Wiring Humidifier to a Trane Furnace


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Old 10-31-05, 08:42 AM
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Question Wiring Humidifier to a Trane Furnace

Just installed Dessert Spring humidifier on a Trane XB80 unit using the plug-in transformer that came with the humidifier. How can I wire the humidifier/humidistat to the furnace so that it only runs when the heat is on?

As much details as possible would be appreciated.

Thanks
 
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Old 10-31-05, 02:35 PM
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Not knowing the full model # on your furnace, I am not able to look it up..

Some Trane has a HUM term on the control board, that hum power off 110volts to the transformer that you wire to it. When the unit calls for heat, ti will power up the transformer/humidifer.

If you don't have the HUM on the control, there is a current sensing relay to wrap up on the blower wire.
 
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Old 11-01-05, 03:52 AM
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The model number is TUE100A948L3

When you said wire to transformer, do you mean attaching wires to the plug of the transformer?

Thanks
 
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Old 11-01-05, 09:08 AM
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Do you have a plug on your transfromer???
 
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Old 11-01-05, 09:24 AM
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Yes, it's a plug-in transformer with 2 wires coming out of it. One is connected to the humidifier motor, the other to the humidistat.
 
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Old 11-01-05, 02:28 PM
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The wire going to the humidstat, and motor is the low voltage side.. What's on the otherside of the transformer?
 
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Old 11-01-05, 05:16 PM
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What do you mean other side? It's a plug-in transformer, just like for a cordless phone, except, instead of a connector it has 2 wires, stripped about 1/2" at the ends. One is connected to the humidifier motor and the other one to the humidistat using wire connectors. The humidifier motor and humidistat are also connected by a separate wire.

Also, the humidistat is Honeywell H8908b. It only has2 connections on it, not 4-5 like the Aprilaire does.
 

Last edited by Gennady1; 11-01-05 at 05:33 PM. Reason: Additional info
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Old 11-01-05, 07:57 PM
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Ok, This is new to me if this just plugs into the wall. I've never seen a Dessert spring system... I've heard mix reviews from others on this..

Anyway, then you will need to get a A50 current sensing relay, or a sail switch.
 
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Old 11-02-05, 03:47 AM
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I found a wiring diagram for the furnace. It has R, Y, G, W, C connections. Can I connect W to the humidistat and C to the motor and not use the transformer at all? The note says that C is only used for 24 V connections.

Thanks
 
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Old 11-02-05, 04:16 AM
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The easiest way is to get the current sensing relay and put it in series with the wire going to the humidifier. You put the sensor around the common wire for the blower. That way the humidifier will only operate when the blower is on.
 
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Old 11-03-05, 07:24 PM
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What is the output of the plug in transformer that came with the humidifer?

The current sensing relay won't work, as he said "When the HEAT is on"

Not when the fan is on.

If the output is 24 vac then you can wire itin like so:

Tie an extra wire to your W thermostat wire and run it to your humidistat.
run the other wire from your humidistat to the humidifier.
and the other wire from the humidifier to the C wire/terminal.

That should work.
 

Last edited by shank; 11-03-05 at 07:35 PM.
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Old 11-04-05, 06:38 AM
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Originally Posted by shank
What is the output of the plug in transformer that came with the humidifer?

The current sensing relay won't work, as he said "When the HEAT is on"

Not when the fan is on.

If the output is 24 vac then you can wire itin like so:

Tie an extra wire to your W thermostat wire and run it to your humidistat.
run the other wire from your humidistat to the humidifier.
and the other wire from the humidifier to the C wire/terminal.

That should work.
Shank,

It could work. but lot of time. lower end equipement don't have transfromer large enough to handel the load to run the humidfer. So that's why Matt and I are suggestion the A50 relay.

If you put the relay on the Common Wire. then yes it will work.. But if you put it on the heating speed wire, then yeah. it won't work.
 
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Old 11-04-05, 06:42 AM
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Thanks guys. I ordered the A50 and will try it this way. Will keep you posted
 
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Old 11-04-05, 04:30 PM
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Originally Posted by Jay11J
It could work. but lot of time. lower end equipement don't have transfromer large enough to handel the load to run the humidfer.
Now I don't claim to know alot about Trane units, but I wouldn't think I would call any of them low end.

How many amps does that kind of humidifer pull anyway?

Originally Posted by Jay11J
If you put the relay on the Common Wire. then yes it will work.. But if you put it on the heating speed wire, then yeah. it won't work.
I am not Familiar with this relay type, so excuse my ignorance, but how does it sense only the current in the heating cycle from the common wire? Seems to me it would sense current anytime the fan was running, be it cooling, heating, or continuous.
 

Last edited by shank; 11-04-05 at 04:43 PM.
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Old 11-04-05, 06:50 PM
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Shank. Yes the current sensing relay would sense current anytime the blower is on but that is where the humidistat comes into play. If their furnace just has a standard 40 va transformer on it they sometimes are just enough to run the airhandler and that's it, if it's a 60 va then it would probably be just fine.
 
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Old 11-04-05, 08:01 PM
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So it technically could come on with the air also.

The humidifiers we use will run on a 40va transformer no problem, ofcourse they are nothing but a solinoid anyway.

I didn't even konw a relay like that existed, never had a use for one.

Learn something new ever day.

Thanks.
 
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Old 11-08-05, 03:44 AM
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Just got the relay, but no matter what I tried I can't get the humidifier to work only when the furnace is on. I tried both connections.
1. Relay to humidifier to humidistat to relay.
2. Relay to transformer to humidifier to humidistat to relay.

In the first connection, the humidifier does not work at all. I guess I do need to use the transformer.

In the second connection, as long as the humidistat is on the humidifier comes on, even if the furnace fan is off.

What am I doing wrong?

One more question. Does the common wire need to be stripped of insulation before passing it through the relay clip?

Thanks
 
 

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