2 ac-ac SSRs in Parallel, Only one on at a time

Thread Starter

Uber_Goober

Joined Jan 19, 2013
45
I'm using a temperature controller to maintain the temperature in my wine cellar. It controls an air conditioner and a space heater and works fine.

I'd also like to turn on a fan when either the AC or Heater turn on.

I understand that SSRs aren't supposed to be used in parallel to increase current output. But can they be used in parallel when only one of them will ever be on at a time? I'm thinking to use 2 ac-ac SSRs with inputs connected directly to the AC and Heater power, and then or-wire the SSR outputs to power the fans.

I'm thinking this should work, but I thought I'd check in here. Is there a better/simpler way?

Thanks!
 

crutschow

Joined Mar 14, 2008
25,267
Normally the control input for the SSR is DC.
Are the control signals to the AC and Heater also DC?
If so then just use one SSR and diode-OR the two inputs (one diode in series with each input) to the fan SSR input.
That way either input will turn on the fan but the two inputs won't interfere with each other.
 

Thread Starter

Uber_Goober

Joined Jan 19, 2013
45
Normally the control input for the SSR is DC.
Are the control signals to the AC and Heater also DC?
If so then just use one SSR and diode-OR the two inputs (one diode in series with each input) to the fan SSR input.
That way either input will turn on the fan but the two inputs won't interfere with each other.
No- my controller uses relays putting out 115vac directly for the AC & Heater, so I have to go off that- hence the SSRs with AC inputs.
 
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