HVAC is probably the biggest energy drain in any house. This leads to a higher energy bill every month when the furnace or the AC is used a lot. Keeping your heating and cooling systems running efficiently is a good way to keep the energy costs down.

Efficiency going down can also be an indication of larger issues. Such issues if left alone could end up costing a lot more eventually.

It is a good idea to see if the heater or the AC is working well. One simple way that doesn’t require any complex instruments is by taking the temperature at the vents. Vents are where the air from the HVAC system is pushed into the house.

There are 2 types of vents: a return vent and the register. The return vent is from where the air in the house is pulled into the HVAC system. This air is then cooled (or heated) and pushed into the house through the registers.

You can tell which one is the return air and which one is the register by looking at their coverings. The return air generally can’t be closed whereas the air coming through the registers can be directed or closed using the lever.

Take the temperature differential

To begin, let the AC run for 15 minutes. This will give the AC enough time to get started and start pushing in cooled air through the registers.

First take the temperature at the return air. This is the temperature of the room/house.

Now take the temperature at one of the registers. There should be a 15-20 degree temperature differential between the 2 temperatures.

If the temperature differential is less than 20 degrees, then this means that the house isn’t getting cooled and the HVAC is simply moving the air around.

Between 15 and 20 degree differential means that the air conditioner is working well.