Considering a Whole-Home Air Filter, but Need More Info

[AndrewSAshby]

Our son recently started having some pretty serious breathing issues. After testing, we traced at least part of the problem to an allergic reaction to dust mites that I can describe only as off the charts. As a result, we bought a portable air filter for his room (Blueair Classic 203) and replaced the carpet in his room with hardwood (as the doctor recommended).

We are also considering a whole-home air filter but have two main questions that I can’t seem to find great information about:

1. Will it meaningfully help with our problem, or at least enough to justify the cost?

2. If so, what product should we get (or strongly consider)?

3. Should I be looking at a different solution?

4. Where can I get solid information about the various options, and the effectiveness of those options?

As to the third question, internet searches seem to turn up a smaller than I expected amount of information, and that information seems to be point in all sorts of different directions. I noticed some posts on here that were somewhat helpful, so I thought I would try posting here with you helpful folks. This group seems to have a tremendous amount of information and I am eager to learn, so any help would be greatly appreciated!

[teddy bear]

What part of God's green earth do you live in? Dust mites need +58%RH for several months of the year to grow to the point of producing significant allergens. They grow where ever skin scales accumulate. So humidity and skin scales assures their growth.
I used to grow them as part of learning how to control/eliminate the allergy problem.
Air filtering is the least effective method because the fecal material from the mite gets to the sensitive person before getting to the a/c filter.
The most effective method of control is keep the %RH <50% in the living space. Mites get the moisture they need by producing a salt on their skin thaT absorbs moisture from the air when the %RH is +58%RH. Green grass climates provide more than enough moisture for them to thrive.
During the dry months of the year, the mites survive by clumping deep in the nap of cloth surfaces. Bedding, carpets, and cloth covered chairs are common places that they can be collected. A clump of dormant mites can survive 6 months without any moisture. The adults give up their moisture to provide moisture for the eggs and undeveloped adults to make it through the dry times of the year.
Keeping the home <50%RH prevents mites from reproducing after being brought into your living area on your clothes from contaminated spaces, everywhere in most green grass climates.
I participated in dust mite control project that involved 75 homes in the Dayton, OH area with Dr. Larry Arlian from Wright State Ohio U. We eliminated the mites in all of the home by maintain <50%RH in the home by adding a whole house dehumidifier to properly functioning a/c.

https://www.jacionline.org/article/S...153-X/abstract

An additional benefit is the homes are more comfortable when the indoor %RH is <50%RH. Another consideration is make sure you are a fresh air change in 4-5 hours to assure purging of indoor pollutants and renewing of oxygen.
Again what climate are you located in?
Keep us posted.
Regards Teddy Bear

[AndrewSAshby]

We live in Atlanta, GA where the humidity is consistently very high.

[RoBoTeq]

Teddy Bear's information on humidity control is something to be greatly considered when it comes to dust mites. Irritants must become airborne in order for air filters to be effective, and most dust mite issues are not handled well by filtration, at least not by filtration alone.

May I assume you are referring to an existing HVAC system for putting a whole house air filtration in? If so, there is already one in the system. The purpose of the filter in an HVAC system is to protect the HVAC equipment, not to sanitize the air. Too restrictive of air filters cause a lot more issues than they resolve.

If you want to utilize your HVAC system as a whole house filtration system for health purposes, your best bet is to use a well sealed, low restriction air filter for the HVAC equipment and have a HEPA bypass filter system installed to the return air ducting of your HVAC system. This way, the HVAC system will be protected without having an increase in static pressure while 20-25 percent of the air in the system will be run through a very effective filter system, again without adversely affecting the HVAC system. With the HVAC blower running all of the time, the air that makes it's way through the HEPA filtration system will be cleaned up quite well and continue to be so.

There are many factors to consider here. Constant air flow will hinder dehumidification and unless your system has a variable Speed blower, the constant air flow can be offensive because of the sound and/or drafts. A variable speed blower can be reduced to about a third of the normal blower volume, reducing both sound and dehumidification issues.

No matter what, you should have been instructed already to do a lot of vacuuming of everything in your house that could breed dust mites.

[RoBoTeq]

Well, I am an HVAC professional with over 40 years experience, and I have no clue as to what you are attempting to say or how it relates to this conversation. I'm thinking you are selling something?

Go ahead and make an effective comparison between traditional AC and HVAC ac system.
The biggest thing of switching to a smart energy-efficient system is lower energy bills, which is a lifetime benefit for you. These energy-efficient systems can cut your bill by at least 20%, and also cool and heat your home more effectively than an ordinary system. moreover good and latest technology mini split ensures controlling humidity in the air as well.
Now if you are confused regarding picking the company you might go for a mydashcoolairdotcom
convert it in website style and i think u would like the products.

[hvacker]

A hvac system won't clean your house. In fact it can be surprising how little an effect a furnace filter has on the whole house. It's because the air flow to the return takes place entirely just a few feet from the return grills.
It was once assumed that the entire space air was directed to the return. Drawings showing arrows large and small indicating air flow to the return. Modern instruments show this isn't the case. A point being you can blow a match out but you can't suck it out.

[RoBoTeq]

Anything that remains airborn will make it's way to the HVAC systems filter. Blow out a match at the furthest point from single central return and in a few minutes you will be able to smell that match at the opposite furthest area from the return after the smoke smell travels through the blower filter.

Most airborn particulate is heavier than air and so does wind up on the floor or furniture. Vacuuming often with the HVAC blower on is the best way to keep more particulate from being kicked back up into the air stream.

A hvac system won't clean your house. In fact it can be surprising how little an effect a furnace filter has on the whole house. It's because the air flow to the return takes place entirely just a few feet from the return grills.
It was once assumed that the entire space air was directed to the return. Drawings showing arrows large and small indicating air flow to the return. Modern instruments show this isn't the case. A point being you can blow a match out but you can't suck it out.

[hvacker]

Anything that remains airborn will make it's way to the HVAC systems filter. Blow out a match at the furthest point from single central return and in a few minutes you will be able to smell that match at the opposite furthest area from the return after the smoke smell travels through the blower filter.

Most airborn particulate is heavier than air and so does wind up on the floor or furniture. Vacuuming often with the HVAC blower on is the best way to keep more particulate from being kicked back up into the air stream.

Not according to modern studies. It's really very interesting. The studies are on the net. I would give a link but will need to look it up again. It's been a few years but the engineers were also surprised.

Smells are a very different. They spread differently from dust. Cigarette smoke is easily spread. The more humid the more pronounced. I have seen my dogs get excited after a rain. Noses in the air. I know it not scientific but they also have better sense of smell.

I was taught that low returns warm the floor. This and other research shown it has little effect and that the supplies when designed for proper throw is what effects the air in a space.
Wern't you gone for awhile?
I'll try to find the research and PM you.

[Juan Madera]

Proper humidity control is essential for dust mites as the Bear says.

That said, I installed Aprilair 5000 air filters on my own home's furnaces and in pollen season, the fans are kept on low circulation constantly... And it helps. These filtration systems are a HVAC installer job as it involves ductwork. I change the media once a year.

If your son is very sensitive, both dehumidifier and high efficiency filtration are in order.

Once in a while, the significant other decides to open a window for "fresh air" and lets in pollen and I suffer...

[Hvac talker]

We do have a substantial amount of clients with medical conditions which includes immune deficiencies, pulmonary disorders,...

As far as the mechanical part of improving indoor air quality we always achieved best results with incorporating a HRV (you will probably benefit more from an ERV) with a whole house HEPA filtration system. All the fresh air introduced from the HRV (ERV) is forced through the HEPA where it gets purified to a high degree before entering the home. HEPA filters were sized to minimum 1 ACH (air change/hr). Furnace fan needs to be ON.

This solution is not inexpensive but delivers results. Operating and maintenance costs are also significant, especially when VOC cartridge are being used.

[RoBoTeq]

I'd have to see these studies. There are so many studies out there that are manipulated "model" studies not based on actually tested physics that I am extremely skeptical about their results. Too many people doing so called "studies" to promote some sort of product or agenda.

Not according to modern studies. It's really very interesting. The studies are on the net. I would give a link but will need to look it up again. It's been a few years but the engineers were also surprised.

Smells are a very different. They spread differently from dust. Cigarette smoke is easily spread. The more humid the more pronounced. I have seen my dogs get excited after a rain. Noses in the air. I know it not scientific but they also have better sense of smell.

I was taught that low returns warm the floor. This and other research shown it has little effect and that the supplies when designed for proper throw is what effects the air in a space.
Wern't you gone for awhile?
I'll try to find the research and PM you.

[RoBoTeq]

As far as I'm concerned, this is one of the best methods of controlling air quality. Just make certain the building is slightly pressurized.

We do have a substantial amount of clients with medical conditions which includes immune deficiencies, pulmonary disorders,...

As far as the mechanical part of improving indoor air quality we always achieved best results with incorporating a HRV (you will probably benefit more from an ERV) with a whole house HEPA filtration system. All the fresh air introduced from the HRV (ERV) is forced through the HEPA where it gets purified to a high degree before entering the home. HEPA filters were sized to minimum 1 ACH (air change/hr). Furnace fan needs to be ON.

This solution is not inexpensive but delivers results. Operating and maintenance costs are also significant, especially when VOC cartridge are being used.

[Hvac talker]

Just make certain the building is slightly pressurized.

Very good point.

So many times I see furnaces installed with only the combustion exhaust pipe connected and drawing combustion air from inside the house. That will slightly depressurize the house and potentially bring air from the outside through cracks and crevices where in winter time the humid warm air meets a cold surface and bingo - condensation occurs which can lead to mold formation.

Don't be lazy and install the second make up air pipe to make it a truly direct vented appliance. Your customer will thank you in the long run.

[RoBoTeq]

Not piping combustion air to the outside is also one of my pet peeves, but so many techs just don't understand all of the "why's" for things we should be doing, so they cut corners because the equipment manufacturer says they can.

Outside combustion air for condensing furnaces not only prevents adding to the negative pressure of a house, it prevents contaminated indoor air from being exposed to the heat and condensate of the furnace, greatly reducing ignition issues and corrosion factors.

The tighter houses are made, the worst it becomes to allow the house to go negative pressure. Bathroom and kitchen exhaust fans, clothes dryers, central vacuum systems, radon mitigation systems, high hat lighting in the ceiling under an attic space, fireplace/stove chimneys and even attic access panels all contribute to negative pressure issues in houses. Outside air is going to come into the house one way or another; why not control and condition it?
I know! I'm preaching to the choir. I just hope some of the others in the congregation learn more about what we do and why we do it just from our conversation.

Very good point.

So many times I see furnaces installed with only the combustion exhaust pipe connected and drawing combustion air from inside the house. That will slightly depressurize the house and potentially bring air from the outside through cracks and crevices where in winter time the humid warm air meets a cold surface and bingo - condensation occurs which can lead to mold formation.

Don't be lazy and install the second make up air pipe to make it a truly direct vented appliance. Your customer will thank you in the long run.

[Hvac talker]

Outside combustion air for condensing furnaces not only prevents adding to the negative pressure of a house, it prevents contaminated indoor air from being exposed to the heat and condensate of the furnace, greatly reducing ignition issues and corrosion factors.

So true!

Anyone having a client which has a furnace with a single pipe installation and a flame sensor which fails more often then usually? Check if they store any household chemicals nearby, especially off gassing from laundry softeners are known culprits to cause havoc.

[CoolAir Inc.]

Have you ever considered switching to ductless mini split system?? As you live in high humidity area and also dealing with allergen issues that are very common in high humid areas then mini split can be a solution as it has inbuilt dehumidifier and it also ventilates and cleanse the air from allergens. Mini splits are coming with anti microbial filters that prevent bacteria to spread in the air. You can install it in your son's room and your entire house. It cools in the summer and you do not need furnace heating in the winters as it also contain heat pump. So, you can use it throughout the year without worrying about cleaning the ducts. The washable filters keep the air quality to the highest.