Heating and cooling costs can rise quickly during the peak seasons, and it’s understandable that many homeowners seek ways to lower those month-to-month expenses. But not all of the common strategies work, such as closing off rooms by shuttering vents and shutting doors. While it may seem intuitive that doing so will use less heat or cooled air and thus save you money, it actually increases your costs.
Increased Air Pressure
Closing vents seems like it would work since less conditioned air is needed for the closed-off room or rooms, but the traditional centralized HVAC system is not designed to benefit from it. The issue is static pressure, which in this case refers to the air pressure in your ductwork. All HVAC systems are designed to operate optimally within a certain static pressure range. Closing vents causes that static pressure to rise, and that can lead to a number of issues with airflow and the equipment itself.
Increased Energy Costs
Your air conditioner has a SEER rating and your furnace an AFUE rating, and these are both indications of the energy efficiency you can expect in ideal conditions. The ideal conditions include proper sizing of the HVAC equipment for the residence, ductwork that is sealed and unobstructed and static pressure within the appropriate range. As mentioned, when you close a vent, static pressure rises, and most systems run near their limit so it’s unlikely that you have much leeway. This causes the system to run inefficiently and ultimately leads to a higher electricity or gas bill rather than a lower one.
Increased static pressure affects your HVAC system in a number of ways. Consider that your ductwork is designed for a particular pressure range as well. As pressure in the system increases beyond the safe range, it can cause leaks to develop. A leak may even temporarily fix your problem since pressure in the system will be reduced. But you’ll be losing heated and cooled air. The leaks will continue to worsen over time, and your costs will rise as your system has to cycle longer than it otherwise would.
In a centralized HVAC system, pressure is what ensures that the conditioned air is distributed throughout the home evenly. As static pressure rises, airflow decreases. That can lead to airflow blockages. Reduced airflow results in uneven heating and cooling or what is often called hot spots and cold spots. A common mistake homeowners of dual-story homes make is closing vents on the second floor that is not used as much during the day, but doing so can actually make the downstairs area less comfortable.
Increased Maintenance Costs and Reduced Equipment Lifespan
Increasing static pressure in your HVAC system has costs associated with it that extend beyond your utility bill. When static pressure is too high, there is more resistance in the system. When static pressure is too high or too low, your system has to cycle for longer periods. Both scenarios lead to additional wear and tear on the system. The system will be more prone to needing repairs, and even if you schedule seasonal maintenance, you will likely shorten the lifespan of your equipment.
Closing Doors Can Have a Similar Effect
Closing doors can have a similar effect because doing so increases pressure in the home and also decreases airflow through physical obstructions. Industry research suggests that static pressure in the average residential HVAC system is too high and that closed doors may be part of the problem. That is not to say that you can’t close any doors in your home or that closing a single door is an issue. But unless you have a reason to close a door, such as for privacy, all doors should be open.
HVAC Zoning: A Better Alternative to Closing Your Vents
What people want to achieve through closing vents can actually be achieved in an efficient manner through what is called HVAC zoning. In a dual-story home, for instance, you could have an upstairs zone and a downstairs zone and a separate thermostat for each. You could keep the upstairs at a warmer or cooler temperature during the day, which would decrease your costs without comprising your downstairs comfort or having a negative impact on your system.
Variable-Speed Air Handler
There are a number of ways to achieve zoned HVAC, but the most common way currently involves the use of a variable-speed air handler or blower. Traditional HVAC systems have a fixed-speed air handler or blower. As the term suggests, variable-speed systems are able to increase or decrease the amount of air blown in order to maintain the optimal static pressure. Closing vents is still not a good idea even if you have a variable-speed system. Zoned systems typically have dampers within the ductwork that are coordinated with the thermostat and air handler to adjust pressure in a safe and efficient manner.
An alternative that would allow you to close your vents safely is installing additional ductwork. This additional ductwork would be there to take the extra pressure when needed. Such setups can be designed to dump the additional air, which is the less efficient approach, or reroute it back to the blower to be sent through the core ductwork again.
Multiple Heating and/or Cooling Units
Depending on the size of your home, it may be necessary to have multiple heating and/or cooling system in order to achieve the zoning desired. Some systems will make use of one or more mini-splits as well. Mini-splits are ductless systems but are effective for zoning and can be useful to extend coverage to areas that lack duct access, such as home additions, basements and detached garages.
The EPA estimates that smart thermostats can lower energy costs for the average home by 8%. Programmable thermostats work too but are prone to inefficiency through human error. Be sure to explore local resources as there are often rebates available that let you lower the initial cost and begin saving sooner.
Another way to save money over the long term is ceiling fans. Ceiling fans distribute the air in your home more evenly and allow you to run a cooler temperature in winter and a warmer temperature in summer. Ceilings fans cost much less to run than an AC or furnace and tend to pay for themselves over time.
Your Local Heating and Cooling Pros in Denver
Summit Heating & A/C is a locally owned and operated company that has served Denver and the surrounding areas for more than 80 years. Area homeowners can count on us for the installation, maintenance and repair of air conditioners, furnaces, heat pumps and mini-splits. We also install and service air filters and air purifiers. We even have expert plumbers that specialize in drain cleaning and repair, sewer repair and replacement, as well as tank and tankless water heaters. Call us today or contact us online to learn more about the services we offer or to schedule a consultation or service appointment.