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RidgeLine's home maintenance 'How To' blog. Search the Categories on the right for articles to help solve your problems.
Warm weather is just around the corner and before you turn your air conditioner on it’s time to change the filter. While your air conditioner is off take out the filter, write down the size, and head to the hardware store.
If you walk down the filter aisle at Lowes, Home Depot, or Menards the first filters you will see are high end ones that promise to filter just about everything. Most people have a 1” thick filter so most filters on the shelves will be 1”. All these wonderful filters use a rating system called MERV. MERV stands for Minimum Efficiency Reporting Value and it’s a standardized value so you can compare filters. The higher the MERV, the better the filtration. The highest MERV you’re likely to find on the shelf is 13. At MERV 17 you’re getting into HEPA filter range. HEPA filters were originally developed by the military to remove super fine particles that had become contaminated by radioactive material. I guess that means they're good enough for your house, right?
Like many people I wandered down the filter aisle wanting to get something nice. So, I came home with this filter.
This was the low end of the nice filters with a MERV 8 rating. I also picked up the 8500 filter, which is MERV 11. Below the Basic 7500 filter were the cheap disposable filters with no MERV rating and no marketing materials for me to read. I figured those unnamed filters were junk.
After looking at the high MERV filters, I want you to put all of them back on the shelf and walk down to the generic filters with no MERV ratings or advertisements. These filters will probably say disposable or something similar (apparently the high MERV filters that get thrown out just as often aren’t ‘disposable’). You want a cheap filter.
All the advertising about filters seems to have nothing to do with what your air conditioner needs. The advertising has everything to do with what you’re afraid of. Mold. Bacteria. Smoke. Oh My!
Your central air conditioner needs two things. First, it wants a good supply of air. All of the high MERV filters restrict air flow beyond what your air conditioner wants. After a little dust builds up on the filter it restricts air flow even more. This summer if your air conditioner stops working the first thing you should do is check to see if the air conditioner has iced up. Without a sufficient flow of warm air blowing over the evaporator coil in your air conditioner ice can start to build up. As more and more ice builds up the air flow is reduced even more in a kind of snowball effect, literally.
Icing up can also lead to excessive moisture in your air conditioner. When the thermostat turns off the air conditioner any ice that is on the evaporator coils will melt. At this point it is possible that mold or bacteria can start to grow, especially if this freeze-thaw cycle is happening consistently. The mold or bacteria can start to make your house smell in what is actually dubbed “Dirty Sock Syndrome.” No joke. Google it.
The second thing your filter needs to do is remove the large particles and contaminates from entering the air conditioner. Pet hair and large particles can attach themselves to the inside of the air conditioner clogging up and reduce the unit’s efficiency. All those particles in the air conditioner are food for bacteria and mold if they are not filtered out. The fine particles don’t really affect the air conditioner because they stay airborne and pass through the air conditioner. So a high MERV filter does not help the air conditioner function better.
What we need is to find the right balance between airflow and filtering. Many manufacturers recommend using the cheap blue fiberglass filters. These filters meet the filtering and airflow requirements for central a/c units.
Despite the airflow problems that high MERV filters can cause some people need their air filtered for health reasons. Allergies are possibly the most common reason. I sympathize. I have allergies and admit to coming home, closing the windows, and turning on the air conditioner to help get rid of the pollen in the house. I don’t care what the scientists say, it helps.
Even worse than seasonal allergies is asthma. Asthma can be brought on by pollen, mold, dust mites, or smog. High MERV filters can filter particles this small so putting a high MERV filter in your central air conditioner makes sense. But it’s wrong.
Here’s why. Your central air conditioner’s blower fan moves enough air to completely circulate the air in your house around 7 times when it’s running. If your air conditioner blower fan only runs 15 minutes every hour then you’re only completely circulating the air in your house a little under 2 times. In order to really control the air quality of your house you need to completely circulate the air around 15 times an hour. High MERV filters are not significantly effective because the air conditioner does not move enough air.
I ran my MERV 8 filter for about 6 months during last winter and here is the result.
On the left you can see the overall filter with no large particle debris. On the right is a closeup of the filter and you can see a little coating of dust. This dust was most certainly restricting the air flow of the filter. I also want to point out that the amount of dust on this filter is about the same amount of dust that settled on one of my ceiling fans! So, it did not significantly remove more dust from the air than what settles out naturally in my house.
I should confess though, that I have seen filters that were horrible covered in debris after 6 month use. It depends on your house, if you have pets, how you live, etc.
If you have health issues and really want to affect the quality of your indoor air for the positive you can do two things. The easiest is to use a spot HEPA air purifier. These little machines are not big enough to handle your house, but studies indicate that when they are directed over your bed while you sleep they can relieve allergy and asthma symptoms. Air purifiers start at about $100 for something large enough to handle a small bedroom. Here are some examples available from Menards.
The second option is to install a Heat Recovery Ventilator (HRV) with a HEPA filter. HRVs work by diluting contaminates in the air. The HRV pulls air out of your house while bringing fresh air in from outside. HRV units cost hundreds before installation labor for a small unit. HRVs designed for entire houses run over $1000. Here is an example of one made Broan. I don't endorse the model because I've never used it, but the information will give you some ideas.
Back to filters.
Many furnaces have 1” thick filters. However, the recent push has been to start using thicker filters. The benefit of a thicker filter is that they have more surface area for air to be sucked through. This causes air speeds through the filter to be reduced which in turn lowers the air resistance.
The common 1” pleated filter also comes in a 2”, 4”, and 5” version. The 2” filter is not much of an upgrade to be honest. The 4” and 5” filters do start to see better air flow at higher MERVs.
You can go even bigger with a whole house purification system that looks like a super wide electronic version of the 4” filter. Here is an example made by Honeywell. These systems can work quite well if the blower fan is run more often. There is a setting on thermostats that allows you to turn just the fan on. Instead of circulating the air in your house only 2 times, leaving the fan on can get you closer to circulating the air in your house 8 times an and hour. Now you can start to make a difference, but it comes at a high price.
So what’s the best 1” filter for your central air conditioner if you don’t want to size up? That’s a tough question but we can narrow the selection down to two options. First, the cheap blue fiberglass filters are a decent choice if you’re primarily interested in the efficiency of your air conditioner and you don’t have health issues. If you want a little more filtration a pleated filter up to MERV 8 is an ok choice. At MERV 8 many, but not all, pleated filters really start to restrict air flow like a high MERV filter. If purifying the air in your house is a major goal you’re going to need to spend some money and look at options other than a 1” filter.
Before you turn your air conditioner on this year, make sure you change the filter. Realize that air conditioners are more sensitive to reduced air flow than furnaces. All the hype about 1” filters being able to purify the air in your house is overblown. Filters are meant to protect your air conditioner, not purify the air in your house. If you want to purify the air in your house do it right. As for your central air conditioner, don't feel guilty for buying a cheap filter. A cheaper filter changed regularly is the best decision for your air conditioner.
We all know about the importance of furnaces and hot water tanks. How could we forget them? We quickly discover when they stop working. The most important appliance people forget about doesn’t remind them when it stops working. Some homes don’t even have them. Forget this one appliance and your house can smell. Forget this appliance and your health, especial your children’s health, can be problematic. Forget this appliance and you're inviting mold. . . and insect infestations. Forgetting to install and run a dehumidifier in your basement can create a sick house.
Many times people think dehumidifiers are only necessary in leaky basements. And while it is true that dehumidifiers rarely run during the winter in Ohio, they are absolutely necessary once it starts warming up outside. Cleaning and maintaining your dehumidifier should always be near the top of your spring cleaning list.
So what makes a dehumidifier so important? It’s all about relative humidity. Relative humidity is the amount of moisture air can hold at a particular temperature. Hot air holds more water than cold air. You know how we often get dew in the spring mornings? Dew happens because as the air temperature drops at night less moisture can be held. When the temperature goes down while the amount of moisture in the air remains constant, the relative humidity percent increase. At 100% relative humidity moisture starts to condense which is when dew occurs.
Molds and insects love dew. But, they don’t actually need liquid water like dew to survive and grow. High air moisture levels (also called high relative moisture) is sufficient for mold and insects to thrive. InterNACHI along with Jeffery May, author of My House Is Killing Me, recommend keeping relative humidity levels to between 30% and 50%. The sweet spot is 50% relative humidity. Below 30% humidity people can start to develop sinus problems. Above 60% and molds start growing. The InterNACHI chart below shows why 50% humidity is the best goal.
Ideally your humidifier should empty directly into a floor drain or pump. In my house, the dehumidifier drains directly into the condensate pump from the furnace and A/C. Wilken Sheet Metal set this up for me when they put in a new HVAC system a few years ago. I set it at 50% humidity and let it run.
Two things are required to keep this system running. First, the filter on the dehumidifier needs cleaned to keep maximum airflow. Second, the pump reservoir needs cleaned out.
You can see a lot of slim growing in the bottom of my condensate pump. Standing water like this can foster bacteria growth more so than the typical molds we think of. When you clean out your pump make sure to use a disinfectant so things don’t grow back as fast.
Dehumidifiers also help prevent one of the most likely causes of indoor allergies. At above 50% relative humidity dust mites start to flourish. Dust mites are soft bodied microscopic insects that require moisture to stay alive. They can live off high humidity or the moisture our bodies give off. Most allergies to dust mites come from their fecal pellets. These pellets often become airborne as we disturb surfaces in our homes. As you sit down on your couch air is expelled from the cushion, along with dust mites and dust mite fecal pellets. While the fecal pellets and dust mites are airborne we can unknowingly breathe them in. Keeping the humidity low is the best cure for dust mites.
Dehumidifiers are often overlooked as a necessary appliance. Humidifiers get all the attention but dehumidifiers keep you and your house healthy. Keeping 50% relative humidity in your home keeps your home healthier by preventing mold, insects, and allergens. As part of your spring cleaning make sure your dehumidifier is in good working order and set to 50%.
Dryer vent maintenance is one of the last things on my very long list of to do’s. While doing laundry this weekend I noticed my dryer vent was not heating up very fast so I went outside to check the vent.
According to the U.S. Fire Administration’s Clothes dryer fire safety outreach materials, 34 percent of the 2900 fires and 5 deaths were caused by lint buildup from not cleaning. One sign of lint buildup is a dryer that takes a long time to dry. I guess it's time to get out some tools and check my vent.
Thankfully my dryer vent is relatively short so it probably won’t require any specialized tools. A long handled brush will do. If you have a longer duct system or long sections of duct that need cleaning you should invest in a duct cleaning brush. Brushes are fairly simple like the Deflecto Dryer Brush. There are a variety of brushes that you can get through your local big box store.
If you’re buying a brush to clean out a flexible duct that has ribs on the inside instead of being smooth, don’t. Throw your duct in the trash and buy new smooth ducting. The ribbed interior catches more lint and thus clogs quicker. Plus, it’s more likely to get kinked when slid back into place.
Use rigid metal instead. Also, forget the screws. They are great at catching lint inside the ducting. After sliding my dryer out and dismantling my duct, here’s what I found.
I used my long handled nylon brush to scrape the lint off the inside of the duct work. You have to scrape the lint with a brush because it is sticks to the inside of the pipe. It won’t fall off. It can’t be vacuumed out. After cleaning my duct I have one more step before putting everything back together.
While the dryer is out and the vent is off I need to use this opportunity to vacuum out the back of my dryer. Get as much lint as you can see.
The last thing to do is cleaning out the dryer vent cover shown in the first picture.
It’s time to put everything back together. Be sure to connect your ducting in the right direction. The first section from your dryer slides into the second. The second section slides into the third, and so forth until you're connected to the dryer vent cover. When sliding your dryer back in place be careful not to damage any duct. When my dryer was originally slid back in place the metal duct was dented. These dents caused severe buildup of lint inside the duct.
After I was all done I turned on my dryer and went outside to check the vent. I could tell immediately that my dryer was pumping out a lot more air.
The U.S. Fire Administration advises cleaning your ducting every three months. When ducting has lint built up inside, your dryer will start to seem like its taking longer to dry your clothes. So, if you notice your dryer is not working well, check for lint. Finally, be sure to clean the lint filter after every load. Cleaning your lint filter is the number one way to keep lint out of your dryer and duct work. A little maintenance can go a long way to prevent common problems.