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Old 02-18-2012, 03:49 PM   #1
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american standard freedom 90 UV light wiring


I have a Honeywell UV 100A light in the return duct on my Freedom 90.

As installed by the heating technician, light was on constantly since it was plugged directly into the wall. I thought this wasteful and I wanted to change it so that it would be on only when the system was running.

So, I purchased a separate fan relay with 24v coil, wired the 110V side in series with the UV light power cord, and connected the 24V side to (W1) Heat contact and (B) common. Works great -- now when the call for heat comes on, the UV relay gets 24V power and the UV light comes on.

Now I want to take it 1 step further so that the UV light relay will get 24V power any time the system fan is running, whether that is Heat mode, AC mode, or just the fan circulating. Unfortunately, I don't know where to tap in to the controller board to get that "fan running" signal like I did with the heat signal.

My first thought was that the "G" fan terminal would be hot any time the fan was on, but that is not the case. "G" is hot only when the fan alone is running in circulation mode.

I suspect that there is a system fan relay to control the fan in any of the modes and that I should be able to piggy back the "fan on" signal, if I could just find it.

Any help?

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Old 02-18-2012, 04:04 PM   #2
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american standard freedom 90 UV light wiring


Have you considered a sail switch?

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Old 02-18-2012, 04:13 PM   #3
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american standard freedom 90 UV light wiring


I actually did not know of sail switches until you mentioned it... Just googled "sail switch" and it looks like a good match for this problem and I will likely install one. Thanks.

Still, since I've been puzzling over this for a week, it would be good to find the electrical signal that I've been searching for.
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Old 02-18-2012, 04:20 PM   #4
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american standard freedom 90 UV light wiring


All the manufacturers literature I have read on UV lights dictates they be run 24/7 because they must saturate the are long term to work.


Is yours different?
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Old 02-18-2012, 04:29 PM   #5
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american standard freedom 90 UV light wiring


UV light can only treat air that it passes through. If a return duct has no air flow, then it is just leaving a light on inside for no reason. AC coils in supply ducts are a different story due to the condensation.
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Old 02-18-2012, 05:12 PM   #6
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american standard freedom 90 UV light wiring


Air is always moving through the system, where or not the blower is on. The air flow may be so low you can't detect it, but its there.

Its also harder on the ballast and tubes for them to cycle on and off.
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Old 02-18-2012, 05:22 PM   #7
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Perhaps that is so.

However, I wrote with a specific question about wiring and that is the only piece of information I'm looking for.

If you have that information, please share.
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Old 02-18-2012, 05:29 PM   #8
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american standard freedom 90 UV light wiring


Quote:
Originally Posted by bryandavid View Post
Perhaps that is so.

However, I wrote with a specific question about wiring and that is the only piece of information I'm looking for.

If you have that information, please share.
Well, you might as well not use them at all if you are going to circumvent the the way they are designed to work.


Must be a full moon today....
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Old 02-18-2012, 05:36 PM   #9
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There's always some clown who has lots of advice, but is unable to answer to the question. I suspect you exhibit that behavior during any phase of the moon.
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Old 02-18-2012, 05:40 PM   #10
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Yeah, but my UV light IS wired right.
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Old 02-18-2012, 07:19 PM   #11
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american standard freedom 90 UV light wiring


Quote:
Originally Posted by bryandavid View Post
Perhaps that is so.

However, I wrote with a specific question about wiring and that is the only piece of information I'm looking for.

If you have that information, please share.
Perhaps someone else will then answer your question on how to do this simple thing. However, I won't. The same as I wouldn't tell someone how to circumvent a safety.

Good luck.

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