I have been cleaning, repairing and installing only residential furnaces and a/cs exclusively since 2001.
I get the same questions and I see the same problems year after year, visit after visit even though I always explain and show my clients what, how to and why to do it.
I will write it here for everybody to see and I might revise it from time to time as I too am always learning, unlike some other guys in the trade I don’t know everything.
But one thing I learned well is this:if you want to greatly reduce furnace and a/c problems and achieve the best possible comfort and efficiency keep your furnace and a/c clean and dry !!
Let me explain further. Always use a decent filter and by that I mean a filter of merv 8 to 11 and change it often enough so it’s never plugged up with dirt and dust. Which usually is 2-3 times a year if your fan is set to automatic so it’s not running 24 hours a day (see:should I be running my fan all the time section).
If your fan is running all the time you should be replacing that filter every 2-3 months. These frequencies refer to a one inch disposable filter. If you have a 4 or 5 inch paper filter then you should be replacing it every year on auto mode or every 6-8 months if the fan is running 24/7.
These frequencies will heavily depend on the conditions inside your home and these are:traffic,number of occupants, smoking, pets, home renovations and greatly on how clean your home is to begin with.
Don’t ever think-despite what you might have been led to believe- that an expensive filter -and I am talking about $20-30 each for a one inch filter-will ever make the air in a dirty home clean or it will protect you from allergies due to household dirt and dust. Don’t waste your money. If you want to breathe clean air in your home keep it clean and air it out whenever possible. That restores oxygen levels indoors and its healthy.
If you have a washable filter make sure it’s a good one and not one of those blue-green mesh filters that have holes you can stick a finger through. You can get decent washable filters for 30-60 dollars at you know where, but I prefer disposables. For $15-20 a year ($5 a filter) you get very good protection without restricting airflow and nothing to wash. I’ve found that the vast majority of people don’t ever wash these filters properly or often enough. Very dense (very expensive) filters will restrict air flow even when new and even more so as they get dirtier. That can cause big problems sometimes and it will always make the furnace or the a/c work harder. If you feel you must use such filters you must change them even more often.
If you have one of those electronic air cleaners with the cells you have to wash, just throw it away. Despite lab tests that say it kills all the germs and viruses and allergens and stops all the dust , I am sure that by now you know that it’s not true. Unless you wash that thing properly and at least weekly it will never perform as designed.
Take it out and use a disposable paper filter Merv 8 or 11. You’ll be happy you did and you’ll save yourself the trouble of washing it . Also you’ll keep your furnace cleaner and it will thank you for it. Keep the two small prefilter screens that come with it, place them on the side that’s close to the furnace and in front of them place one of those paper filters. You don’t have to attach it with nothing, it will stay there by the fan moving air through it. Replace as needed.
People always ask me which way to insert the filter in the filter rack adjacent to the furnace. All filters have a directional arrow on their cardboard frame. That arrow must point towards the furnace. Simple. Also what I like to do is to write with a marker the date I put the filter in on the side of the filter that is exposed to the outside of the filter rack or visible to the outside. That way by just passing by I can see easily when I put it in and if I should be replacing it. EASY ! Back to maintenance tips now.