Fermwrap and Johnson Controls A419

Hi there experts of HBT, I have a question. Or 3, let's see how this goes.

So I wanted to control the temperatures of my fermentation more precisely, and did a ton of research on this forum and elsewhere, and I decided on this system.

I decided to get a fermwrap type fermentation heater and Johnson Controls A419 temp controller from Northern Brewer. In an effort to make sure this system would work for keeping my upcoming (tomorrow) all grain pale ale fermenting at an even 65 degrees, I decided to do a little experiment.

For the control I set up a carboy with 72 degree water in my basement overnight last night to see what my temperature would be if I let it ferment down there, its a finished heated basement and I found that the water was around 75 this morning. So tonight I want to hook up the fermwrap and controller and put it in my 40 degree garage to see if it will maintain 65 degrees.

I set up the probe against the side of the carboy with bubble wrap as insulation and plugged the heater into the controller. I discovered a -4 degree difference from the controller probe and the thermometer, so I'd imagine to get 65 I'd set the set point to 61 degrees?

Also, I guess I have to set the jumpers inside the unit for heating, and have the unit set for cut out? Cause I'd imagine the heater would be on until the temp hit 65, and then turn off, right? And then when the temp drops to the differential point the heater will kick back on? It's hard for me to decipher the technical directions that came with the unit, and everything I've seen only discusses using the unit with a chest freezer or fridge. I do want to do that in the future, but does anybody have experience using the fermwrap method?

Any advice would be greatly appreciated.

eeverwine said:

[...]Also, I guess I have to set the jumpers inside the unit for heating, and have the unit set for cut out? Cause I'd imagine the heater would be on until the temp hit 65, and then turn off, right? And then when the temp drops to the differential point the heater will kick back on?[...]

Click to expand...

You deciphered that exactly right: you want heating/cut-out mode...

Cheers!

Thank you sir, I thought I had that right. I'm also wondering about the differential, do I set it lower than my set point? If so, by how much?

eeverwine said:

Thank you sir, I thought I had that right. I'm also wondering about the differential, do I set it lower than my set point? If so, by how much?

Click to expand...

In heating/cut-off mode, the differential will be entirely below the set point. You just have to pick a value for how much lower than the set point you want to allow the brew to fall.

I'd opt for a small value, like 2 or 3 degrees, and make sure the probe is as tightly coupled to the fermentation vessel as possible, and insulated from outside influences. Strapping the probe to the side with a chunk of insulation foam, or even a couple of layers of bubble wrap) on the outside of it will work fairly well....

Cheers!

Awesome. I have the probe insulated like crazy with bubble wrap and electrical tape. It's reading a constant 4 degrees less than the water temperature.

Sorry for all the questions, but additionally, should I insulate the outside of the fermwrap somehow?

Thanks for the help. I'm gonna let it go overnight in the garage as is and in the morning if all goes according to plan my water will be 65F. I hope so, cause I'm brewing at 10am

I would be very careful about covering the ferm wrap in any insulation without checking the user instructions first to be sure there's no risk of overheating the belt or controls. Home brew isn't worth burning down the house...

Cheers!

Didn't insulate the fermwrap. Controller is working perfectly, my APA is fermenting at a perfect 65 degrees and holding steady. Thanks for the help

I've read about people wrapping their temp probes in bubble wrap. I am not saying that anyone is wrong in doing so, but my wort is always the temperature that my A419 is sensing.

EvilBrewing said:

I've read about people wrapping their temp probes in bubble wrap. I am not saying that anyone is wrong in doing so, but my wort is always the temperature that my A419 is sensing.

Click to expand...

They aren't entirely wrapping the probe with bubble wrap, they are taping the probe directly to the carboy, and then placing bubble wrap over the probe to insulate it from the surrounding air. This way the probe is measuring the temp of the carboy/wort and not the air in the room.

AAAHH! Okay. I don't need to do this as I use stainless carboys in a freezer whose temperature is maintained by A419

wow! a dream come true! Thanks for this post. I am having problems with the same issue. I appreciate this thread since it directly applies to my current problem. Weird though. NB told me to set it to cool/cut in. I think that is why it won't work this time. My garage gets cold in the winter as well. My unit shows 59 degree temp of the carboy, with a 68 cutout (set) temp. The relay won't come on to heat the fermawrap. I will try the heat cutout and see what that does. I have to get the temp stable before pitching the yeast.

I use this same setup in my sub-50 degree basement, and it works great.

I put the fermwrap and fermenter inside the minifridge I use as a fermentation chiller in the warm months. When the fridge is not on, it's just an insulated box, so it does a really nice job of keeping the heat from the fermwrap where it should be.

I built a box out of thin wood that is lined with styrofoam board. There is about 4 inches of clearance all round the carboy. Used in conjunction with the ferm wrap heater and Johnson temp controller, I have had great success in controlling my fermentation temps without worrying about burning my place down.

I just brewed a beer that required fermentation to be held at 68. I used the bubble wrap (tiny bubbles) with no trouble. My fermwrap is 12" reptile heat tape I bought for $3 a ft, 2 1/2 feet works nice and a wiring kit (cord, grommets and terminals) for $4 to control it I used a temperature controller similar to the STC-1000 I got for $14. and it worked like a charm. Next I want to make a thermotwell from a 3/8 racking tube for $7 and solder the end closed. Once I have the set up I'll make what I need for my primaries.