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air filter

MERV Score for Indoor Air Filters?

What rating should indoor air filters have?  Many intake filters don't list the MERV rating.

Our Answer

MERV stands for Minimum Efficiency Reporting Value, and ranges from 1 up to 20.  The higher the rating, the greater a filter's effectiveness.  It generally doesn't take more than a few dollars per filter to jump several grades higher on the MERV spectrum.

I would say that, as a rule of thumb, go with a microallergen filter, which usually has a MERV score of at least 11.  However, if you want to hone in on more than just ratings, there's a whole line of Filtrete air filters that can weed out various particles depending on your intended result, such as reducing odors or allergens.

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Basement Odor

My mother's house has had an odor in the basement for the last 2 summers.  It is NOT sewer gas - which is everyone's first suggestion.  It smells like cat urine, but there is no cat.  The odor is not there in the winter - whether the smell is gone or the furnace removes it, I can't say.  The smell is worse during/after a rain.  We have had the plumber, who cleaned out the sewer pipes, etc, and found nothing else wrong.  I had the borough engineer out, who was unable to offer any ideas.  It seems to come from one corner of the basement floor, and sometimes the bare concrete is dark, as if water is leeching up from the ground.  There is never a puddle.  We have already tried the enzyme odor removers - to no avail. We are having the tile floor removed and will have the concrete painted with an epoxy paint, but don't want to do the work if the smell will still be able to get through the paint.  Anyone have any ideas?  Thanks!

Our Answer

It is rare but sometimes fiberglass insulation develops a urine-like odor from amines that are used in the adhesive manufacture. Moisture exacerbates the emission.

Pull some of the fiberglass out and put it in vegetable steamer and see if it smells after you heat it up in a humid, hot environment.

Don't spend any more money on "remediation" until you are sure of the problem.

And let us know if it's the fiberglass.

Jeffrey May

May Indoor Air Investigations

Author: Jeff May's Healthy Home Tips

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floor, cleaning, dust

Why Is My House Always Dusty?

When I dust my house in the evening, everything is covered again by the next morning.  Could the problem be stemming from the heat pump system? We've had the unit thoroughly cleaned inside and out, to no avail.

Our Answer

Consider upgrading or adding filters to your HVAC system to reduce the dust problem and improve air quality.  Filtrete makes a range of filters customizable to various issues from excess dust to allergies. However, your best solution - albeit a more expensive one - is an electronic air cleaner that can remove even virus-sized particles from the air.  It's mounted on a return duct and protects your home from mold and pollen - and will do a number on that dust!

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deck stairs

How to Get Rid of Dust

I have a 3 year old home with vinyl windows which are tight. There's weatherstripping around all the doors and I can not figure out how this house gets so dusty within a matter of a couple days. Wondering how to get rid of dust.  How do I find the source of my problem?

Our Answer

Well, we hate to be the first one to tell you but the culprit may not be outside but INSIDE the house!  We all generate a lot more duct than we realize and reducing it starts not on line with cleaning surfaces likes rugs or furniture, bit more importantly by cleaning the air.

We'd suggest that you invest in a good quality electronic air cleaner.  This type of system is installed into the return air side of your heating/cooling system and cleans the air thoroughly each time the system is on.  The best EAC's can even remove virus sized particles.

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Dust in House: How to Reduce or Remove

I have noticed an excessive amount of dust in my home; especially in the master bathroom.  It seems like I can't keep the furniture dusted enough.  When I rinse the tub there is a coating of lint type dust that isn't visible until I rinse the tub by pouring water on the sides of the tub before filling it.

I am wondering if there is a leak in our attic and perhaps the vent fan in the bathroom is allowing air flow from the attic to enter my home.  I haven't had the attic inspected but the house was built in 2003 so didn't think I would have a problem.  It is frustrating to try and keep up with the dusting!  Have you heard of anything like this? What can I do to solve this problem?

Our Answer

While it’s possible that you’re getting some dust from the attic, it’s unlikely. If there are gaps around your ceiling fans, air is probably moving from the house into the attic, not the other way around, due to something called the stack effect. I suggest that you look at a couple of other possible sources of dust first.

When’s the last time you had your clothes dryer vent cleaned? If that vent is obstructed, you could be getting a lot of dryer lint blowing back into the house. Turn on your dryer, then go outside to find the vent opening. You should have a nice, strong flow of warm air coming out of that opening. If you don’t, then have the vent cleaned to remove any build up of lint. It might solve your problem and make your dryer work better at the same time.

Do you have a fireplace or wood stove? If you do, and the inside of your house were to become depressurized, air could move backwards through these flues and carry ash into the house. If this is the case, you’ll need to find out why the house is becoming depressurized. Leaky ductwork in your heating system is often the culprit here.

One other thing to consider is that your heating system’s filter is missing. It’s important for you to clean or change your air filter regularly.

Editor’s Note: Jim Katen is a professional home inspector with Benchmark Inspection Service in Gaston, OR. Jim volunteers as a guest expert in The Money Pit Community. Learn more about Jim’s work through the American Society of Home Inspectors.


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White Dust in Crawlspace: Is It Mold?

My house filled with a dust-like material/powder when I first turned the heat on last fall. My HVAC and pest control people do not know what it is. It is covering all surfaces in my walk-in height crawl space. There has been no drywall work done recently, or any other projects.  It is not sugar white but ivory white. It has not been pulled into the living space that we can notice since the first time. Any idea what this might be?

Our Answer

This is an unusual scenario.  Since crawlspaces are completely separate from living spaces, they don't usually develop dust like you described. 
There is a possibility that what you're seeing is mold.  There are many types of mold, and some can grow on wood surfaces, like framing, and look like white dust. 
So the first step is identify whether this is, indeed, mold - and if so, what type it is.  I recommend having your space inspected by an experienced professional home inspector.  The advantage of a home inspector is that they're not there to sell you any particular service -  unlike, say, a waterproofer or HVAC contractor or any contractor who's hoping to land the job.  A home inspector doesn't have such motivation, which works in your favor. 
Find a home inspector who specializes in mold.  Know beforehand, though, that even the most knowledgeable home inspector will need to take a sample of the dust and send it to a lab for analysis.  The steps to resolve the problem can be determined once those results come back.

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Can I Put a Filter on a Floor-Mounted Return Register?

Is it wise to place a vent filter in the vent of floor-mounted return register to both filter the air and to prevent stuff from falling into the air duct?

Our Answer

I've never seen individual filters used to keep debris from falling into floor-mounted registers. They're typically easy to remove, and the occasional reach down with a vacuum or cloth - or just your hand - should be enough to keep floor registers clean. 
Filters are used exclusively on the main return duct, and that's usually either at the main return (typically centrally-located in the house) or inside the furnace, on the return side of the blower fan.  Filters remove allergens and germs from the air, perhaps even limiting the amount of dust that makes its way into those floor-mounted registers. 

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Will UV Lights Kill Mold?

I had mold last two times they came to service airconditioning unit. We bought and installed an UV light to stop mold. Is this a legitimate remedy or a scam. Have to replace light once year.

Our Answer

UV lights MAY help kill mold spores and other contaminants.  It depends on the intensity, reflectivity and installation, which should be near the evaporator coil.

When I hear "they found mold" I'm also leery --- too many contractors yell mold when in fact it can just commonly be algae, or even dirt.  Mold should be tested by an independent lab before any corrective action is taken, other than simple cleaning of small amounts.

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How to Reduce the Dust Level in a Home

There is a fine dust that seems to be coming from the heat pump that gets on everything. The heat pump has been looked at and cleaned, and no one can find any problems. Any ideas? Thanks.

Our Answer

Basic fiberglass air filters do very little to trap dust and fine particles. It may be wise to consider investing in a high-efficiency electronic air cleaner. They can trap even virus-sized particles, and can certainly handle dust.

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Mold Growth Due to Air Conditioning System

If your System is over sized the air is colder. system runs a Quicker or cooling the air too fast not removing Humidity. Higher Humidity turns to Mold. The Air conditioner units cool the home and set the humidity level never turn off a vent in a room if your not in it. This make the Out Door heat and humidity enter the room. If you have return Air Vent in this room your pulling in hot air making system run longer.(I CAN BEVEIVE MONEY PIT SAID TURN OFF VENT IN ROOM'S YOU DO NOT USED)this IS INFO FROM 1970'S. And is not true. I keep my temp at 74-75 all the time if your not home the system runs shorter time due to no one opening doors. Now if a system is over charged this make evap., coil to cold too making mold in duct work. To Large system and under sized return in 99% of home's.

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Best Product to Clean and Prevent Indoor Mold

1. What types of health effects have been experienced by inhabitants of a home where high concentrations of mold exist?

2. If cleanup of mold is needed, can a combination of wiping with a bleach solution and then applying Microban be as effective as using a biocide, which may be toxic?

Our Answer

According to the CDC website, exposure to mold indoors has been linked to upper respiratory tract symptoms, cough and wheeze in otherwise healthy adults and children, and asthma symptoms in people with asthma. It has also been linked to hypersensitivity pneumonitis in individuals susceptible to that condition. For indoor mold cleanup, we would recommend a product called Concrobium. There are lots of benefits to Concrobium. It's safe for any surface, including fabric. It leaves a protective barrier when it dries. Bleach doesn't do that, and bleach is also not fabric-safe. Bleach will kill mold spores on application, but unlike Concrobium, it doesn't offer any ongoing protection.

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How to Reduce Home Humidity

We installed a HVAC system (16 SEER) last year and now we can't get the inside humidity below 40%. (Humidifier is disconnected.) Any ideas?

Our Answer

Generally speaking, AC systems make lousy dehumidifiers. They do dehumidify, but they do so as a condition of cooling your air. Here's how it works. AC systems take warm, moist air, and cool it. Water is released when that happens, which then gets collected in a condensate drain and pumped out of your house.

Your new, more efficient system is going to run less, by design, than your old system. The fact that it's running less means it's not moving as much air, so it's not dehumidifying as much as your old system. A more permanent solution is a whole house dehumidifier. It's a separate piece of HVAC equipment built into the system. Some models can remove as much as 90 pints of water a day.

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Sewer Gas Odor in Bathroom

We've been in our home for about 4 years. A couple of years ago, we began to notice an intermittent sewer gas smell in the bathroom on the ground floor. It seems to coincide with strong winds. We are assuming that the vent pipe is cracked, but don't know how to go about repairing it. The other side of the wall which houses the vent pipe is a closet - and there's no smell at all in such a confined space. We've tried sealing all the gaps around pipes and electrical outlets coming through the bathroom wall, but the smell persists. We replaced the toilet and found that the old one did not make full contact with the wax ring. So we installed the new one with two wax rings stacked to make sure we had a good seal - but the smell continues. The bottom half of the wall is tiled, as is the floor. There are no gaps visible where they meet, and no baseboard to obstruct the view. Any other ideas?

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How to Reduce Basement Humidity

I live in northern Maine, and my basement is starting to get a weird odor. It's not getting wet and there are no water issues. A friend says I need to get a dehumidifier. The basement has our laundry area and my "man cave." I was wondering what kind of dehumidifier I should buy. I've seen some that have heat and AC. Will this type of dehumidifier help the rest of the house, or just the basement? Please recommend a brand and/or model.

Our Answer

A humid man cave sounds pretty unpleasant, so let's get that back into shape for you.

First of all, you're getting high humidity because of excessive moisture outside the basement. The fact that you're not getting water doesn't mean the problem doesn't exist. Moisture that collects around the foundation perimeter emanates into the basement because the foundation is very porous. The solutions to basement humidity don't begin with a dehumidifier. To address the root problem, you'll need to take steps to redirect water away from your home's foundation.

That starts with your gutters. Make sure your gutter system is properly sized for your house so you don't get a gutter that becomes overwhelmed. Keep the gutter system in good repair, and keep your gutters clean and free-flowing. As for downspouts, you want one for every 400 to 600 square feet of roof surface. And you want to make sure the downspouts are extended 4 to 6 feet away from the foundation.

Next, you need to address the grading of the soil around your home's foundation. You want the slope to drop away 6 inches over 4 feet. The type of soil that you add is also very important. Don't use topsoil -- use clean fill dirt. Topsoil is very organic and will hold water. Fill dirt, on the other hand, can be tamped down and packed in to get a solid slope that water will run over. After you have the proper grade established, then you can add a little topsoil over the fill dirt to plant some grass seed or put some mulch or stone or whatever you want.

As a last step, after you've done everything you can to keep water away from the foundation, you can add a dehumidifier in the basement. Find one that has a condensate pump either built in, or as an accessory. Otherwise you'll spend a lot of time emptying the pan.

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Will Closing Closet Doors Save Me Money on Air Conditioning?

Should I keep my closet doors shut when the air conditioner is running?  Will this help keep cooling costs down?  

Our Answer

Generally speaking, any non-climate-controlled spaces you can close off -  including closets - has the potential to lower your home cooling costs.  The reasoning is simple: Any added square footage forces air coming out of the HVAC system go a longer way to achieve the desired room temperature.  
One exception might be if the closet is damp.  In this case, it would be good to have dryer air flowing through it so that clothes and other fabrics stored in there don't get moldy.  This could also be accomplished via louvered closet doors, which let some air circulate through the smaller space.