I think I got the wrong johnson controller

[doctorRobert]

So I'm turning my mini fridge to a fermentation chamber. Cooling via the fridge, paint can lamp heater as a heat source.

I got the Johnson Controls A28AA-37C 2-Stage Temperature Controller, and when I wired it, what happened is that the fridge and light turn on at the same time. There is a range, where only the light turns on, but basically, I think I have the wrong controller. For example this is what happens now

Lets say ambient temp is 70.
If I set the thermostat to 68, the light bulb turn on.
If I set the thermostat to 65, both the fridge and light bulb turns on.

So it is two stage, just not the correct type. Is there anyway to change it or do I need a new one.

 

[mikescooling]

Hi, I'm in HVAC. You have a SPDT switch when you want a SPST switch. You can ether look at how the power out is hooked up or buy the SPST controler. Your a smart guy and I don't have to say, only trained people should kill them sleves Bla...bla..bla

 

[rekoob]

not sure about that controller but can you change each stage from "H" (heat) to "C" (cool)?

 

[doctorRobert]

Thanks. think I'm going to go with the Ebay acquarium controller build. And use this to control my keezer, as this should work at that - and then sell that controller on ebay.

 

[doctorRobert]

not sure about that controller but can you change each stage from "H" (heat) to "C" (cool)?

Haven't seen anything in the manual about that. I'd imagine that's not possible.

 

[chrisdaman77]

I would try (can't hurt) setting the difference between your hot and cold more than just 3 degrees apart. Try something more like 5 and see what happens. From what I am reading there is a 2-7 adj between stages. I am not sure if this will help but it is worth a shot. As for the ebay ones I have 2 of them and I love them. Just need a conversion chart or like I did I have a converter right on my phone. One thing to think about is where the fridge is located. If it is in a fairly warm area then it will only kick the fridge on when it is too hot. If you have it in a fairly cold area then just worry about adding heat. Just a thought at least that is what I am doing but then again mine will always be in a 70-75 degree area so only need to cool it down.

 

[ClaudiusB]

I would try (can't hurt) setting the difference between your hot and cold more than just 3 degrees apart. Try something more like 5 and see what happens. From what I am reading there is a 2-7 adj between stages. I am not sure if this will help but it is worth a shot. As for the .

You are correct adjusting the differential between the two stages should do it.

Cheers,
ClaudiusB

 

[chrisdaman77]

Wondering how you made out. Did it work by setting your temps farther apart?

 

[doctorRobert]

No. Didn't try. Conceptually it could possibly work, by having the heater and fridge both on, and the heat will outpace the fridge. But that wont be efficient. I'm going ebay acquarium route instead.