# Fujitsu concealed unit wiring



## Shaft (Jun 9, 2009)

I wanted to know if anyone knows how to wire a 120V UV light and/or electronic air cleaner to an indoor concealed unit ARU12RML so that it only operates when the fan is running?


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## beenthere (May 30, 2009)

They would be wired and controled the same as any other 240 volt air handler would require.

How long have you been in the trade?


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## Shaft (Jun 9, 2009)

*Fujitsu/UV Wiring*

Thanks for the response,
You must have never installed this type of system or maybe you misunderstood my question. I'm trying to wire a 120V UV light to turn on only when the fan of the air handler turns on. This is a fujitsu ARU12RML concealed air handler. How lond have you been in the business?


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## hvactech (Jun 9, 2009)

It sounds to me that if the blower is a 240v 1ph motor, you could just tie your 120v UV lamp to one leg of the blower motor electrical leads. And you should know that, if you have any reasonable amount experience. By the way I've heard that the UV lamps will last longer if they are on continuously rather than the on/off situation. You probably never heard of a current sensing relay either.


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## Yuri (May 28, 2009)

I would call Fujitsu tech support for their recommendations. I took a course on their units and they are VERY voltage sensitive etc etc, especially the ECM compressor type. You should ask them as their units can get seriously messed up if you accidentally unbalance the wiring/backfeed anything.

Good Luck


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## beenthere (May 30, 2009)

Shaft said:


> Thanks for the response,
> You must have never installed this type of system or maybe you misunderstood my question. I'm trying to wire a 120V UV light to turn on only when the fan of the air handler turns on. This is a fujitsu ARU12RML concealed air handler. How lond have you been in the business?


 
LOL... Well, for what ever reason, I read teh first part of the model number, and thought of a different brand air handler.

But, it is wired the same way as you would for any air handler that uses 240 volts.

34 years for the record.


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## beenthere (May 30, 2009)

hvactech said:


> It sounds to me that if the blower is a 240v 1ph motor, you could just tie your 120v UV lamp to one leg of the blower motor electrical leads.


No, you don't do it that way either. Unless you ran a neutral.


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## Shaft (Jun 9, 2009)

*UV light wiring*

Thanks everyone but I was hoping for something I didn't know, this thing runs on DC in the air handler and I was hoping there was some sort of trick to it. I was was trying to avoid the current sensing relay but thats probably the way I need to go. My customer does not want it on all the time and I already explained to him that it works better longer if it was on continously. I have installed over 70 of these things and never had this type of customer request.


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## hvactech (Jun 9, 2009)

sorry shaft, I did not realise that this was a dc motor application. i am not at all familiar with the Fujitsu units, although I have some experience with dc motors in forced air furnaces. The current sensing relay may not be the way to go. If I can find a wiring diagram for that unit, I should be able to help you.


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## scooter (Apr 28, 2009)

Shaft 
Is this a ducted unit that you could install a low voltage sail switch into?
that way you could just use the sail switch to activate a relay/switch that would turn on the U.V. 
What brand U.V. are you using. I know that most of them have a very low A/C current draw. less then one amp so the equipment would not have to be big and heavy.
If you are not familiar with sail switches it is basicly an air vane in the duct that is attached to an external switch. it can be mounted in any position and most have terminals for normally open/normally closed. I think the last one I used was from EWC.
The 120 volt would have to come from another source so as not to disrupt your inverter system.
hope this helps 
Scooter


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