Healthy Climate X6675 HCF20-16 MERV16 Carbon Clean Replacement Air Filter 25"x20"x5" - Improves Indoor Air Quality for Homes & Offices

This will be a pretty long review for a furnace filter but, it seems there is a lot of confusion around them and this one in particular. I'll try to clarify. TL;DR - if you check independent testing out there this is probably the best filter you can buy for your furnace and it does so with a very modest pressure drop (more on that later).SIZESUnfortunately, the HVAC industry loves to confuse people about this. By my count, there are no less than FOUR different filter sizes out there for filters labeled 20 x 25 x 5. So, what size is this filter REALLY? It's 19-3/4 x 24-3/4 x 4-3/8 (even one of Lennox's websites has a typo on this). In the industry, they tend to round up if the size is ANY fraction above the whole number.This is a LENNOX filter, "Healthy Climate" is Lennox's line of HVAC parts and accessories. It's specifically designed to fit Lennox's HCC20-28 air cleaner box. This is the ONLY box they certify it to fit in. Now, with that said, other manufacturers (Honeywell, Carrier, and others) use this same size as well, and they're listed on the filter (I'm not listing them here, look at the photo).So, check to see that you have an air cleaner box this will work with. Even if your furnace isn't a Lennox, your installer might have used a Lennox air cleaner box (particularly if Lennox is the main brand they sell). Check your air cleaner box or OEM filter part number against the list on the filter and see.THEY'RE MEANT TO FIT TIGHTIf your filter doesn't have a tight fit, then air can get around the filter, and it's not doing its job, so the fit will be tight. I've found that if I put the filter in with a slight downward tilt (as it needs to get around a bracket for the air cleaner cover), it will then slide into the box fine. I have a Lennox furnace with the HCC20-28 air cleaner box; the fit is tight, and it's SUPPOSED to be. Thankfully Lennox puts holes at the end of the filter to help you remove them (I switched to using the OEM filters almost for this fact alone).HIGH MERV AND STATIC PRESSUREThere is some truth to what floats around on this and some myth. Yes, a higher MERV filter MIGHT create a significant drop in static pressure than a lower MERV. This drop makes the system's fan work harder to push the air. However, much more goes into what creates a drop in static pressure than the MERV rating, most of it has to do with the filter's design.If your system is older or you are changing from a thinner filter to this one, you have cause to be concerned about this. If your furnace already has a 5" filter to begin with your system probably shouldn't have any problem using this MERV 16 filter versus the MERV 11 base-model filter this part is an upgrade to.All said this is a filter made by Lennox, I don't think they would make it and list it as an upgrade to one of their other filters (Cat No. X6673) if their systems weren't able to handle it.NO FAN, NO FILTRATIONTo get the benefits of using a filter like this, your fan needs to be running. If your fan isn't running much, I probably wouldn't waste my money on this filter and just go with the MERV 11 (X6673). My furnace has a variable-speed fan that is designed to run continuously, so I never shut it off. It's designed to do that and uses very little power. Most modern furnaces are designed this way. By continuously running the fan it's more comfortable, and the air is continuously being filtered.Another benefit of running the fan continuously is when you are most affected by a static pressure drop and when the fan of your system has the most stress on it is when it starts. By continuously running your fan, if that's something it was designed to do, you're virtually eliminating that stress on the fan.FILTER LIFEPer Lennox, this filter is rated to last UP TO a year. Your experience will vary on how long this will last for you. Since I have pets and continuously run my fan, I go with 6 months for this filter. That's still a ton longer than the cheap (and even not-so-cheap) filters.If you're frugal, check the filter at intervals after 6 months and see how it looks. This design has SO MANY pleats it's built to be able to go a long time. Check the pleats and see if you have any clean or nearly clean surfaces left. Then decide for yourself how long you want to go before changing it.ACTIVATED CARBON MYTHSThere seems to be some myth here that activated carbon needs to be hermetically sealed or something in order to work right. This isn't the case. Activated carbon is more porous so most manufacturers of activated carbon filters will wrap them to prevent exposure to excessive airflow. Folks, we're talking bout something DESIGNED TO HANDLE A LOT OF AIRFLOW here. If the filter wasn't completely sealed that doesn't mean it was ruined, there's no way it saw a lot of airflow sitting in a box. I've got a couple of air purifiers in my house and do their carbon filters come in a bag? Yes. Is that bag airtight? Nope, not a single one I've seen, OEM filter or otherwise.I will say that these filters come bagged from the factory (which is nice for disposing of your old filter). If you get a filter without a bag, there's a chance it was returned by someone who got (or thought they got) the wrong size. Whether you decide to return that I leave it to you but it doesn't necessarily mean the filter was ruined.IN SUMMARYI was running a couple of different brands for a while and decided to go with the OEM brand for my furnace as I believe the OEM's have either dropped their prices some or the prices of aftermarket filters have been going up. I wasn't seeing a huge price difference, and, if you want a carbon layer your choices are going to be few.This filter has a ton of pleats, more than I've seen in any other filter short of a HEPA. The independent testing that's out there verifies this is one of the very best filters you can buy (there's only one I've seen rated better, and that's because of its housing). If I was replacing a filter more regularly, I'd be more concerned about the price difference versus an aftermarket filter than I am. I think the OEM filter is built better and designed for longer life so I think the higher price is offset by durability and peace of mind.