How to extend the life of your HVAC system

Checking air filters at least every two months and changing them when needed prolongs system life. EPA suggests using the highest-quality filter recommended by your manufacturer.

The National Air Duct Cleaners Association says not to skimp on price; better filters block more particles and last longer than cheap ones.

"You can go to the hardware store and choose between a good $20 filter or a blue stringy one for 69 cents," Sheppard says. "You can practically see right through them. Our guys call them bowling-ball catchers, because smaller particles are going to blow right through."

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Cleaning your air ducts on the regular will reduce excessive dust. (Photo courtesy of Angie's List member Edward S.)
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The statement that a dirty air filter makes the blower motor work harder is misleading. The amperage drawn by the motor is a result of the work it does, i.e. move air. A clean filter allows the blower motor to run at maximum efficiency because more air moves. A higher rated filter will catch more dirt and reduce the flow of air. The reduced air flow will cause the fan motor to move less air and therefore have a lighter load. If the filter is alowed to get too dirty, the components down the line will suffer because of insufficient air flow and the motor will have to run longer to achieve the disired temperature. So what the repairmen are saying is a more expensive filter will catch more dirt and keep the fan motor running longer. True if you let the filter get too dirty. Cheaper air filters let more dirt through the fan, motor, ductwork, etc get dust and dirt buildup. This will eventually require service to clean and remove the dirt and dust buildup. In my industrial experience, 20+ years, put in the best grade filters you can reasonably afford and change them at the recommended intervals or sooner if needed. This will keep the proper amount of air moving and help keep the ductwork, fan blades, etc cleaner. I've also found that the electrostatic filters catch a lot more dirt and dust than the non-electrostatic filters. I've used 3M Filtrete 1000 but now run either a 1500 or 1900, depending on which I can find at the store. Since I have 6 cats I want the best filter I can afford to help clean the air. That's my 2 cents worth, but it's the truth, not conjecture.

This is something that I have wanted done since the day we moved in and guess what I have been told?? That it's not needed in a new house but why all the dust??

I use a re cleanable filter based on static/magnetism, Closest I can describe it. I used it in my old system that I replaced last year. The old system was 20 years old. The filter still works perfectly, Paid about 60 bucks back then. Wash it out monthly with ammonia Then flush with water

My experience is this: my Lennox HVHC system is over 22 years old. I've replaced the blower moter once when I couldn't afford the recall and upgrade even at 1/2 price (wish I had but too late now). I've used the GM filtrets for years, and had my system maintained prof. for 19 yrs. The hvac tech used the middle of road filter but since I discoverd the 1500-1900 filtrets, I've experimented w/when I change them. Just did my 2 mo. change tonite. Used to wait for 6 months to let tech do it (yikes) and now I do it my self. with four pets and all of us wlong hair, a 4 story carpetd townhouse - the filters get very dirty w/in 2.5 months, so i may go to 1'x a month just to keep the system running for as long as I can. I know i'm on borrowed time but still - 22.5 years isn't a bad track record - most other unit owners have replace dhteir entire system due to neglecting them.

Everything mechanical is a matter of tolerance. Too little filtration makes downstream motors, blades, etc. clog and lose life. Too much filtration restricts airflow and causes less efficient work to be done by down stream components. You should check a new filter weekly in your house to see (measure/characterize) how time frame it takes till it needs replacing. Repeat this test until confident. (More data points = more confidence) Take into account other factors when deciding level of filtration: allergies, age of equipment, clean/dirty environment, season, cost, time, etc. How much can the system tolerates with the least impact to life is the question you are trying to answer. Like everything, every situation is unique and require a bit of work. Nathan Mechanical Engineer

Here is what 3M says about their Filtrete filters that I use. Ideally there would be a spec for maximum pressure drop across the filter in a system and a way to monitor it. If you use a Filtrete filter for longer than three months, it may begin to restrict airflow or cause your heating/cooling system to malfunction. It also could restrict airflow in some higher-efficiency air conditioning systems. When in doubt, change the filter more frequently.

With respect, careful who you listen to Ann, Linda & James, as you may have been misinformed. My former HVAC people once told me nearly the same thing. I ran this past my best friend, a environmental engineer, who holds a mid level government security clearance, that said essentially what this article said with respect to filters. My friend's info was also recently reconfirmed by a HVAC professional that provided a bid to replace my entire HVAC system. Two final items of note for the record: 1.) I was unable to use the aforementioned HVAC professional's bid, as it was a bit too high. 2.) The same HVAC professional was also a engineer, with a degree in mechanical engineering from Purdue.

Actually as long as you change your filter on a regular basis the pleated filters are great. And actually keep alot of debris from getting into your blower motor. Debris that can cause damage over time, and cost you more money in repairs. Keeping your air clean also keeps your system clean and prolongs it's life.

We had to replace our blower motor twice and stopped using the allergin filters to save the motor. So far we have not had a problem with the pleated filters that are about $5 apiece, so that is what we use now. An A/C service in Dallas told me to use the cheaper filters and spray the intake side lightly with End Dust. I find that to be very effective

I agree, the more expensive filter is far the best. Cheap ones will work, but still do less even when replaced frequently. Yes, HVAC may work harder and need more maintenance, but that is worth the cleaner air. I always want the best quality of everything, especially food. Cheap food costs a lot more for doctors and drugs they prescribe.

It's just more maintenance cost, it's breaking your unit. If you reduce the air flow too much you can freeze the evaporator coil which stops your house from cooling and can cause overflow water coming over the drain pan. Also it can burn out your blower motor from making it draw more amps than its designed to do.

This is an old topic - but it came up on my search - so maybe somebody else will see it too? The less air you move the less energy you are useing. Not the other way around. Less air = less work = less amps = less KW = lower energy bill. By no means am I saying let your furnance filter get dirty - I am saying it's completly wrong to think that a dirty filter is goin to somehow burn up, hurt, break, short, or any other slack jawed term you can think of your blower motor.

Your logic is wrong. The motor is not moving the air. So using a work formula on moving air is useless. The fan blades are moving the air not the motor and yes.... doing less work due to less revolutions and having to overcome a partial vacuum behind the filter. The motor is turning the fan blades. When you have a more restrictive filter the motor has to push the fan blades under a greater resistance(working harder) if you don't understand motors you should probably not be so condescending. For example please research stall current on motors or even start up current. Motors can draw 10 times normal current when they are under stall conditions. When a motor is under greater resistance the amps go up... amps determine heat generated through resistance(the reason you cant use a tiny wire on a big motor tiny wires have more resistance). So the greater resistance of the fan blades results in EMF resistance in the motor to which the motor responds by increased amperage. And the notion that a more restrictive filter lowers your electric bill is silly. I mean that just resists common sense.... but here is a formula for you. Power consumed has nothing to do with how much air is moved. Power(P=watts) is electrical pressure(V=Volts) x intensity(I-amps) P=IxE so as the resistance increases(like a stall condition or a start up needing acceleration) the more power is consumed. Lets make a fake formula 2 amps x 208 volts = 416 watts. now lets say we increase amps to 3. 3 amps x 208 volts = 624 watts. It is a fairly direct correlation. That all being said... I still use nice filters because it makes a huge difference my allergies. My face used to be puffy in the morning and I had sinus infections a lot... now I barely have either. For me the extra work on the blower motor is worth it... Although people are using scare tactics and the service men will use scare tactics as well.. The only thing it is going to hurt is slightly more electric usage and a little more wear on the blower... your evaporator is not going to freeze up as modern systems have temperature sensors to prevent that just like modern cars. Your condenser outside does freeze up to extract heat from the air when its very cold outside but that is normal as it will then go into a defrost mode. afterward.

My HVAC repairman stated the same thing that Ann did in her email IF you have an older unit and you don't have allegeries. The pleated ones make your system work too hard and can burn out the unit.

My furnace repair said that 3M Allergen filters are the worst for placing extra load on the blower motor. They really advise against "high efficiency" and "allergy" filters because of damage on the blower motor due to impeded air flow. However, if you need to use one of them for health, then they say to always change them EVERY 30 days no matter what. That way you don't have as bad a drag on the blower motor. Beyond 30 days those filters are clogged even though they don't look "dirty".

I totally disagree. My HVAC repairman said to use the cheapest filter available. The pleated style cost more and make your unit work harder and wear it out faster. They place quite a strain on the unit. Change your filter every 4 to 6 weeks and get your duct work cleaned when necessary.

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