Brewer Heat pads

Hi all, Ive been using the plastic brewer heat pads that I purchased.  I use a big chest freezer that I keep at 40 degrees and control with one temp controller.  I insulate one side with foam and put the pads on the foam and my carboys on those and use a separate temp controller to control the heat pads to get my ferm temps.  I have been thinking(perhaps overthinking), that the heat pads are cooking the yeast on the bottom to a higher temp then whats reflected on the carboy since it heats from the bottom up, especially with bottom feeding yeasts like lagers.  Has anyone had any experience with these? Major off flavors etc?  Or is the temperature of the wort on top keeping things in check.

I haven’t used them, it’s hard to say what’s going on.  Can you measure the temp just above the foam?

You can always put the pad in the freezer and just let it warm the air.

But given that is a chest freezer, why are you using a heating pad?  Is ambient temp outside the freezer lower than 40?  Where is the temperature probe for the one controller you’re using, and is it connected to the freezer or the heating pad?

I tape mine to the side of the carboy with painter’s tape.

The freezer is enormous(can hold 9 cornys and 2 6 gal carboys).

The first temp controller is controlling the freezer itself set to 36-38 degrees. That probe is just dangling amidst the kegs.  The one side of the freezer is insulated off from the kegs. There is a separate temp controller that I use to control both heat pads.  I tape that controller to the side of the carboy, but it against the other carboy and put a little bit of bubblewrap insulation around the probe where it would be exposed to ambient air temp.  The controller controls both heat pads(I always brew similar beers together or the same beer and experiment with yeast or something so I dont hafta worry about one fermentation being much more active than the other, the carboys stay within 1 degree of each other).

I tape the probe about 4-6 inches above the bottom of the carboys.

so you have the freezer running while at the same time heating a portion of it? seems really energy inefficient! Your freezer is working harder to cool down the whole space (the cooling lines run throughout the sides) and the heating pad is working harder to heat the insulated space as the freezer is constantly cooling it.

How much above the freezer set point do you have the heating pad temp controller set to?  The higher it is the more the heat pads would have to be on.  I still think measuring the temp under the carboy while this is running would give you the info you’re looking for.  You can always just do it with a carboy of water to test it before you’re next batch.

It’s not the an optimal setup, so I assume you have reasons for rejecting other ways of maintaining fermentation temps?  A swamp cooler would probably get you what you want, but I don’t know all of your considerations.

The heat pads vary with the type of beer Im doing.  The overall freezer temp sits at about 40.  The heat pads are plastic and sit directly under the carboy, with the insulation in there the heat pads are actually operating about 5 minutes every 2 hours on average( a little more if im fermenting in the high 60s low 70s.  The insulation does a great job of keeping the cold air out of the small fermentation side, and with the one temp controller controlling the freezer being placed as far away from the insulated side as possible, it runs pretty efficiently(kicks on every couple hours with a 3 degree differential).  I’ve taken every precaution I can to assure that it runs efficiently as possible!  Also the pads dont suck much energy.  Space is one of my biggest considerations.  I have room for the one freezer and thats about it, and dont have much anywhere else in the house to maintain consistent temps.

I am going to try the carboy with water and put it on the very bottom and see where were at at the bottom as opposed to the fermometer in the middle of the carboy.

Hopefully a new house is coming soon with a garage and a bit more space!

you could buy one of my jacketed conicals i have for sale. then pump glycol through it and have the perfect fermentation temp.  todd

Jacketed conicals for sale? Huh? Do you have contact info? Price? Gallons? I’d be super interested in them.

Sorry check the classified section, if the ad is still up I have them.  I thought I could use them all but ran out of space in the laundry room. Todd

There’s a classified section on the AHA website? I can’t seem to find it.

okay here’s a picture. none of the single wall stuff, your beer will thank you for this…

The Classifieds are just another forum on this site…

http://www.homebrewersassociation.org/forum/index.php?board=26.0

Done some pretty extensive testing on these things.  It seems if you tape your temp probe about 4-6 inches up from the bottom of the carboy it maintains a pretty accurate temp throughout all of the liquid without scorching the bottom.  Sweet.

I assume that you can seal it off towars the end to carbonate, right?

What’s a bad boy like that cost?

The answer is sometimes yes and sometimes no.  I think it depends on the differential between the air temperature and the desired temperature of the beer.  If the air around your carboy is different by 10-15 F, then that heat pad will be working at its maximum to keep the carboy at the set temperature.  Additionally, if most of the surface area of the carboy is interacting with 40F, then the heating pad will also be working harder to keep up as it can only conduct heat through a very small amount of surface area.  In your case, yes, I think the carboy will be very warm on the bottom.  I had one batch where the probe was left just sitting out next to the carboy at room temperature.  The heating pad tried its very best to warm the ambient temperature of the room to the set point of the controller.  The bottom of the fermenter was darn near blood warm.

The easiest thing for you might be to put a thermo-strip as close to the bottom of your fermenter as you can and check it often.  Also, you should be able to use electrical tape and wrap the thermal mat around the fermenter to increase the amount of surface area being acted upon by heat and reducing the amount being acted on by the 40F air temperature of the freezer.