Wiring thermostat to control 110v swamp cooler


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Old 08-03-16, 06:01 AM
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Wiring thermostat to control 110v swamp cooler

Hello, I am wanting to wire my swamp cooler into a new thermostat but need some help. I know very little about wiring and have gathered some information but would like experienced users to check my logic.
The swamp cooler has a 2-speed motor, therefore I would like the thermostat to control both speeds using Y1 and Y2 terminals. As far as I know 2 stage thermostats will apply power from the R terminal to the Y2 if more cooling power is required at the same time power is applied from R terminal to Y1. I also want the water pump to work every time the thermostat calls for cooling (for both speeds)
I have found that the Honeywell RC840T-120 might allow me to use the 24v thermostat with the 110v swamp cooler and using a SPDT relay I could connect Y1 and Y2 to the 2 terminals of the 2-speed motor. Honeywell RC840T-120 was created to connect line-voltage controlled heaters to 24v thermostats but I think it will also work with the swamp cooler. This device will be the first relay that will decide if the pump and motor are going to receive power. last realy is the one that will control the power to the motor based on Y2 terminal from thermostat. The thermostat will send power to Y1 only for 1st speed and in case it needs more cooling power it will start sending power to Y1 and Y2 at the same time causing the SPDT relay to switch power to High through terminal 3 as the following diagram shows:
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Old 08-03-16, 10:15 AM
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Welcome to the forums.

On your two speed motor..... it's one speed or the other. Hi and Low don't get powered at the same time. That relay you show gets energized in Y2 to select hi. That's good.

The circuit will operate as you have described.
Just not sure how beneficial high/low operation will be.
 
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Old 08-03-16, 10:52 AM
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The thermostat documentation said that if after X(can set) time of not reaching desired temp it will apply power to the Y2. So kicking it into high gear or starting up another unit if that was desired.

Thank you for the input!
 
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Old 08-03-16, 04:22 PM
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By beneficial I meant running the unit on slow speed. I know the idea is to move the maximum amount of air thru the pads. I'm guessing you've already used it in the slow speed mode.
 
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Old 08-04-16, 07:51 PM
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Ahh yes. low seems to do the job most of the time, High is so dam loud that i tend to never use it. However having it on a thermostat and keeping a more steady temp i think will will be needed only on the hottest days.

Thank you again for the help
 
 

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