There is a religiously believed and also practised myth and that is; in order to save energy, close registers in the unused rooms. The fact is, doing so not only badly affects the HVAC system and the ductwork but also creates some very bizarre indoor air quality and air flow problems. We as HVAC specialists suggest homeowners time and again not to close their registers in the hope of saving energy or keeping some rooms overly cold/warm. It needs to be understood that the HVAC system does not work solely on its own and the same is true for the ductwork. Both work in coordination with one another. Disturbing one simply means disturbing the other as well. Below, we discuss in detail why closing registers in unused rooms is not a good idea at all.

- Energy saving? No such thing happens dude 

The heating/cooling temperature is not determined by the registers. It is determined by the thermostat which you set at whatever temperature you want the indoor to be. In that case, the HVAC system will continue to operate until it reaches that temperature. The HVAC system does not know whether the registers are opened or closed. So there's no energy saving at all. The system runs for as long as it usually does.

- Comfort compromise 

While the registers are closed to attain more comfort, doing so actually increases discomfort. This happens when the airflow is disturbed. The supply of airflow is not affected by closing the registers. It is in fact controlled by the dampers present within the branch ducts. So the airflow goes all the way to the opening and finds it closed. Since the air does not find a way out from the duct, it returns and this return disturbs the air flow in the rest of the rooms as well, resulting in discomfort or hot and cold spots.

- Pressure problems  

Homeowners close supply registers but the return resisters remain open. This way the air from the room where there is no air supplied keeps on evacuating creating a negative air pressure in the room. With a negative air pressure created, the room tries to suck air from the outdoor and does so by sucking air from holes and leaks. This affects the indoor air quality as the contaminated, unfiltered air from cracks and holes seeps in.

- Wear and tear problem 

Pressure is created in the ductwork which affects the dampers, the blowers as well as the supply registers which are closed. This increases the risk of wear and tear. In the case of foil ductwork, the ductwork may develop massive leaks.

Keeping the above-mentioned consequences, it can be deducted that closing registers offers no genuine benefit. Even the benefits for which the registered are closed are not actually received. So if you have been practising closing registers, do it no more. Neither your energy bills are getting any effect from that nor it does any help to add to the comfort level. Better try genuine ways to improve airflow and air quality.

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