E-series cabin air filter retrofit?

carringb · 09-12-2020, 02:54 PM

Anybody ever find some space to stuff a cabin air filter into the front HVAC? Honestly, I've never had to open mine up, but I'm hoping somebody who's done any vacuum line or heater-core work can remember if there's any space in there? I don't really feel like taking things apart outside right now, without knowing there's a chance it'll work....

At least the rear HVAC is easy to retrofit (furnace filter and painters tape).

Looking like we've stuck with the smoke for a while still...

SheepShagger · 09-12-2020, 05:29 PM

Absolutely no space around the vacuum box, my box failed and I wasn’t going to rip out all the heater core just to get to it. So after studying the repair manual diagrams for a few hours, I decided the best corse of action was to cut hole in inner fender, pull vacuum line and make my own box. I put the box behind passenger headlight. There is absolutely zero room anywhere behind or in front of the bulkhead in that area.
Probably not much help, but here are some pics.

JWA · 09-13-2020, 09:29 AM

Not sure this will be very helpful but it does show the other side of the intake box:

Without cutting into the inner structure one might be able to fabricate something to fit over the inlet opening just under the windshield cowling? It wouldn't be pretty but might work.

Are you thinking a pleated paper filter or something charcoal based?

BTW my best wishes for y'all living on the west coast---that can't be easy these days.

carringb · 09-13-2020, 09:37 AM

Thanks both of you. Those literal cutaway views are very insightful!

Ideally I was hoping to find enough space a HEPA sheet style cabin filter. No charcoal. Just something to grab the harmful small particulates.

That plenum under the hood does look big enough. Just not sure if it’s worth the trouble getting to it. Backup plan is just running Max A/c for front recirc and taping a MERV-13 furnace filter over the rear HVAC return. I’m using a merv-13 on a box fan and another in the furnace, the it’s done wonders for air quality in the house.

Oly11 · 09-13-2020, 10:35 AM

I was driving through the gorge on Friday and was wishing for some extra filtration as well but wasn't sure what was possible as I had never had that thought before all these fires. The filter over the rear return is definitely an easy option and one I will be trying this week.

arctictraveller · 09-13-2020, 12:32 PM

I've wanted to install a filter that would pressurize the inside with filtered air to keep the dust out. I did cut a furnace filter to fit my Maxair fan housing and then ran the fan on high, blowing air in. It probably worked a bit since the filter got pretty clogged at the end of the trip, but it reduced the air flow while camping and was a pain to install and remove. Next I tried using a 7.3 air filter installed in a box with a 12v muffin fan, with the box fit over one of the small sliding windows on the side. Once again, air flow was pretty minimal and I never really gave it a serious try. The new plan is to find a squirrel cage fan of some sort, similar to those used in a rear air set up. With the fan in a cabinet and a flexible duct attached to an inlet placed in the same sliding window may work. All this is to reduce the amount of dust inside, but would probably work for smoke too. Up North of you is really bad too, I haven't been outside in a few days, but fortunately we have an electrostatic filter installed in the forced air heater / AC ducting, so running the system really helps. I'd be interested if you come up with something, even a temporary solution would be good. Best of luck................

JWA · 09-13-2020, 01:25 PM

Quote:

Originally Posted by carringb

That plenum under the hood does look big enough. Just not sure if it’s worth the trouble getting to it. Backup plan is just running Max A/c for front recirc and taping a MERV-13 furnace filter over the rear HVAC return. I’m using a merv-13 on a box fan and another in the furnace, the it’s done wonders for air quality in the house.

I'm sincerely hoping the air quality situation you're facing is temporary so given that you could remove the cowling (6-7 screws at most one side) and install your filter media in the inlet area. It would be a bit unsightly to leave the cowling off BUT you'll have a bit better degree of filtration to the limits of your filter media.

I like the idea of a pressurized cabin interior but that would be a bit complicated to do since you're also pulling outside air through the heater or A/C core(s)

Make sure your door seals are pliable enough to exclude outside particle-laden air----I'd use a 3M 08877 Wet Type silicone lubricant to retain their pliability. FWIW that same material works wonders in climates where below freezing temps can have the seals stick to the door shells and pull them loose.

HTH and best of luck getting your filter system in place.

boywonder · 09-13-2020, 04:06 PM

FWIW.....I used to design surgical smoke evacuators. These are basically vacuum cleaners with HEPA filtration and charcoal/carbon for VOCs. They are used in surgical procedures when there is lots of cutting and cauterization using electrocautery (bovie) knives since there is lots of biohazardous smoke generated.

To get HEPA (High Efficiency Particulate Air) performance, which is 99.97% efficient at .3 microns (particles that are larger and smaller are easier to filter out) HEPA filter media has a face velocity specification. The face velocity calculation is simple; divide the air flow rate by the filter media area. If you stay below the specified face velocity you get HEPA performance....exceed it and you no longer get 99.97% efficiency.

99.97% means that 3 particles per 10,000 manage to get through the filter (.3 micron size).

....and since it's COVID season..N95 filters are 95% efficient, so 5 particles per 100 get through those (.3 micron size). N95 is a NIOSH specification.

ndubes · 09-17-2020, 10:39 AM

I think a lot of us have been thinking about this same thing

I went down some very complicated rabbit holes like this, but ended up deciding perhaps the best and easiest solution was just to buy an air purifier and keep it plugged in. There are a lot of options on Amazon and a lot of them just plug into USB (we have 5 or 6 USB ports installed in our van) so they shouldn't take a lot of power. Very easy to clean, very inexpensive and for the size of your van you shouldn't need a very big one either. I bought both of these, I'm hoping the smaller one is sufficient. They haven't arrived yet but have used similar ones in our home with great results so I am optimistic about this as a solution.

https://www.amazon.com/gp/product/B0...KIKX0DER&psc=1

https://www.amazon.com/KOIOS-Upgrade..._t2_B07RGP9PNS

carringb · 09-18-2020, 06:55 AM

This is all I had time to hack together for now, but the good news is, it works great! Just have to keep the front on MAX.

Had to settle for a MERV-11 filter. MERV-13 is what I'm using in the house.

I think there might be enough space make something in the future, most likely 3D printed.