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Need advice on how to control commercial HVAC unit just past electronic timer control

RedBeard

May 13, 2017
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Joined
May 13, 2017
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Hello folks, this is my first post here just found the forums.

I have a little project I'd like to do, that requires me to control a commercial HVAC unit.
This unit functions by either turning on or off.
The temperature is set and I don't need to mess with it at all.

Currently the unit is setup on a timer (Part# EC7005PC/120) "Paragon" Manufactures this timer. (Wired to 120VAC)

This timer is setup and functions normally.

My father in law is requesting that he is able to override this timer remotely as this is located in a church and as a maintenance supervisor for the church he gets a lot of requests at the last minute to turn the A/C on.

My thoughts:
I'd like to use a raspberrypi or similar to control this unit with a simple on off switch command via the WiFi network.
Additionally I plan to use a google calendar account to override the timer, and take primary control of the timers purpose in controlling the HVAC unit day to day.
Ideally keeping the timer in place to use as a backup in case of network outages would be preferred.

So what I'm asking for here really, is any reason I should not go this route?
Thoughts, suggestion or concerns?

Additionally I'm not having luck locating the proper relays to handle the load I'm working with. Any suggestions much appreciated.

Here is a pic of the panel I took.
PflOiZG.jpg

I can sort out how to go about most of this, it's the 120VAC side that I want to make sure I do right. Ideas on wiring diagrams appreciated. Thanks for your time.

Finally since I'm doing this project for free, I'd like to keep my cost down for all required materials as low as safely possible.

I have been hasty in assuming I could use a relay for this, is there something more appropriate like a heavy duty contactor switch?
 
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(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,510
Joined
Jan 21, 2010
Messages
25,510
Yeah, you would want to use a contractor and have that installed by an electrician.

You can then use a rpi too switch the contractor. If the contractor requires AC, it is probably best to used the rpi to control the relay and have the relay switch per to the contractor.
 
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