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-   -   Johnson A419 (http://www.homebrewtalk.com/f51/johnson-a419-310734/)

ssiimmoonn 03-06-2012 05:16 PM

Johnson A419
 
Know there's a ton of threads on this. But I am just trying to keep keg at normal drinking temp. Along with a couple of bottles . Chest freezer is now crowded at all and it's still in stock condition. What settings should I use for basic "fridge" temps. Thanks

DSmith 03-06-2012 05:28 PM

For Cut-Out at Setpoint, Cooling Mode
Setpoint at 38F or greater (desired minimum serving temp)
Anti short cycle = 12 min
Differential = 4F to 6F
Offset = 0F

For Cut-In at Setpoint, Cooling Mode
Setpoint at 44F or greater (desired maximum serving temp)
Anti short cycle = 12 min
Differential = 4F to 6F (confirm that Setpoint - Differential is >34F so you don't freeze your beer by accident; I intentially added margin to 32F)
Offset = 0F

Let the probe dangle in the freezer airspace. You may want to run a 12V PC fan in the freezer to circulate air.

You can also insulate over the probe on the outside of a full beer bottle and lower your differential to 2F.

OatStraw 03-06-2012 06:16 PM

I have been using this on my keezer for a couple days now. How do I know if it's operating at Cut-Out or Cut-In. I don't see this distinguished in the menu.

DSmith 03-06-2012 06:32 PM

Cut-In vs. Cut-Out mode can only be changed by opening the unit up and moving a black jumper inside. There are directions in the manual and I think printed inside the unit. You can choose one position and leave it that way.

I prefer "Cut-Out" at set-point. When you enter a set-point for cooling, you know the freezer will shut off when your set temperature is reached (you're setting the coldest temperature and allowing the freezer to drift up a degree or two). When you enter a set-point for heating, you know the heater will shut off when your set temperature is reached (you're setting the hottest temperature and allowing the freezer to drift down a degree or two). Either mode is fine and very similar when the Differential is set to 1F (which I do when insulating the probe onto a carboy). It takes a long time for 5 gallons of water to change temperature from the freezer's heat loss/absorption from the ambient.

I'm installing a switch to change from cooling/heating to not open up the unit anymore. The unit will need to be shutoff when flipping that switch because that's the way the jumpers work and I don't want to risk ruining it.

ssiimmoonn 03-06-2012 10:52 PM

awesome thanks, and do you know what the factory default is when i got this? for cut in or cut out?

DSmith 03-07-2012 01:45 AM

Quote:

Originally Posted by ssiimmoonn (Post 3865310)
awesome thanks, and do you know what the factory default is when i got this? for cut in or cut out?

Manual says default is Cooling Mode, Cut-In at setpoint. It's easy to open the unit up and check the jumpers against the diagram on the inside of the box or manual. Cut-Out at setpoint makes more sense to me based on my post above.

OatStraw 03-07-2012 11:59 PM

So I have mine set at 40* and the Diff set to 2*, but I will see it turn off at 38 yet a couple minutes later it reads 35*. I have the probe just hanging in the freezer. Is there that much of a delay that the temperature actual cools an additional 3* before it registers?

Also opened up the A419 to set to Cut-Out mode but there is only 2 Jumpers in there. 1 is on the Touchpad lock, and the other is on Jump 1. Based on the diagram in the manual I need 2 jumpers to make it operate in Cut-Out mode. Did you have to provide your own jumper?

DSmith 03-08-2012 12:37 PM

Quote:

Originally Posted by OatStraw (Post 3869539)
So I have mine set at 40* and the Diff set to 2*, but I will see it turn off at 38 yet a couple minutes later it reads 35*. I have the probe just hanging in the freezer. Is there that much of a delay that the temperature actual cools an additional 3* before it registers?

Also opened up the A419 to set to Cut-Out mode but there is only 2 Jumpers in there. 1 is on the Touchpad lock, and the other is on Jump 1. Based on the diagram in the manual I need 2 jumpers to make it operate in Cut-Out mode. Did you have to provide your own jumper?

The air temperature will go less than the setpoint because the cooling coils are still colder than 38F when the controller shuts the freezer off. The contents of the freezer will pull the air temperature back up pretty quickly. There is no delay in the temperature probe. This is the reason to use a big Differential when the probe is in the air. You can also insulate over the the probe on the side of a bottle/keg/carboy and the temperature will not go more then 1F then what you expect and you can use a smaller Differential without over cycling the freezer.

Are you circulating the air inside the freezer with a fan (12V computer fan)? If not, that may help keep the temperature more uniform.

Mine came with all 3 jumpers. You're ok with 2 as long as you understand how the Differential will be applied to the Setpoint. You can probably email Johnson Controller customer service and get a free replacement jumper.

OatStraw 03-08-2012 02:08 PM

Thanks DSmith, I will shoot them an email, or just pull a jumper out of an unused computer I have. How are you powering your fan? I am hesitant to drill any holes in the side of the Keezer to get power inside. I just have the probe cable going under the lid seal.

DSmith 03-08-2012 03:06 PM

I'm powering a fan with a cell phone charger (6 Volt) power supply that I cut and soldered to the fan wires. 12V makes the fan spin really fast and I had old cell phone chargers around. Goodwill/thrift shops have lots of DC power supplies for $1-$2. I extended the wire to the fan with some scrap 22g (twisted pair audio wire) and run it along with the the probe wire the same way you're doing it. The fan is zip tied to a wire rack inside the freezer.


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