Help of small wiring project.

[cdestuck]

My friend has a greenhouse that I had put a 24” ventilation fan in. A single pole switch between the fan and breaker box, 20 amp breaker. So he bought this thermostat to automatically turn the fan for cooling when temps in 100 degrees.

So in the single pole switch 2x4 box, I’m planning to run a piece of nm wire from the box then into this thermostat. Before the sp switch I was going to take the black hot wire and tie it to the black wire of the nm going to the thermostat, and the white wire to the screw on the sp switch.

In the thermostat, I was going to attach the black wire to the “line in" screw and the white wire to the “Cooling”red wire terminal. Of course I know to put some black marker on the ends of the white wire. And the ground to the ground screw and grounded in the sp switch box. Is my thinking on this correct? Thanks to all.

 

[Snoonyb]

Why not simply eliminate the switch?

 

[cdestuck]

Why not simply eliminate the switch?

I could do that but it makes a easy way to eliminate the power to the fans when the greenhouse is not being used. Simpler than finding the correct breaker in the panel.

Trying to find out if my assumed connections are correct.

 

[bud16415]

I think you have it correct there are just two ways it could be wired. There is a common and a NO and NC set of contacts. Normally Open / Normally Closed. If you want something to start when it gets too hot use the NO if you want it to shut off use the NC.

Wire it in series with your switch you have now so the switch will override the T-stat switch. As long as the T-stat switch is rated for the fan voltage and current you should be good.

 

[Snoonyb]

As stated, your proposed connections are correct.

I'd simply eliminate the switch, and simply adjust the thermostats as needed, rather than shutting off a breaker.

 

[bud16415]

Around here greenhouses can be used anywhere from a few months per year to year round and venting is changed during different times of the year. In the winter no fans are used and heaters regulate the temp mostly at nighttime. In the spring they will overheat during the day hours and it is still too cold to open them fully like they do in the summer. That’s when the fans get used the most. In the summer they open large windows and doors and leave them open as night temps don’t get to low.

The idea of the switch would be for 6 or more months a year when the fans serve no function.

 

[Snoonyb]

YEP, why not have 2 devices, instead of one, too control a single appliance.

 

[bud16415]

YEP, why not have 2 devices, instead of one, too control a single appliance.

From the info he posted I didn't see where the T-stat had a built in override switch. The breaker could be used if nothing else is on the circuit and many farm don't want the workers messing around in the breaker box or turning off the wrong thing. Even with the switch I would label it so someone doesn't assume it is a light or something.

 

[Snoonyb]

Link; https://www.qcsupply.com/media/product_attachments/attachment_file/1/0/10032_Eventherm_TH520_IOM.pdf

40-105 F range, so I guess in PA the switch would be necessary.