### Author Topic: Using Johnson Dig. Controller with FermWrap Heater?  (Read 1382 times)

#### ukolowiczd

• Assistant Brewer
• Posts: 144
• Burlington, VT
##### Using Johnson Dig. Controller with FermWrap Heater?
« on: April 27, 2012, 06:28:53 AM »
I wrapped two saisons with FermWrap heaters and plugged them into the Johnson Dig. Controller only to realize that I'm not an electrician and could not understand the directions. Any help would be great as I can only find how to use these things in a refrigerator and they are NOT in a fridge as I want to heat them eventually to 80F.

I managed to move the little plastic thingy inside to close the connection for "heating" and changed the differential to 1 degree, but I still don't get the "Cut in" and "Cut out". I want it to read let's say 75F with a differential of 1 thus 74-76F. Currently I have it on "Cut in" but I don't understand why nor why I would change it to "Cut out". Any one have experience with this?

#### ukolowiczd

• Assistant Brewer
• Posts: 144
• Burlington, VT
##### Re: Using Johnson Dig. Controller with FermWrap Heater?Anyone? Bueller?
« Reply #1 on: April 27, 2012, 12:17:16 PM »
No one has experience with this? Help me Obi-wan; you're my only hope...

#### brushvalleybrewer

• Assistant Brewer
• Posts: 135
• Centre Hall, PA
##### Re: Using Johnson Dig. Controller with FermWrap Heater?
« Reply #2 on: April 28, 2012, 05:03:07 AM »
Hey ukolowiczd,

I use the same setup in my cellar. Here's what I do.

The Johnson is in heating mode. The set point is the “cut out” temperature, and the differential is set to 2 °F. This means, since the cellar is cold, that the temperature of the beer falls until it is 2 °F below the set point. Then the thermostat turns the heater on until it reaches the set point. That means that the beer will ferment at 66 ± 1 °F if I set the controller for 67 °F.

Does that help?
In a humble log cabin off an unregarded back road, somewhere, deep in the heart of Pennsylvania’s hill country, we find our intrepid hero — the Brush Valley Brewer.

#### ukolowiczd

• Assistant Brewer
• Posts: 144
• Burlington, VT
##### Re: Using Johnson Dig. Controller with FermWrap Heater?
« Reply #3 on: April 28, 2012, 06:56:36 AM »
Hey ukolowiczd,

I use the same setup in my cellar. Here's what I do.

The Johnson is in heating mode. The set point is the “cut out” temperature, and the differential is set to 2 °F. This means, since the cellar is cold, that the temperature of the beer falls until it is 2 °F below the set point. Then the thermostat turns the heater on until it reaches the set point. That means that the beer will ferment at 66 ± 1 °F if I set the controller for 67 °F.

Does that help?

Yes. So this means I should change it from cut in to cut out? What is it doing when it's in cut in?

#### brushvalleybrewer

• Assistant Brewer
• Posts: 135
• Centre Hall, PA
##### Re: Using Johnson Dig. Controller with FermWrap Heater?
« Reply #4 on: April 28, 2012, 03:41:59 PM »
So this means I should change it from cut in to cut out? What is it doing when it's in cut in?

You don't have to. All the modes work. Cut in and cut out refer to when the thermostat turns the circuit (and hence your fermwrap) on or off, and the combination of that and heating or cooling mode, the differential, and the temperature you set, define what happens.

Let's make it simple by focusing on your situation.

You're using a FermWrap, which is a heater, so I assume your environment is cold — either a basement or a fridge — and you want to heat your beer to be close to the desired temperature, so you want to use the controller in heating mode as you've said you have it.

You also said you've got yours set to "cut in."

What that means is that the thermostat will cut in — turn on the heater in this case — when it reaches the temperature you've set. When it cuts in, it is going to start heating and then the controller will cut out at the set temperature plus the differential. So in your example of wanting to get 74-76 degrees, and your controller in cut in mode and heating mode, you would set the thermostat for 74 degrees and the differential for 2 degrees. That way, if the temperature fell below 74 degrees (the set temperature), the heater would "cut in" and heat the wort until it rose 2 degrees (the differential) and would cut back out at 76 degrees.

I guess what I'm saying is you're fine how you are. If you're in heating mode and cut in mode, set the temperature to the lowest acceptable temperature and set the differential so that the set temperature plus the differential is your highest acceptable temperature.

I hope this helps.
« Last Edit: April 28, 2012, 03:43:54 PM by brushvalleybrewer »
In a humble log cabin off an unregarded back road, somewhere, deep in the heart of Pennsylvania’s hill country, we find our intrepid hero — the Brush Valley Brewer.

#### ukolowiczd

• Assistant Brewer
• Posts: 144
• Burlington, VT
##### Re: Using Johnson Dig. Controller with FermWrap Heater?
« Reply #5 on: April 29, 2012, 06:21:05 AM »
So this means I should change it from cut in to cut out? What is it doing when it's in cut in?

You don't have to. All the modes work. Cut in and cut out refer to when the thermostat turns the circuit (and hence your fermwrap) on or off, and the combination of that and heating or cooling mode, the differential, and the temperature you set, define what happens.

Let's make it simple by focusing on your situation.

You're using a FermWrap, which is a heater, so I assume your environment is cold — either a basement or a fridge — and you want to heat your beer to be close to the desired temperature, so you want to use the controller in heating mode as you've said you have it.

You also said you've got yours set to "cut in."

What that means is that the thermostat will cut in — turn on the heater in this case — when it reaches the temperature you've set. When it cuts in, it is going to start heating and then the controller will cut out at the set temperature plus the differential. So in your example of wanting to get 74-76 degrees, and your controller in cut in mode and heating mode, you would set the thermostat for 74 degrees and the differential for 2 degrees. That way, if the temperature fell below 74 degrees (the set temperature), the heater would "cut in" and heat the wort until it rose 2 degrees (the differential) and would cut back out at 76 degrees.

I guess what I'm saying is you're fine how you are. If you're in heating mode and cut in mode, set the temperature to the lowest acceptable temperature and set the differential so that the set temperature plus the differential is your highest acceptable temperature.

I hope this helps.

That makes total sense. It's been working great. Using it to bring up a saison temp into the 80's in the house so it doesn't have far to go. Thanks!