Had our furnace and air ducts cleaned today for the first time in years; could have spun an entire dog from all the embedded hair.  The serviceman tried to upsell me with both a new reusable filter (to get 94% of the airborne substances), and a UV light to be installed in the furnace to get the other 6% worth of mold spores, bacteria and no-seeums.  I bought the filter and also a thorough cleaning of the furnace, but am waiting to decide on the UV light--another $400--until I can determine if this will really improve our indoor air quality.  The house is 1000 sq ft, one dog and two dogwalkers live there.  Any opinions?  One dogwalker (me) has asthma.  I couldn't find any research from a casual googling.

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I agree with Bob about 4" pleated filters, but would add two criteria.  First, you will want a MERV rating of 10 or higher to ensure you're trapping small enough particles to guard against asthma.  Second, you should consult the filter manufacturer's specifications to be sure that the pressure drop across the filter will be no greater than a few tenths inch water column at the filter face area and air flow velocity of your furnace.  Pressure drops higher than this will penalize the furnace's output efficiency (actual vs. nominal BTU/hr delivered) and could shorten the life of the heat exchanger.

Even the Merv 8 filters are MUCH better than just about any 1" filter you can buy. No they don't catch everything, but static pressure drop is much lower. With Merv 10 filters you need 2 of them to keep static reasonable unless you have a small HVAC system. 4" Merv 8 media is under $10 at our local supply house, Merv 10 is special order. Now if somebody would make 4" media filter cabinets for a reasonable cost then more HVAC contractors would install them.

$400 is over priced.

 What you should know about furnace filters is that they should only do a marginal job of removing air borne particulates.  The more you filter the more you restrict the air flow and hurt the efficiency of your furnace.  Those expensive 1 inch filters start out restrictive and only get worse as they get dirty.

If you look at a 4in filter they are not super efficient but they provide a lot of area so they last long.  One brand I see is either a merv 8 or 10 depending what box is checked on the side of the filter.

I recommend a mid level filter, about a merv 8 to 10 for a balance of air flow and filtering. The 94%  filter is probably a merv 8.

For UV lights, they are meant to work in conjunction with a filter.  They will kill the smaller mold spores that though a filter and also kill airborne viruses and bacteria that arent filtered.  They are very safe as long as you dont have direct exposure to the light, contained in HVAC system.   They are used in hospital operating rooms and food processing plants.  They are also used to purifiy water. Anything over $250 is probably over charging.  Also the bulbs must be changed every year as the UV output declines even though they will still put out light.

If you are looking for better filtering get a good  room air purifier.  I sell Austin Air room air purifiers.  They have a very good and long lasting HEPA filter and a very large charcoal filter.  The filter should last 5 years.


Indoor air quality starts with a lot of things!  The last item you do is filter.  Why allow everything into your home and then try to find it and remove it.  

Large High efficiency filters at the air handler create more problems then they solve.  If you got stuff in your duct work, and it is not moving, it isn't much of a problem.  EPA does not recommend Duct Cleaning for indoor air quality.

In Floor returns should have a filter at the floor.  This will not effect the static pressure of the duct system. If your dog is putting a lot of hair there.  Keep it out of the system to begin with.

The only time to worry about Mold Spores, is when you add water.  Keep the water out. Mold spores are not an issue. There are more mold spores in the bag of compost or mulch you spread outside on a Saturday, then in your home. Until you add water, they don't cause you a problem.

The 4" 8 MERV air filters are low cost, and have good static pressure ratings. There's no reason NOT to use them unless it's difficult/expensive to retrofit a 4" cabinet into the system. IMHO they should be standard on new installations. The 1" fiberglass filters that protected the 8 fins per inch A-coils of the 70's aren't adequate for todays high efficiency coils.

Try Clean Air Heat to analyze the best condition. I have Amana furnace and it works quite well, For duct cleaning I recommend in a year at least and if there are pets in a home so it should be asked for any good expert.

UV light is a recent technology to get rid from pollution. To get fresh air we can use it in air conditioner. It has many other uses too. But I don't know is it really that helpful. I works for a company named Air Care UV. This company produces many UV light based products. The products are helpful in many ways. For the product details visit the page UV Light Air Purifier. Hope this will help to know that kind of products.

Hello Tal segal,

Thank you for your replay. We always try to help our valued customer with good products in reasonable price. If you feel any difficulties in using our products please contact us. It's a great news to hear from you that our product helped you to keep your heath sound. Take care . If you think you need to update your product or you need to know about our other products then visit our site. UV Light Air Purifier .

Thank you again for the great replay.


This is the best UV Light in the market the Clear Blue Master.


The best UV Light system you can find on www.tmsuv.com

The give Lifetime warranty on the ballast and 1 year on the bulb.


The best UV light is the one NOT unnecessarily sold to unwitting clients who simply don't need them!

We've been in business 5 years and so far never installed so much as a single UV light. Unscrupulous competitors send out preventive maintenance techs at near minimum wage...the only way those guys feed their kids and keep the lights on is to upsell UV lights at wildly high markups. It is an unscrupulous, piratical practice and should not be tolerated.

If a client brings us advice IEQ from their allergist or other qualified health care practitioner, we would work with that pro to select and deploy recommended IEQ enhancements. No one should be buying this stuff on the advice of an HVAC contractor alone.

UV Light is working very well and been tested in Universities, its help to keep the air and the air handler clean from mold and bacteria..


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