Slowing fan on Miller Furnace

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Old 10-11-08, 06:16 PM
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Slowing fan on Miller Furnace

About 3 years ago, I reducted my home. During that time, I reducted my wood furnace to have it in series with my LP Furnace. I use my LP furnaces blower to push air through the wood furnace. What I was wondering is, Right now from the limit control I use r and g to energize the circuit board on the LP furnace to push the heat from the wood furnace. It defaults on high, or fan on position. I was wondering if there is a way to slow down that blower when the wood furnace needs it. Its a Miller furnace, about 15 years old, it has maybe 4 years use on it, due to us burning wood and not using the furnace as often. Thanks
 
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Old 10-12-08, 06:40 AM
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Do you have A/C on the system? If you don't then you may be able to slow down the blower.

Look at the control on the furnace, and see if there extra blower motor wire in "Park".. or something like that, and look at the wire diagram showing what color wire is for what speed. If it turns out High speed is set for cool speed, thenn drop it down to a slower speed on the "cool" tap.
 
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Old 10-12-08, 07:56 AM
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I don't have ac on the system. I'm not exactly sure what you are saying though? Is the default on for the blower for a/c if I had it? I will look at the control board. What you are saying is change the fan speed on cool on the circuit board, and this should slow the blower....? Instead of r and g, could I use the 2 wires somewhere else to use the cool side so I don't use the Blower on?
 
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Old 10-12-08, 08:27 AM
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The R and G is fine on what you are doing, and since you don't have A/C, you can change the blower speed that is on the "cool/fan on tap"

What is the model # of your furnace?
 
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Old 10-12-08, 09:05 AM
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The model # is G3RC120C-20 Thanks
 
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Old 10-12-08, 09:14 AM
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Must be an older model, I am not able to come up with that model #.

Is there a wire diagram on the furnace? If there is are you able to post a photo of it on here for us to see?
 
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Old 10-12-08, 10:18 AM
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http://i295.photobucket.com/albums/m...9/manual-1.jpg
 

Last edited by laynes69; 10-12-08 at 10:44 AM.
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Old 10-12-08, 11:44 AM
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Did this used to work the way you have it rigged, with that LIMIT switch on the wood stove to ENERGIZE the LP controls?

I'm trying to figure out how the wood stove's LIMIT switch would energize it. You'd think it would OPEN the circuit and shut it off.

What am I missing here? I pretty much follow the clever concept of what you have said, but the above eludes me.

It sounds to me that you really needed a temperature actuated fan/limit control on the wood stove and not just a pure limit switch.

What kind of wood stove IS this? Doesn't it have it's own heat exchanger with it's own blower in it?

And by defaulting on ON, do you really mean it does not come on? Or do you mean it will come on - but then go off sooner than a thermostat is calling for? If you mean the latter, then actually yes, the blower is shutting OFF likely due to it not burning hot enough, or blower too fast.
 
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Old 10-12-08, 11:54 AM
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I have a honeywell limit/control on the back of my wood furnace. When it hits 140 the 2 wires coming from the control complete the circuit and the lp furnace blower kicks on. When it hits 85, its off. Its a 1500 usstove wood furnace. I didn't like the 2 tiny little blowers, so I modified the firebox jacket to accept more airflow for a series install. By energizing r and g, I get the default blower speed of high, I don't want high for the wood furnace, I want medium, or low. Just so it slows the air around the firebox. Its a very simple setup, but I have had to explain it in detail to every hvac person who has came out for estimates on a new heating a/c system.
 
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Old 10-12-08, 12:01 PM
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Thanks for the explanation. Makes things now easier to understand.
 
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Old 10-12-08, 12:02 PM
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Thanks for the Photo!

switch the Orange and Black wire around.

E,

He has the fan/limit combo control on his stove, instead of line voltage going to the fan control, he used low voltage instead.
 
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Old 10-12-08, 12:07 PM
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Originally Posted by Jay11J View Post
E,

He has the fan/limit combo control on his stove.
That's what I had mentioned in my first previous post. That all makes sense now. Interesting posting. Laynes sounds like the inventor type.
 
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Old 10-12-08, 12:39 PM
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I changed them, can't hear a difference, but I will see when I fire the woodfurnace back up. What was them m1,m2,etc on the board? I knew the heat and cool. I did change my heat to med high, and I put low on the m1. This was the most efficient setup for the woodfurnace. If the fire dies, the heat will automatically kick on and run. Thanks for the help.
 
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Old 10-12-08, 02:11 PM
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The M's are just dead port to "park" the unused wires. If you wanted to, you could of used low for the wood stove instead, if you want the lowest speed.
 
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