Often times houses will have some areas that are consistently warmer or cooler than other rooms, which is undesirable in most cases. First of all, the problem can’t be resolved by moving the thermostat to the area that is not keeping the desired temperature. That area would now be ok, but where the thermostat was is now the wrong temperature, because the problem is an air balancing problem, not a control issue. The answer is to adjust the supply registers to change the amount of air at different locations until an adequate temperature balance is reached.
NOTE: The amount of air you feel coming out of the registers is typically an unreliable way to balance, as the registers and ductwork are sized according to the size of the room, insulation, and outside exposure. The best method is to go by temperature as described by the following procedures.
In heating mode this is most effectively in accomplished colder weather. Start in the warmest room and close the registers down some, maybe halfway, then give the system a day to settle out. This will push more air to the cooler areas. Go again to the warmest room (likely a different room), and do the same thing. Continue this pattern until the temperature of the rooms is to your liking. You may need to revisit some rooms for some fine tuning. Theoretically, for rooms that wind up being the same temperatures, it should be ok for cooling as well. The exception may be a bedroom that you prefer to keep cooler for sleeping, that room may need little or no air in the winter, but you will be opening those registers in the summer to have the cooler sleeping climate.
For balancing in cooling mode do the same thing, but only in hotter weather and start in the coolest room first and continue working in the coolest rooms.
If you are unable to attain a desirable balance, as some houses can be difficult, one thing that will help this is to run the fan continuously by setting the fan control on the thermostat to “ON”. This will continue to circulate the air in the house in the off-cycle, constantly mixing the air in the ductwork and redistributing it. Your fan is designed to run continuously and has other benefits – your heating bills will be lower in the winter, your filter will pick up more of the dust in the house and if you have accessories on your system such as a high efficiency filtering system or humidifier, it will keep them active all the time. Remember, circulation is always a good thing.
Split level homes may be difficult to maintain even temperatures, and older two story homes that have inadequate ductwork to the upstairs will have cooling problems. Homes with open staircases can have problems due to the inversion of warm and cold air. This can be remedied by having a separate system for each level.