Installing MERV 16 filters in HVAC systems vs. stand-alone air purifiers

[DonaldsRump]

Hi all:

I need some advise as to which is the better way to go to clean the air in our house: several standalone air-purifiers vs. getting an upgrade to our furnace that will allow a 5 inch MERV 16 filter that supposedly takes out most pollutants etc.

We have a 2 story house with 2 furnaces (no A/C). We live in the Bay Area, so most of the time, we don't need a/c.

However, with the fires from the last couple of weeks and the high heat, we couldn't open the windows. We had a few fans that made things slightly bearable. I then remembered we could use the fans on the furnace to also help and that also helped alot.

Anyways, we want to get our HVAC ducts cleaned, and the company, which is highly rated, also offers a filter upgrade, where you can replace the normal flimsy air filter with a 5 inch monster filter that is MERV 16.

Has anyone done this? What are the pros and cons of doing a filter change like this? Since we have forest fire smoke issues, I am concerned about the air we're breathing. From what I can see, good air purifiers are quite expensive, and we would have to buy several. Since we can use the fans on the furnace to circulate air, I'm wondering if the filter upgrade is the better way to go (keeping in mind we would have to do this twice since we have 2 furnaces).

Any thoughts would be MOST WELCOME!

Thank you!

[Phoenix61]

1. It depends on how they do it. The blower in your

furnace may not be designed to push or pull air through a five inch thick anything.

[DonaldsRump]

2. Thanks for that

I was just reading some articles that made exactly the same point.

Our furnaces are getting older, so I doubt they are able to deal with this. We are having our annual furnace maintenance coming up in a few weeks and I wanted to get some estimates for new units if/when need to replace them. I will make sure that we factor this point in for any new system that we get.

[Chasdev]

3. Whole house filters

We had to replace our HVAV system 8 months ago and I insisted on a whole house filter system at the same time.
The installer replaced the entire evap box with one that takes the large filters for $500 extra.
As an allergy sufferer, I promise you it was worth every penny.
The difference is ambient household dust is amazing, our Swifter is used much less.

[DonaldsRump]

5. That sounds about right

The more I think about it, it makes sense to filter the air through the HVAC system. But, like you, I think we need to wait to do this when we replace our units (which, hopefully, is not very soon!)

I guess we'll go with stand-alone purifiers for our bedrooms for now and then carefully design our system when it comes time. We don't have A/C now, and I'm thinking we need to go that way as it is indeed getting hotter. When we had the double whammy of the forest fire smoke AND the near 100 degree temps, and not being able to open windows, it wasn't very comfortable. I don't want to go through that again, but I think this is just the reality of life here. Most days in the summer, we don't even need fans. So the A/C is more for the smoke than anything else.

[FBaggins]

4. If the system can handle it... they're much more convenient.

Only need to be changed once a year and, in our case, are much easier to get to (ymmv). I was constantly forgetting the old one.

[Takket]

6. a larger filter will strain your supply fan

you will not get as much airflow in your system which will decrease your efficiency. It will cost you more to run the system.

You are probably better off buying a stand-alone room filter. Depending on how large your home is you may need more than one. The large honeywell ones are like $200 i think.

[DonaldsRump]

7. Thanks to all who replied

Your advice was well-taken.

I had the duct cleaning folks come in yesterday, and it was AMAZING what they did. Cleaned all the ducts and patched/replace the ones that had problems. That was what I expected.

What I didn't expect was they removed blowers from both furnaces, completely cleaned them and completely cleaned the furnace itself, the returns, and the vents. Our furnaces now look like they are straight out of the box. I am sure the air we are now breathing is much cleaner.

In that regard, we replaced the cheap filters I had installed with MERV 11 ones that I got from Amazon. They are still one one inch think (not the massive 5 inch thick MERV 16 in my OP), and they should be pretty fine. It's very hot in the Bay Area now (nearing triple digits) and very poor air quality because of the smoke from the fires. However, although we have the windows closed, we are now using the fans from the furnaces without the heat to cool the house down along with a few stand-alone fans. It's working fine. I only realized a few months ago that you could use the furnace fans without the heat to cool the house down. I also checked with our main HVAC company, and they say it's perfectly fine to let the blowers/fans run constantly, which we will do for the next several days with the excessive heat warning and the smoke. Apparently, the greatest damage to the blowers comes when they are turning on and off.

Also, buy your air filters on-line, not at the store. You'll get a much cheaper per unit price and a better selection. I'm going to use this and see how it goes now.