wiring diagram for two STC-1000 controlling two heaters and one fridge

[BrewskiBroski]

Hey guys - have searched all over for a wiring diagram to fit this question and i haven't found it. So here is the question:

I have a fermentation chamber that can hold 2+ carboys. I bought 2 STC-1000 to control 2 ferm heaters (1 for each carboy) but they are sharing a fridge. Will it cause an electrical issue if I use one outlet for the fridge controlled by both STC-1000, or is there an issue since it will be two power sources that would be supplying that outlet. That outlet would use a shared ground and shared hots.

 

[day_trippr]

Tying the two controllers together to run the compressor wouldn't break anything - it's a logical OR circuit. The question might be where to place the probes so they're reasonably in sync, otherwise one may be calling for cold while the other calls for heat, which will jack up your electric bill...

Cheers!

 

[reynolds5520]

If you use both to control cooling, the compressor delay function won't work properly since one controller doesn't know when the other last called for cooling.

 

[BrewskiBroski]

thanks for the replies and very valid points.... so even if both controllers are triggered for cooling, it wouldn't be power overload?

 

[day_trippr]

thanks for the replies and very valid points.... so even if both controllers are triggered for cooling, it wouldn't be power overload?

Nope. It's still just 110VAC.

But reynolds5520 brought up the best argument against the idea...

Cheers!

 

[reynolds5520]

Maybe you could use the factory thermostat to hold the fridge just below where you want your carboys to be. Then use the two controllers to control the carboy heating.

Or, use one controller for heat and cool of whichever carboy needs to be colder. The other for heat only on the warmer carboy.


Electrically there is no problem with the two different relays feeding power to the same compressor. It won't make a "power overload". Each is just a different switch to the same 120 VAC power source.

That said, you really don't want to override the compressor delay function that way. When the compressor cycles off there is still pressure on the high side that takes time to bleed through the evaporator. If the compressor cycles on again too soon, it won't be able to turn against that pressure. There is an over temperature safety device that breaks power to the compressor so it doesn't burn out. But that device isn't designed to cycle often, and the compressor motor has to get hot first before it does - not good for the compressor.