the heat exchangers. In older units, heat exchangers tend to be wider and may not fit as snugly as newer models, which increases the likelihood of air leaks. These leaks allow heated air to escape and cold air to infiltrate, leading to significant heat loss when the unit is not actively heating.

Newer high-efficiency units are designed with improved technologies that minimize air leakage and often include features that enhance thermal insulation and reduce off-cycle losses. The materials and designs used in modern units help maintain the heat within the system, effectively minimizing energy waste and improving overall efficiency during both operation and off-cycle periods. The combination of more precise engineering and better materials in modern systems leads to reduced off-cycle heat loss compared to older, less efficient units.