DIY combo air cleaner/humidifier

[Glenstr]

TL;DR

built a Corsi-Rosenthal box, can I use it as humidifier as well?

Last winter I built a corsi-rosenthal box filter to help clean air in the house, I built it 5 sides with 20"x20" merv 13 rated filters. I was impressed with how well it worked, and am implementing two of them this winter. We have 2 dogs & 2 cats so pet dander as well as dust can build up a lot.

Because we deal with very dry air in the winter here, I also run an evaporative humidifier 24-7 during the cold winter months. We probably need another one as the house is large and it raises the humidity in one area only.

So I am thinking of building one with just 4 sides, and setting it over a vessel of water so the incoming air is pulled past the water, the thought being it may help with the humidity issue, even if it's minimally. To make it more efficient, I was thinking of suspending a towel from a rod of sorts that would rest in the water vessel, so that water wicked up into it and increase the water surface area the incoming air passed over.

The evaporative humidifier I have has a circular foam filter of sorts that sits in the water filled bottom, and a fan pulls air through it as it wicks the water from the tray. This got me to thinking putting a similar circular filter in the vessel of water (a large stainless bowl) might be a better idea, and if I really wanted to improve it implement some sort funnel from the box fan down to the filter, much like the commercial unit does.

I was hoping some of the more knowledgeable engineering types here might chime in on whether or not the idea of incorporating a humidifier into it is plausible (or not), and if so, what would be the most efficient way to do this without getting too complex.

 

[BillTre]

Here are some thoughts.
Evaporating from a surface is not going to add a lot I think.
At least the surface should be aerated or agitated to increase evaporation. Heated water would help (aquarium heater?).
An aeration device that makes lots of very small bubbles in an air flow going through a body of water would humidify the air well.
Spraying a mist into the air would be very effective, but might be too messy.
Getting water on the filters that the air is going through would probably be very effective.
But stuff would probably grow in the filters, which would have to be cleaned or replaced.

You might want to figure out how much water you should be targeting to put into your air to achieve your goals.
After some math, you should have an idea of how many gallons of water you want your device to put into the air. You could measure this and use it to determine what process might work best for you.
You could also do before and after humidity comparisons to determine the effectiveness of whatever you are doing.

 

[Glenstr]

I may buy a foam filter like my current evaporative humidifier uses, only larger and set it in the bowl of water and see if/how much that accelerates the evaporation. My current humidifier goes through about 1.5 to 2 gallons in a 24 hour period to keep our bedroom above 40%, so I could compare water consumption between the two.

If it doesn't seem to help I was thinking I could build a giant funnel of sorts out of chloroplast or something that would rest inside the round foam filter on the bottom and have the same circumference as the fan blade in the box fan at the top.

Running an aerator seems like a good idea too, but then I'd be sitting the box on a cord & creating a gap that air would get pulled through bypassing the furnace filters, which I also don't think should get wet, to your other point.

I have some cheap hygrometers around too so I can monitor differences (as soon as I remember where I put them)

 

[Borek]

I strongly advise against spraying a mist, unless you use DI water. It produces very fine, white dust that can be irritating to lungs (it is for me, but not for my wife) and is visible on darker surfaces (which is irritating for my wife, much less for me).

 

[Dullard]

Not exactly to your question, but:
Another way to increase the humidity in your house is to reduce the rate of water loss. Human/pet respiration is a constant source of moisture (in addition to any intentional 'humidifiers'). The primary culprits for water loss are:

Air leaks
Cold-surface condensation (windows, etc.)

If you address these, your 'make-up' water requirement will be reduced. You might also find that your power consumption is reduced - you'll avoid the energy cost of heating the 'new' air and the energy cost of evaporating the required water.

'Fog Nozzles' work very well, but definitely do have the issues described by Borek (water quality dependent). They can also turn into 'drip nozzles' after some mineral accumulation at the nozzle outlet.

 

[russ_watters]

Getting water on the filters that the air is going through would probably be very effective.
But stuff would probably grow in the filters, which would have to be cleaned or replaced.

There's also a good chance this could damage filters, as most are framed with cardboard.

 

[russ_watters]

I strongly advise against spraying a mist, unless you use DI water. It produces very fine, white dust that can be irritating to lungs (it is for me, but not for my wife) and is visible on darker surfaces (which is irritating for my wife, much less for me).

That is true of ultrasonic humidifiers, which atomize the air, but it may not be an issue with a micro-irrigation spray/fog nozzle. I'm envisioning spraying the mist downwards onto a pan, with the air flowing in/up from the sides. The water droplets would be too big to evaporate completely, keeping the dissolved minerals dissolved. The system would require periodic flushing/cleaning (which is typical in humidifiers anyway).

 

[Borek]

That is true of ultrasonic humidifiers, which atomize the air, but it may not be an issue with a micro-irrigation spray/fog nozzle.

When I was a kid we had some kind of an A/C device that produced a "fog" (definitely not an ultrasound device, something like an air spray gun producing a constant stream of air with suspended droplets, it cooled the air by evaporation). As far as I remember (heck, it was almost 50 years ago) it was even worse than the ultrasonic humidifiers when it comes to the white residue.

At the time my lungs and throat didn't bother.

 

[russ_watters]

When I was a kid we had some kind of an A/C device that produced a "fog" (definitely not an ultrasound device, something like an air spray gun producing a constant stream of air with suspended droplets, it cooled the air by evaporation). As far as I remember (heck, it was almost 50 years ago) it was even worse than the ultrasonic humidifiers when it comes to the white residue.

It may depend on what exactly you are describing. Systems like that are used outside, without drainage and producing small particle sizes. They absolutely will leave residue because even if the dropplets don't evaporate before they hit the ground, they'll evaporate on the ground. The key is, to get residue the dropplets have to evaporate completely otherwise the remaining water will just carry-away the dissolved minerals.

 

[russ_watters]

Thinking more about @BillTre's spraying water on the filters idea; There is a typical residential humidification method that uses panels with water spilling over them, and there used to be ones that rolled flexible substrates over a drum. You could replace one of the filters in this box with such a panel, that's designed to be wet. These as you can imagine get nasty after a lot of use and have to be cleaned/replaced (they grow mold and get mineral deposits on them):
https://www.lowes.com/pd/BestAir-Re...rFgdxeqkwnQ_rDou67IaAoRzEALw_wcB&gclsrc=aw.ds

https://www.discountfilters.com/hum...0FJB1L1PWxZzKGMzjdWHHcESftF9KJAEaAhFqEALw_wcB

The second one might not even need a circulator pump, I think it just works by wicking.

 

[BillTre]

Thinking more about @BillTre's spraying water on the filters idea; There is a typical residential humidification method that uses panels with water spilling over them, and there used to be ones that rolled flexible substrates over a drum. You could replace one of the filters in this box with such a panel, that's designed to be wet. These as you can imagine get nasty after a lot of use and have to be cleaned/replaced (they grow mold and get mineral deposits on them):

I was thinking of swamp coolers when i wrote this:

Evaporative cooling is also evaporative humidifying.

I have seen these in fish farm greenhouses. They use a plastic mesh or matting of some kind (common on fish farms) with water running over them and a big fan blowing air through it. They can be pretty primitive and still work.

 

[Lnewqban]

Copied from
https://www.cdc.gov/healthywater/drinking/preventing-waterborne-germs-at-home.html

“Germs can live in humidifiers unless you empty them of all water daily, clean them properly on a regular basis, and allow them to air dry after cleaning. These germs can spread through the mist created by the humidifier when you turn it on.”

Please, see:
https://en.m.wikipedia.org/wiki/Legionnaires'_disease#Reservoirs

 

[Dullard]

I never walk immediately downwind of a cooling tower.

 

[Glenstr]

I've reverted back to just having the Corsi-Rosenthal box server as an air cleaner. My 4 sided Corsi-Rosenthal box with a vessel of water in it & a foam element (from a furnace humidifier) standing in it did not evaporate water at a rate high enough, at least not compared to my stand alone evaporative humidifier.

I picked up 5 Merv-14 2500MPR filters and turned it back into an air cleaner only - which by the way, works very well should anyone be looking at air cleaners and don't want to shell out the $$ for a hepa filter.