Question

Does it make sense for a two story house with 2 HVAC units that each unit zoned for one floor, that to set heat for second floor and cool for first floor when it’s 79F outside in May? What would happen to the HVAC unit if someone does that?

Answer 1

Setting the heat for the second floor and cooling for the first floor simultaneously when it's 79°F (around 26°C) outside in May would create a situation where both HVAC units are working against each other. This can lead to several issues and inefficiencies:

1. Energy Waste: Running the heating and cooling systems simultaneously results in wasted energy, as they work against each other to achieve opposing temperature goals. This can significantly increase your energy bills and reduce overall efficiency.

2. Strain on HVAC Units: Running both HVAC units at the same time and with conflicting temperature settings can put unnecessary strain on the systems. They may have to work harder than necessary to maintain the desired temperature conditions, leading to potential wear and tear on the components.

3. Comfort Issues: Running heating and cooling simultaneously may create uneven temperature distribution throughout the house. The two systems may end up competing, leading to hot and cold spots and an uncomfortable living environment.

4. Reduced Lifespan: The added strain and continuous operation of both HVAC units can shorten their lifespan, leading to more frequent repairs and replacements.

To avoid these issues, it's best to use each HVAC unit for its intended purpose. In May, when the outside temperature is 79°F, you should primarily use the cooling system for both floors. If there's a specific reason for needing heating on the second floor (such as a room that stays consistently colder), it's better to address the underlying issue, such as improving insulation or air circulation.

Using a zoned HVAC system allows you to control the temperature independently for different areas of the house. If you want to optimize comfort and energy efficiency, consider adjusting the temperature settings based on the usage and occupancy patterns for each floor.

In summary, it doesn't make sense to set heat for the second floor and cool for the first floor simultaneously when it's 79°F outside. Doing so would lead to inefficiencies, discomfort, and potential strain on the HVAC units. Properly utilizing the zoned system and setting appropriate temperatures for each floor based on the outdoor conditions and indoor needs will result in a more comfortable and energy-efficient home.