It's not recommended to do this. It's worth calling out this piece of advice from a Houzz forum discussion – if you see a return duct that can accommodate a 2 inch or 4 inch air filter, but has multiple 1 inch filters stacked on top of one another to fit the slot, get rid of this setup immediately.
In conclusion, while the idea of stacking two filters might seem like a shortcut to better air quality, it can lead to more harm than good.
The most common problem you will face with a backwards facing filter is simple inefficiency. If your furnace is forced to blow air through the non-porous end of a filter, it will take more energy to do so. The blower will be overworked and you will pay more money for your heating.
You need 1 “set” of filters, 1 filters air intake to the blower unit & 1 on the return to filter house air.
Essentially, most homes will have at least two air filters, because most homes have a return duct to go along with their air handler.
While return vents don't always require filters, adding them provides additional filtration, improving indoor air quality and keeping dirt and debris out of your system. However, there are pros and cons to consider.
For 1- to 2-inch filters, replace them every 1 to 3 months. For 3- to 4-inch filters, replace them every 6 to 9 months. For 5- to 6-inch filters, replace them every 9 to 12 months.
Because the air handler filters have more filter material by virtue of being larger, they can collect and hold more dust, pollen, and smoke before they need to be changed.
Having a number of return vents (preferably one in every room, but also 2 or three is far better than just one) creates regular air pressure. If you have one return vent, your house is great. Maintain the doors to every room open so air can properly flow.
Yes, you can put filters on AC vents, and it is a relatively simple process. Most modern HVAC systems are designed to accommodate filters, making installation hassle-free. However, it's essential to use the correct filter size and type recommended by the manufacturer.
The direction of airflow in the HVAC system can cause some confusion, and for good reason too! To ensure your furnace filter is put in the correct way, make sure the arrow on the furnace filter is pointing towards the furnace.
Check for manufacturer instructions, and if there are no arrows, the air typically flows through the side with the metal or wire mesh. Always refer to the manufacturer's instructions if you're unsure about the correct installation for your specific filter.
For air conditioners with a reset button
Hold the reset button down for 3 seconds and leave. If it doesn't work, repeat the step. If it doesn't work even then, go to your circuit breaker panel and flip the switch connected to your Ac.
Remember, stacking filters should be done with caution, as it can introduce unwanted effects like vignetting, especially with wide-angle lenses. Also, stacking can reduce overall image quality due to additional glass elements in front of the lens.
Technically, you can temporarily run a furnace without a filter. However, it's important to emphasize the word “temporarily” here. Running a furnace without a filter overnight, for example, isn't likely to cause problems, but you should never allow this to turn into a long term solution.
Double filters significantly reduce the air flow, which directly impacts performance. Every filter has a resistance rating, higher MERV ratings mean more air filtration, which sounds great, but increases the air resistance, especially when they start to get dirty.
However, most HVAC contractors use a rule of thumb to determine the number of air vents needed. For example, for a standard residential HVAC unit, you'll generally need one supply vent and one return vent for every 100 to 150 square feet of living space.
Can You Have Too Much Return Air? Too much return air coming through your system isn't much of an issue because the fans and ductwork working to get that air back into the system only pull with so much force to make the HVAC system work correctly.
What room should return air ducts not be installed? Return air ducts should generally not be installed in rooms with high humidity or areas prone to moisture accumulation, such as bathrooms or kitchens.
Yes, an HVAC system can have two filters.
What problems can a backward filter cause? The most common thing you will notice is the inefficiency of the filter. It will be harder for the air to flow, which would take a toll on your system. More strain means spiked utility bills.
The filter belongs on the return side of your HVAC's furnace and AC system. It's a “must” to have one there. And if you have a return air filter of the right size that is properly installed, then there is no need for a supply vent filter. In fact, it will cause more problems than you might realize.
Expensive air filters are made from higher-quality materials, like fiberglass, that can last for up to 12 months. This not only saves you money, but it's also more convenient since you won't have to remember to replace your air filters as often.
Air filters that are overdue for a change are a common cause of HVAC system failure. Over time, dirt builds up in the heating and AC filters, causing components such as the motor to go into overdrive, which may eventually overheat your unit.