Reply to Thread

UV lights have been in use for decades. The first scientific tests were performed on b-coli in 1935. This is not really new tecnology. It is just the way that UV lights have been marketed is the problem. For example, I won't name a manufacturer but here is tidbit of a phone conversation with a manufacturer that I called last week. I called them regarding their claim of having the most powerful UV light on the market. This particular UV light was of the "stick light" type. I called their tech support to find out more information regarding their claim. I was told that there was no real test procedure that anyone uses to determine UV intenisity. The answer I got was "at the lamp I could be 30K microwats at the lamp and 10" away I could be 1K microwatts. There is just no definite answer for their claim as being the "most powerful light on the market." I also wanted to know where to install this light. On the box it showed a schematic of a furnace with plenum and return air drop. It showed multiple installation locations for this light. The one I was worried about was the notation that it could be installed in the return air drop. The tech told me no, do not install it in the return drop and that this particular light needs to be installed over the a-coil. He began to tell me of their other product to use in the return air drop

This is what is wrong with the UV marketplace. If we used UV lights in their proper application, we would all be better off. A "stick light" is meant to be an object purifier. It is not an air purifier!!! It slays me everytime I pick up a manufacturers little brochure and it shows biological contaminants flowing across a stick light and clean contaminant free air above. The stick lights are too weak and air is moving way too fast to do any damage. You may get lucky and have a mold spore or virus land on the lamp and eventuall it will die. When is the last time you installed a stick light in a return duct and got a referrel from them? Here is a link to UV dosage table to inactivate/kill different contaminants. I am not sure what the most powerful stick light rating is in the marketplace. http://www.americanairandwater.com/u.../uv-dosage.htm You can purchase a Lennox System in either 1500 microwatt or 2000 microwatt. Look at the table and see what 2000 microwatt kills. I didn't see anything on there. Did you? Also check and see what lamp replacements cost and frequency of replacement. Those dollars can add up.

I am particular to Sanuvox. Sanuvox markets their product how they should be marketed. When you purchase a Saber light, it is an object purifier. When you purchase an R+, it is an air purifier. The R+ is rated at 16000 microwatts of UV energy produced. Look back at that list and see what damage 16,000 microwatts can do on those contaminants. Theres a lot on that list that are killed on a 99% basis first pass. It is also very simple to install in return air drop, and has a 3 year lamp life. Seeing 3.5 to 4 years is not uncommon with these either as they are rated on run time. They will turn themselves on and off when the fan cycles off and on. The replacement lamps are also reasonably priced. No periodic maitenance either. Sanuvox also has the S300 which incorporates HEPA filtration and UV to get the best of both worlds and the P900 portable unit rated at 900 sq ft of air purification. They also offer an extensive commercial offering that can't be beat.

When considering a UV light manufacturer, do your research. Call and talk to them. As in my phone conversation above, you can print anything you want but when you talk to someone the truth comes out. Find a trusted manufactuer and a little change in the way you market these UV lights to the end user can drastically improve your UV sales and your bottom line. How many overflowing drain pans can you resolve this year?

We just started stocking the Air Scrubber Plus made by activtek. All the research is very convincing, but I'm doing my own right now before I reccomend one to anybody.

I'm not an expert on IAQ. But what our company recommends when there is a bad case of fungal growth is a duct cleaning(includes blower and evap coil), upgrading filtration to electronic or Merv 16 whole house filter and installing UV or UV/ozone air purifier. I've been told that a lot of the lights aren't strong enough to sterilize anything but what its shining on. But some of the newer lights on the market with a higher micro watt intensity are actually capable of sterilizing airborne bacteria/viruses. Especially if you have a long return and can mount them in the middle of the return so the light is shining on the air as soon as it enters the return. All the way to the light, and then all the way from the light till it gets to the furnace/air handler. I've heard great things about the ozone bulbs ability to get rid of odors. I have one customer that smokes constantly in her house. We put the UV/ozone combo in for her a while back and I came back to her house the other day. It didn't smell amazing but if I didn't know, I probably wouldn't guess the house was smoked in...

im am not a big fan of uv lights because as you can see in the picture they will only keep clean what its shining on. Ive seen where they actually keep coils mold free but what about all that duct work on both sides of the light......mold. If you have a customer that has bad allergies or whatever the case that they seek a uv light. I would refer them to new duct work or duct cleaning. I have never sold one to a customer just because the fact that I don't want to stand behind a upgrade that I truly don't stand behind. that's just my 2 cents though. Also most customers aren't going to like it when they find out that the bulb needs to be changed annually(in most cases) and they aren't cheap.

Originally Posted by ComfortService

We tried a duct cleaning along with a UV light but after 3 months the problem got better but didn't go away. Eventually we had to replace the unit and ductwork to eliminate the mold permanently.

Did you treat with any of the micro-biocides on the market? Complete replacement seems... extreme? I understand replacing pervious ductwork, but usually hard surfaces can be treated

CoolerGuy, beware of the claims of the REME. The test protocol related to the bacteria disinfection involved the inoculation of stainless steel coupons which were placed inside a controlled 3' x 3' atmosphere chamber equipped with an ozone producing lamp or Phi cell as they call it. And the fact that people believe this product reduces particulate is a complete farce. Unless you believe charged particles will avoid every other piece of furniture in your home and travel directly to the media cleaner to be collected. A great filter, a UVC light at the coil, and a means to reduce odors without ozone, using charcoal filters or some other method, is the best way to help control contaminates in a home.

new construction duct/return leakage to 5%
existing is harder..less access to some areas, but 10% average on existing duct/return.

energy_rater_La;

on one job, the guys bragged that they used 8 gallons of mastic.
(HO bought through Home Depot...need I say more?) the amount of duct leakage
was reduced from 300 cfm...to 200 cfm. but there were gobs of mastic all over
the place..they filled in the top of the sheet metal plenums...but not where the top
of the plenum attached to the sides..you know where the joint is! ha ha ha.

my advantage is that I test the ducts before and after sealing them.

not to bash the hvac industry...the job is to get it installed & running.
ducts are secondary for most.


just my pov

Can I ask what your test out numbers average?

"Eventually we had to replace the unit and ductwork to eliminate the mold permanently."


so....if the ductwork was well sealed to beging with
... uv light wouldn't have anything to prevent from growing.

it is a shame that mastics aren't used properly & the 'sealed' system isn't very well sealed at all.

I always find it funny that oversized,poorly cut holes for supply boxes that are hidden
by install of supply grill is so often over looked.
same for plenum to equipment connections, and return air..both ceiling mounted and chase.

code says mastic seal should be 'nickel thick' thats tough! I'm a pretty good mastic painter
and dime thick is hard. nickel thick takes some finesse.
I'm still trying to perfect that one!

imo if all ducts were mastic sealed, (I use both paint on and hardcast #1402 mastic tape)
and above mentioned areas were mastic sealed..then media filter is what works.

I've worked on lots of jobs..the problem solver aka 'my guys don't have time to do this kind
of work' I've found what works is painting the mastic WHERE it leaks.
making it nickel thick, and using a combo of both paint on mastic & mastic tape.
It isn't the amount of mastic you use, it is where you use it.

on one job, the guys bragged that they used 8 gallons of mastic.
(HO bought through Home Depot...need I say more?) the amount of duct leakage
was reduced from 300 cfm...to 200 cfm. but there were gobs of mastic all over
the place..they filled in the top of the sheet metal plenums...but not where the top
of the plenum attached to the sides..you know where the joint is! ha ha ha.

my advantage is that I test the ducts before and after sealing them.

not to bash the hvac industry...the job is to get it installed & running.
ducts are secondary for most.

electricians that have that same big oversized cut at bath & stove vent
fans & save a few $$ by buying IC recessed lights instead
of Insulation Contact Air Tight lights...they need to be responsible
for the holes in the air barrier for the attic also.

attic access/pull down stair cases...another leakage/heat transfer issue that
isn't addressed.

seems we seal walls pretty good, but sure like to make holes in ceilings!

I think on the same day that bath fan back draft dampers are installed
correctly (or at all) will be the same day that recessed lights
go out of style.

just my pov

I have found mold growth in units,with the customers reporting feeling very weak after leaving the home each day. We tried a duct cleaning along with a UV light but after 3 months the problem got better but didn't go away. Eventually we had to replace the unit and ductwork to eliminate the mold permanently. I believe UV can inhibit new growth and odor but does very little if anything for ridding existing mold inside the ductwork and coil.

We install a few UV lights and customers have really been happy with them. They have told us that they have helped out with alleges. We have been using Sanuvox.

http://http://www.master.ca/en/profe...feet&modele=R_

We always used uv resources equipment in the air handlers when I worked in mfg.. as said before keep all wireing you can away from the area, run the wireing in conduit or shield it some way and if you have to use zip ties make sure they are uv rated. they can also help design a system


http://www.uvresources.com/

well said teddy bear!

Any organic material that is high %RH for +24 hours has a high potiential for mold growth. Mold spores and organic dust are everywhere. A couple hours of drying out the ducts every 12 hours could stop mold spore from growing. A/c ducts in attics with moisture saturated cooling coils will keep the ducts near saturated for days on end. Completely drying out the ducts by operating the fan a couple hours twice a day stops mold. Fans in the "on" mode 24/7 are most likely to be clear of mold. There are other problems.
Also ducts in attics during cold weather also have mold potiential from condensation on the ducts when the duct surface is near the dew point of interior air dew point. Again operating the fan several hours each day will dry these surfaces and prevent mold spore germination.
Good indoor air quality requires fresh air change when occupied. An air change in 4-5 hours is usually adequate when occupied.
Air filtering to keep the equipment clean. Merv +11 is suggested for inside and fresh make-up ventilation.
Maintaining <50%RH throughout the inside of a home avoids mold and dust mites. Air ducts spend many hours with 80%-near 100%RH during cooling hours. Several hours everyday of <50%RH everyday will reduce mold/bacteria to minimable level.
In green grass climates, a whole house ventilating dehumidifier like the Ultra-Aire supplys fresh filtered air, blends the filtered dry air with filtered house air, circulated the conditioned air throughout the home via the a/c ducts. This procces maintains <50%RH throughout the all of the equipment.
In most cases the 100 watt fan of the dehumidifier can operate 24/7 which keeps everything dry during the "off" cycle. The real long term effects of UV lites on sensitive occupants is unknown.
Fresh filtered air, keep every dry when not in use, and low circulation is effective for indoor air quality.
Regards TB

Originally Posted by genesis

Gentlemen UVGI lamps are an excellent selection for surface irradiation. But a bad selection for IAQ. Their simply isn't enough time to deactivate a biologic moving at 500 fpm. If installed correctly they will do a good job of keeping the bio slime off of the coil which will maintain the heat transfer efficiency at the evap coil.

Additionally, if you do install one, insure that EVERY material within about 3 feet of the light is UV rated.

Some drain pans, ductboard materials, filters, filter housings, wiring, unit insulation, humidifiers, and virtually all flex duct inner liners will be degraded by exposure to UV lights.

Gentlemen UVGI lamps are an excellent selection for surface irradiation. But a bad selection for IAQ. Their simply isn't enough time to deactivate a biologic moving at 500 fpm. If installed correctly they will do a good job of keeping the bio slime off of the coil which will maintain the heat transfer efficiency at the evap coil.

Where installed properly (and everything else as well), they are pretty much scientifically sound.

To change the bulbs as recommended - expensive.

I can guarantee they will destroy anything not UV resistant in close proximity (humidifier panel trays).

I would only suggest if someone has extreme alergies.

Wow the UV light subject is defiantly a frustrating issue. Seems like to there is no consistency to anything regarding UV lights and everyone seems to have a different option. At any rate I was ultimately referred to RGF Guardian Air HVAC Cell and REME HVAC Cell. I was offered a substantial discount on the REME for my house so that I can experience it and then hopefully push the sales of them. Seems like this thing is adding peroxide, plasma or whatever to the air, which im not crazy about. Anyone else use these ?

Attachment 349221I usually steer homeowner towards sealing ducts & returns, then adding a media filter.

IMO, if everything is well sealed..there isn't anything in the duct system that needs uv lights.

that said...I replaced a ductboard supply plenum that had uv light.
everywhere the uv light could reach...no mold. where it didn't reach...mold.
so they do stop growth they reach.
if you look at the picture,
on the sides of the plenum..close to uv light...no mold. further on, where light
couldn't reach...mold.
the question to me alway was...what is causing mold?

in this case it was no seal at duct takeoffs at the plenum &
poor seal @ plenums to equipment.
condensation caused by hot attic air touching metal take offs
caused moisture inside (and outside) of plenum.
ended up changing most of the ductwork too, as mold had grown
inside flex.
plenums were changed to sheet metal externally insulated as per
homeowner concerns.

hope this helps.

UV Light For HVAC

Had a customer today inquire about adding UV lights to his duct work. Anyone have some good information as to the effectiveness of the lights ? What models are worthwhile? I do recall you have to be careful where you install them, flex connectors and filter media cannot withstand it. Should you have one in the supply and return ? Can all evaporator pans now a days tolerate it ?