Help wiring an STC-1000

[splitmelt]

I need a little help. I have just built a fermentation chamber, and need a little help wiring the control box. I have one of the Elitech STC-1000 temp controllers, and I know how to wire it for hot and cold, which is pretty simple. Basically just power going into the temp controller and then positive and negative going to either end of the duplex. Where I am having trouble is that I would like to add a couple of LEDs, for when the cold or hot is operating. Also, I wanted to add a power switch on the box to turn the whole thing on and off. I also heard that adding a relay is a good idea, to extend the life of the compressor on the fridge, and just for general safety. Unfortunately, I have no idea how to wire any of that into the basic build. Any help would be greatly appreciated. I can provide more info or pictures if necessary. Thanks guys.

[codewritinfool]

I'm not trying to be a dick, but after reading your post, there are enough basic conceptual problems with your terminology that you should consider letting someone wire it up for you. A few bottles of homebrew to an electrician friend keeps you safe.

This thing is AC powered, so there is no "positive and negative". There is, however, hot and neutral, maybe that's what you mean. Make sure you're never switching a neutral.
LED's can't be powered directly from 120 VAC. My suggestion is if you have outlets already wired up, plug a night light into the spare outlet.
Adding a relay won't do anything to extend the life of a compressor. The STC-1000's internal relay contacts are rated at 10A, so eventually you might burn them up. External relay(s) could have whatever contact rating you wanted, that's why some people consider doing it.

[Havanutha]

Electrician here...The unit already has an indicator light that will tell you if it is heating or cooling. Adding an additional relay would do nothing, it will be protected to the lowest amp rating...10 amps. It will blow the relay first, then your equipment anyway. It also has a power button. I am not sure why you are trying to fancy up this 10 dollar temp control...It already has all of the features you need?

[Steve Urquell]

I have wired 3 STCs from the diagram on this link:
http://www.homebrewtalk.com/f51/stc-1000-a-398834/

As far as the LEDs are concerned, the STC already has 2 lights that light up to indicate whether it is powering hot or cold mode.

It also has a power switch right on the control panel face.

To save the compressor you set the compressor delay to ~ 3+ minutes to allow the compressor to take a break between cycles and the temp differential to 2-3C if monitoring ambient air.

These are great little controllers. Good choice on your decision to get one.

[Kodos]

I know how to wire it for hot and cold, which is pretty simple. Basically just power going into the temp controller and then positive and negative going to either end of the duplex.

I may not understand your wording correctly, so please forgive me if I've interpreted it wrong, but the controller only works as a switch on the active wire for the hot and cold circuits.

ie for each of the heating and cooling circuits, you have an active wire going in, and an active wire going out (on to your heater/cooler) and the neutral wire connects directly to the neutral wire on its way into the unit.

The only neutral wire connected to the unit is the on that provides the unit itself with power.

If this is what you meant by "duplex" then that's cool, but I've seen electricians wire these up wrong (they ignored the wiring diagram) and if others read this thread, it would be a shame if they got the wrong idea.

As the previous poster (sorry, can't check the name in my mobile) said, it has LEDs to show which circuit is active, and has a compressor delay function built into the cooling programming (mine is set to 9minutes).

And what code said is the overriding rule for anything electrical, if in doubt call in a professional.

[Kodos]

Just looked at the link Steve Urquell offered, looks good to me (despite the strange US socket ;-D ).

It's vital that all cables are properly secured, you don't want an active wire getting loose and shorting out the whole system.

[codewritinfool]

Adding an additional relay would do nothing, it will be protected to the lowest amp rating...10 amps. It will blow the relay first, then your equipment anyway.

With all due respect, this is incorrect. If the STC-1000's contact closure is used to simply energize the coil on a higher-capacity relay, the largest load the STC-1000 contacts will see is the new relay coil... Probably a few milliamperes at worst. The new relay's contacts would bear the compressor load.

I can illustrate if necessary.

[maxwell]

Why would an additional relay reduce the wear on the compressor? The STC-1000 already has a short-cycle prevention feature, so it will not rapidly turn your compressor on and off. If you don't understand A/C power you should not attempt to wire the STC-1000. You could easily kill yourself or start a fire.