5 ms·

I've had HVAC techs tell me not to use those thick filters unless your system is designed for it. They make the fan work harder to pull less air. This reduces h

I've had HVAC techs tell me not to use those thick filters unless your system is designed for it. They make the fan work harder to pull less air. This reduces how much air it can move.

SigmundA 4y ago
A good system like an AprilAire [1] will have a 4" thick filter vs the standard 1" thick filters. This allows much more filter area than a standard filter allowing proper airflow even with a finer more restrictive filter medium. You can't just swap filters, the 4" thick one usually go in right before HVAC air handler intake rather than at returns. I have had an AprilAire installed for over 10 years in my HVAC when it was replaced last time, recommended by HVAC installer, its has worked very well and I do have my blower fan cycle constantly regardless of need for heat/cool to turn over and filter air. 1. https://www.aprilaire.com/whole-house-products/air-purifiers/air-filter-buying-guide https://www.aprilaire.com/whole-house-products/air-purifiers...
bombcar 4y ago
You can have them do a test and adjust the system depending on the filter that's installed to make sure it's moving enough air (though that is mainly important when heating to prevent the heating element from overheating).
- dr_orpheus 4y ago
  It is also important in the cooling cycle for two reasons. 1. If there is not enough air moving over the air-conditioner coils there is the possibility that they will ice over. This has a cascading effect where there is less transfer through the coils and more ice builds up until the whole thing is a block of ice. This most often happens though when people buy condensers that are too big for their system (the thinking being the bigger the better the more cooling, but it is a balance within some tolerance) but can also be done on the other side by reducing airflow too much. 2. Less airflow can also mean too much condensation in the air which can end up sitting in the ductwork and causing it to rust out. This happened to my parents when they installed extra filters in their HVAC system. I guess this is similar cause as #1, just different potential effects.
itsoktocry 4y ago
>I've had HVAC techs tell me not to use those thick filters unless your system is designed for it. Yeah, it will also shorten the lifespan of the motor since it has to work harder. But is the cleaner air trade-off worth it? I think so.
- larrywright 4y ago
  It’s a trade off though, because good filters will keep dust out of the HVAC systems innards, which according to the techs I’ve talked to makes a difference in longevity.
- malfist 4y ago
  I've always heard this, but I don't know that that's true. The thing that dies first on an HVAC system isn't the motor, it lasts a long damn time, it's the capacitor, or contactor or some other fault not really related to the motor work load. Plus, your "motor" isn't an engine, it's not variable speed, it only has one "hardness" that it works at. It might push less air with the thicker filter, but it's not going to ramp up and consume more wattage or anything like that.
  - foobarian 4y ago
    >Plus, your "motor" isn't an engine, it's not variable speed, it only has one "hardness" that it works at. This is incorrect - electric motors draw more current when under load. I would suggest researching this or playing with some toy electric motors run from a battery through a current meter.
    - creaturemachine 4y ago
      That's true, but it's not so simple anymore. Furnace blowers are all electrically commutated brushless DC motors now, and will ramp to keep a constant torque.
    - malfist 4y ago
      I have a degree in electrical engineering, thank you for telling me to do my research, I spent four years doing that. Sure, some motors have characteristics that can be tweaked to run at different work loads either with PWM, or allowing them to pull more amps to drive higher loads. Hell, you can even overvolt them and make them actually work harder. That's not how HVACs work though. Have you ever opened one up and did a repair? The circuitry is dead simple, there's no current limiting setup or PWM to control how much the motor is pulling or spinning, there's no CFM measuring device to give the motor more volts or a higher amp limit. The motor is simply pushing air. Air isn't something like a solid load where a motor might lift something or move a lever or gear, it's fluid. The motor is going to run at max and be done.
deleted 4y ago
[deleted]

I've had HVAC techs tell me not to use those thick filters unless your system is designed for it. They make the fan work harder to pull less air. This reduces how much air it can move.

SigmundA 4y ago

A good system like an AprilAire [1] will have a 4" thick filter vs the standard 1" thick filters. This allows much more filter area than a standard filter allowing proper airflow even with a finer more restrictive filter medium. You can't just swap filters, the 4" thick one usually go in right before HVAC air handler intake rather than at returns. I have had an AprilAire installed for over 10 years in my HVAC when it was replaced last time, recommended by HVAC installer, its has worked very well and I do have my blower fan cycle constantly regardless of need for heat/cool to turn over and filter air. 1. https://www.aprilaire.com/whole-house-products/air-purifiers/air-filter-buying-guide https://www.aprilaire.com/whole-house-products/air-purifiers...

bombcar 4y ago

You can have them do a test and adjust the system depending on the filter that's installed to make sure it's moving enough air (though that is mainly important when heating to prevent the heating element from overheating).

dr_orpheus 4y ago
It is also important in the cooling cycle for two reasons. 1. If there is not enough air moving over the air-conditioner coils there is the possibility that they will ice over. This has a cascading effect where there is less transfer through the coils and more ice builds up until the whole thing is a block of ice. This most often happens though when people buy condensers that are too big for their system (the thinking being the bigger the better the more cooling, but it is a balance within some tolerance) but can also be done on the other side by reducing airflow too much. 2. Less airflow can also mean too much condensation in the air which can end up sitting in the ductwork and causing it to rust out. This happened to my parents when they installed extra filters in their HVAC system. I guess this is similar cause as #1, just different potential effects.

itsoktocry 4y ago

>I've had HVAC techs tell me not to use those thick filters unless your system is designed for it. Yeah, it will also shorten the lifespan of the motor since it has to work harder. But is the cleaner air trade-off worth it? I think so.

larrywright 4y ago
It’s a trade off though, because good filters will keep dust out of the HVAC systems innards, which according to the techs I’ve talked to makes a difference in longevity.
malfist 4y ago
I've always heard this, but I don't know that that's true. The thing that dies first on an HVAC system isn't the motor, it lasts a long damn time, it's the capacitor, or contactor or some other fault not really related to the motor work load. Plus, your "motor" isn't an engine, it's not variable speed, it only has one "hardness" that it works at. It might push less air with the thicker filter, but it's not going to ramp up and consume more wattage or anything like that.
- foobarian 4y ago
  >Plus, your "motor" isn't an engine, it's not variable speed, it only has one "hardness" that it works at. This is incorrect - electric motors draw more current when under load. I would suggest researching this or playing with some toy electric motors run from a battery through a current meter.
  - creaturemachine 4y ago
    That's true, but it's not so simple anymore. Furnace blowers are all electrically commutated brushless DC motors now, and will ramp to keep a constant torque.
  - malfist 4y ago
    I have a degree in electrical engineering, thank you for telling me to do my research, I spent four years doing that. Sure, some motors have characteristics that can be tweaked to run at different work loads either with PWM, or allowing them to pull more amps to drive higher loads. Hell, you can even overvolt them and make them actually work harder. That's not how HVACs work though. Have you ever opened one up and did a repair? The circuitry is dead simple, there's no current limiting setup or PWM to control how much the motor is pulling or spinning, there's no CFM measuring device to give the motor more volts or a higher amp limit. The motor is simply pushing air. Air isn't something like a solid load where a motor might lift something or move a lever or gear, it's fluid. The motor is going to run at max and be done.

deleted 4y ago

[deleted]