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Old 07-25-2012, 10:28 PM   #16
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New Boiler System Control with 2 stage Heat Thermostat


Thanks houston!

That helps a lot.

I dont have a seperate air handler but I get the idea. I can use a seperate relay to lock out stage 2 from coming on when stage1 is active. This is how its drawn in my second circuit.

I guess its ok to put power directly to the furnace fan since no one has said not to. The relay on the control board should be off so current shouldn't flow into it.

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Last edited by hartkem; 07-25-2012 at 10:32 PM.
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Old 07-25-2012, 10:33 PM   #17
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New Boiler System Control with 2 stage Heat Thermostat


Use the relay to energize the G terminal of the furnace.
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Old 07-25-2012, 10:48 PM   #18
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New Boiler System Control with 2 stage Heat Thermostat


I thought we were going to configure the stat for electric heat.

Quote:
I guess its ok to put power directly to the furnace fan since no one has said not to.
We do not want to risk energizing 2 speeds simultainuously.
If you will use a relay for fan control, use it on the low voltage side as beenthere has posted.
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Old 07-25-2012, 10:53 PM   #19
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Quote:
Originally Posted by Houston204 View Post
I thought we were going to configure the stat for electric heat.


We do not want to risk energizing 2 speeds simultainuously.
If you will use a relay for fan control, use it on the low voltage side as beenthere has posted.

He said about direct wiring the fan.

I would think setting stat to electric heat is the easiest way.
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Old 07-25-2012, 11:02 PM   #20
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Quote:
Originally Posted by Houston204 View Post
I thought we were going to configure the stat for electric heat.


We do not want to risk energizing 2 speeds simultainuously.
If you will use a relay for fan control, use it on the low voltage side as beenthere has posted.

Yeah I thought of that too which is why the second relay prevents that from happening, I think. It locks out stage two from coming on. My two stage thermostat will turn on stage 2 when a three degree temp difference exists. I don't want this to happen if I have hot water available from my wood boiler.
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Old 07-25-2012, 11:04 PM   #21
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Quote:
I would think setting stat to electric heat is the easiest way.
It would be safer as well.
A loose wire or tripped saftey could energize the fan in a different speed and damage the motor if high voltage were wired to a 3 speed motor with a separate relay...


An old furnace example...
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Old 07-25-2012, 11:20 PM   #22
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How would having the tstat in electric mode affect the stage 2 propane. Currently the blower comes on when the heat exchanger is hot enough. I suspect it would start the blower on a call for heat but what happens when the thermo disc in the furnace closes to turn the fan on.
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Old 07-25-2012, 11:24 PM   #23
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It would continue to run the higher fan speed.

Sounds like you actually have the old example that I posted.
If you do have this example, you could pick up high voltage after the fan center but before the fan limit and feed the same speed the fan limit feeds with a relay without the risk that I spoke of. (The 2 red wires in the example)

Last edited by Houston204; 07-25-2012 at 11:30 PM.
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Old 07-25-2012, 11:32 PM   #24
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Ok, I can activate the low voltage side. Is a DPDT relay capable of switching both 24 volts and 120 volts at the same time to control the G terminal and the circulator pump? Is there a way I can interupt stage 2 signal from coming on when stage 1 is active?
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Old 07-25-2012, 11:40 PM   #25
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You can make your relay control 2 other relays but you will need an additional tranformer at this point.

If you disconnect stage 2 when stage 1 is active, stage 2 will never run unless you use a separate temperature control to do this. (or a light switch)

Last edited by Houston204; 07-25-2012 at 11:47 PM.
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Old 07-25-2012, 11:56 PM   #26
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Originally Posted by Houston204 View Post
You can make your relay control 2 other relays but you will need an additional tranformer at this point.

If you disconnect stage 2 when stage 1 is active, stage 2 will never run unless you use a separate temperature control to do this. (or a light switch)

Ill have a thermoswitch inline between t-stat and relay for stage 1. I happen to have another transformer and more relays but im not following your verbal discription. Would you be willing to draw a diagram of it like above.

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