Trane 4TFE VS AHU with UltraViolet Light Metallic Burning Smell


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Old 06-26-08, 04:27 PM
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Trane 4TFE VS AHU with UltraViolet Light Metallic Burning Smell

I just had a new Trane 4TFE VS AHU installed about a month ago. I went ahead and bought a UV light (Bio Fighter Lightstick 14" 24 V non-ozonating type) and installed it facing the evaporator coil. I would like to keep everything shiney, new and mold free.

I have noticed a metallic burning smell coming out of the AHU, especially if it's cooler outside and the air hasn't run for a while. The light is on 24/7. There is nothing obviously wrong when doing a visual inspection. Where is the smell coming from???
 
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Old 06-26-08, 05:46 PM
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Actually not sure.

I'd turn off the light for a few days and see if the smell goes away.

Why are you running the light 24/7 and not the fan also? The light has a life time like 10000 hours or what ever.

I would either run the fan 24/7 as well or only run the lite when the fan is on.
 
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Old 06-26-08, 07:07 PM
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Sorry to here you are having a problem! UV lights will not keep your unit shiny and clean. Only servicing the unit will do this, Also the light will only give you mold prevention on one side of the coil. To do it correctly you will need to lights. That will cost a lot of money in bulb replacements. I tell my people that there money is better spent on a service contract.
 
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Old 06-26-08, 07:30 PM
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Thanks for replies...

The manufacturer's recommendation is to run it 24/7. Running the fan continuously bumps the RH up from 45% to 65%, which defeats the purpose of having an air conditioner... Unfortunately another UV light on the front side isn't an option, as the AHU is installed in a closet and the UV light would be visible. Another thing is that the filter is installed right against the evaporator coil. Perhaps an arrangement like the one shown below would work:

http://www.freshaireuv.com/fauv-filter/index.html

The fixtures and bulbs aren't too expensive if you know where to shop. I think it's worth having an AHU UV light to kill mold and it certainly doesn't hurt to use HEPA-type pleated filters and to have your system serviced annually, too.

Anyway, back to my quandary... Where is the burnt metallic smell coming from? Is there some inherent interaction between the UV light and something in the AHU?

The only plausible idea I have is that the 24 VAC stepdown transformer is running hot. The light draws about 1 A but the fuse is 5 A so it should be OK... I'll check the next time I have it opened up.
 
 

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