Furnace filters have fibers that prevent debris from entering the system. Manufacturers design furnace filters with the intention that air flows in one direction through the filter medium. That way, the filter does its job of preventing dust from accumulating on blowers and motors inside the furnace. While an occasional backward filter installation is not likely to cause damage to the system, it can cost you money in efficiency. Air Circulation The furnace pulls in cold air from the home, warms it through a heat exchanger, and blows the heated air back into the living space. Air in the home collects dust and fibers that could harm the internal components of a furnace. The filter prevents this from happening by collecting the dust and debris before it reaches those critical furnace components. Some filter designs even capture smaller particles, such as those that produce allergic reactions in people, in order to keep the living-space air as clean as possible. Furnace Efficiency The biggest problem with air filters that are installed incorrectly, is that the furnace has to work harder to do its job.

The same applies for central air-conditioning units, which typically circulate air through the furnace system. One side of the filter is more porous than the other. A furnace or central air unit that has to pull in air through the non-porous side of a filter loses efficiency because it runs longer, requiring more energy. The result is a spike in the utility bill. Air Filtration Air quality inside the living space also suffers when a furnace filter is installed the wrong way. The filter cannot capture dust particles as well when air moves through the filter in the wrong direction. That unwanted debris ends up floating in the home’s air instead of being trapped by the filter. Indicator Marks Most air filters have arrows printed on the sides that act as indicator marks that point to the direction of airflow. Whether furnace filters are located at the plenum inside the furnace cabinet, or at the cold air return near the ceiling, the arrows must point toward the furnace -- the direction of the airflow -- when installed.

If you have a service person install air filters for you, take a look at how she puts them in, and which way the arrows point. Check filters every month or so, and replace them when you can no longer see light coming through the filter. ac not cooling ice on unitA dirty filter also decreases furnace efficiency, and contributes to poor indoor air quality. carrier ac unit costsReferences Cool It Heating and Air Conditioning: What Happens if You Put Your Air Filter in the Wrong Way?split systems ac unitsThe Family Handyman: How to Change a Furnace FilterDesign Comfort: What Happens if You Put Your Air Filter in the Wrong Way? Photo Credits Comstock Images/Comstock/Getty Images Suggest a CorrectionIt doesn’t matter if it’s an apartment, bedroom, office, garage or classroom – sometimes you have a space that you really, really need to cool down, and that old desk fan just isn’t cutting it anymore.

It’s time to upgrade to a window air conditioner…but what kind? Luckily, today’s window-based AC units are smarter and more efficient than ever, and we’ve collected the best of the best for you to choose between.BTU stands for British Thermal Unit. If your chemistry lessons are a little hazy, BTUs are used as shorthand for describing how much heat energy is being moved around. For reference, one BTU is roughly the same energy as lighting a single match. The higher the number of BTUs on an air conditioner rating, the more easily it can cool a space by moving that heat elsewhere…and as a result, higher BTU units can cool larger spaces. However, moving a lot of BTUs requires a lot of electrical energy as well, so higher BTU numbers mean higher AC bills.AC manufacturers skip the science lesson and just recommend square feet of a room, but this is only a guess. If you really want to know how many BTUs to look for, you can find your cubic space and learn the required rating . GE Aros Smart Air Conditioner 8,000 BTUs ($235)

The rise of the digital home and Internet of Things has given us plenty of options for smart thermostats (looking at you, Nest), but what happens if you want a less-central air conditioning option for your window? You can turn to the GE Aros, which in fact does act a bit like the Nest thermostat. It can track your habits and automatically adjust to cool the room based on the day of the week so you end up saving more money. It also includes an ability to track your location via your phone’s GPS and turn on or off when get to/leave your home. And, of course, you can control it remotely with the app. Retractable wings and touch-button controls are included –this also model includes three cooling modes as well as three fan speeds for its upward-facing vents. Those vents are the only major downside, since they don’t really allow for any airflow direction control. Buy one now from: LG LW8016ER 8,000 BTU ($220+) This powerful LG model has a 12.1 efficiency ratio according to the Energy Star guidelines, a rating that should guarantee you some energy savings if you are switching from an older model.

This window unit is rated for up to 340 square feet, and includes three cooling modes and three fan speeds. It can also provide two directional air currents, and allows you to set a time or use a remote control – not exactly smart tech, but still nice when it comes to programming. The unit requires a 115-volt outlet…a common requirement for window units, which means that any average North America wall outlet will work fine. This isn’t an issue for any of our chosen units, just make sure there’s an outlet near the window you want to use. Friedrich CP05G10A 5,450 BTU ($262) This is a less powerful air conditioner designed for smaller rooms: It’s able to cool around 150 square effectively, which makes it an ideal bedroom unit. There’s an energy saving feature that makes sure the fan is only running when the unit is actively cooling, as well as a 24 hour timer for programming. You can choose to customize the 4-way airflow in the direction you want it most, as well as choose between operating modes for cooling, dehumidifying, and more.

Noria 5,000 BTU ($300) Noria is a unique case when it comes to window air conditioners. This model made the rounds on crowdfunding sites and immediately earned a ton of money thanks to its unique, extra-small design that can fit on normal windows or smaller windows with less room. It has plenty of smart tech that allows you to control and schedule the unit from your phone, and a fresh air mode that you can turn on to bring cool air from outside during the evening. This innovative little device is rated for up to 160 square feet and only weighs around 30 pounds. The MSRP is $400 but you can still get it for $300. Frigidaire FFRA0511R1 5,000 BTU ($119+) This very popular window air conditioner hits a sweet spot when it comes to price and usability. It’s rated for a 150 square foot space, and has a fairly high energy efficiency ratio of 11.1 to help you save some money. There aren’t quite as many customization features as some of our other models, but you still get two cooling speeds and two fan speeds, as well as 2-way directional airflow.

It’s a solid set of features in a compact package that can work great in many “I need to get this room cooler now” situations. Haier ESAQ406P Serenity 6,050 BTU ($270) This is one of the more expensive AC units on our list, and not just because it can cool an area up to 250 square feet. It also includes more modes than most units – four different settings for 1)cooling, 2)using only the fan, 3)saving as much energy as possible, and 4)dehumidification. There a dual motor and cross flow design for more accurate air control, and a timer for schedules throughout the day. If noise bothers you a lot when trying to sleep, consider this model: It’s been rated as one of the quietest AC units around. Frigidaire FFRE1033Q1 10,000 BTU ($299+) Finally we come to the big option – this unit can handle up to 450 square feet of space, making it ideal if you don’t so much want to cool down a room as you want to drop the temperature in an entire apartment or loft (the size also makes this a great unit for dehumidifying at a rate of three pints per hour).