Chiller / Heater with Johnson Controller w/pic

I wired my Johnson A19 to a split outlet so that I can plug in a lamp for heating mode or my freezer for chilling mode. I wouldn't recommend using both at the same time because it would unnecessarily force faster cycling of both. But this saves me from opening the A19 and rewiring it when the weather changes.

To split the outlet, you need to break the tab on the hot side of the outlet. I'll put up a schematic if anyone cares.



NOTE: there are many similar-looking models of this thermostat. I think a lot of the pre-wired ones from the brew shops are SPST (single-pole single-throw) relays; in that case, they WON'T work. You must have a STDT. check the following table to see if your's is on the list. I think the brew shops carry the A19-AAT, which is a SPST (won't work). That one for some reason isn't in this table.

I think I have a -ABC model, but not sure.



Here's the wiring diagram. Really simple. Just make sure to break the brass tab or both outlets will be on all the time.

I care, I'm interested how the wiring works.

Clever. Beats cracking the A19 open twice a year to flip from cool to heat.

jkarp said:

Clever. Beats cracking the A19 open twice a year to flip from cool to heat.

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Just wire a rocker switch to the internal terminals. That way you can switch from heat to cool from the switch that is mounted to the outside of the controller. This is what I did to mine. Works like a champ.

EmDubeu said:

Just wire a rocker switch to the internal terminals. That way you can switch from heat to cool from the switch that is mounted to the outside of the controller. This is what I did to mine. Works like a champ.

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That's a great idea, but you'd need a SPDT. Switches from Home Depot are all SPST (I think).

passedpawn said:

That's a great idea, but you'd need a SPDT. Switches from Home Depot are all SPST (I think).

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Yes, definitely doublethrow. That's what I used.

EmDubeu said:

Just wire a rocker switch to the internal terminals. That way you can switch from heat to cool from the switch that is mounted to the outside of the controller. This is what I did to mine. Works like a champ.

Click to expand...

Can you post pictures and instructions? I thought I would only need 'cool' but I'm realizing it's going to be a lot cooler this winter (in Florida) in my brew room than I originally thought. If not, I will probably copy the Original Post up top. Thanks!

NewBrewB said:

Can you post pictures and instructions? I thought I would only need 'cool' but I'm realizing it's going to be a lot cooler this winter (in Florida) in my brew room than I originally thought. If not, I will probably copy the Original Post up top. Thanks!

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If I were you I'd skip this and just use the STC1000 build threads here. It's a cheap solution, and far better than my kludge that I made before the STC thing was around. Do a search and you'll see, it's much better.

But I already bought a Johnson

NewBrewB said:

But I already bought a Johnson

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Epically quotable.

Cheers!

Nicely done. Execution Rating: 9.7 !!!