Fermwrap or flexwatt for heating

I am in the process of building a fermentation chamber using a 4.3cuin fridge..

Question is about heating and what to use...

Seems like either the flexwatt on the door or wall....

or

A FermWrap around the carboy...

I am not sure which I should go with. I have a fan mounted in the fridge so I will have good air circulation...

One question about using the FermWrap...do I still tape my temp probe on the side of the carboy?? I would assume I don't want it under the FermWrap being that would give a false reading to my controller right?

So, which one would you go with?

Wow a 4.3 cubic inch fridge? It must be adorable!

FermWrap is Flexwatt so the choices are the same. The fermwrap is just some Flexwatt with all the connectors and plug pre-installed. If you wrap your carboy with either one, you don't want to tape your temperature probe under or over it unless you devise some sort of heat-resistant insulation.

Considering you can only fit one carboy in the fridge, I'd recommend just mounting it to the fridge itself, on account of not having to do the procedure of wrapping the carboy when you put it in and unwrapping it when you take it out. This assumes you're not putting your fridge somewhere where it gets insanely cold though.

If you are mounting the heating element to the fridge itself, you could just use an aluminium clad resistor.

paint can with a light bulb in it

I grabbed some heat tape from ReptileBasics and wrapped my two carboys. Use a thermowell to get accurate internal temps. Works great.

I am in the process of building a fermentation chamber using a 4.3cuin fridge..

Click to expand...

Sorry...yea, that was pretty funny...ment to say 4.3cuft

If you are mounting the heating element to the fridge itself, you could just use an aluminium clad resistor.

Click to expand...

I have not read how to do this...can you give me some details??

Yes, my chamber is in my garage where it does get pretty cold. I was thinking about mounting the fermenting wrap on the door and maybe on the walls. How do I know how much I need?? My garage is about 55deg right now..

Also wanted to ask if the thermowell will work with the STC1000 probe...

meaning is the thermowell big enough to slide the probe down...

alien said:

If you are mounting the heating element to the fridge itself, you could just use an aluminium clad resistor.

Click to expand...

Let's say you want 20 W of heat. Get an old laptop power supply. Let's say it provides up to 3 A at 12 VDC. The first thing you need to calculate is how much current you will need at 12 V to supply 20 W of heat:

P = I * V (Power = current * voltage)

So to provide 20 W of heat you will need 20/12 = 1.66 A at 12 V. That is less than 3 A so the power supply can provide it. Next you need to know what value of resistor to choose.

V = I * R (Voltage drop = current * resistance)

You want a resistor that will drop 12 V when passing 1.66 A of current through it, so it will need to be 12 / 1.66 = 7.2 Ohms. Buy an aluminium clad resistor rated as close as possible to 7.2 Ohms that can handle at least 20 W. In this case, the closest you value you can easily get is 6.8 Ohms at 25 W. That's OK, but 6.8 Ohms at 50 W would give you more of a margin.

Now to get your 20 W of heat (actually 21.2 W) just connect your 6.8 Ohm resistor across the terminals of the 12 V power supply.

Don't hook up a resistor to directly to the mains electricity. Use a low voltage power supply.

You can also just get a ceramic reptile heating bulb and wire up a power tool cord to a lightbulb base. That's what I did and it is nice and compact and portable. I bought a 150W bulb from Amazon and it kept my 5 cu.ft chest freezer at 65ºF while my garage was mid 30s.

New_Climber said:

Also wanted to ask if the thermowell will work with the STC1000 probe...

meaning is the thermowell big enough to slide the probe down...

Click to expand...

I am using the 1/2" OD thermowell from StainlessBrewing.com WORKS GREAT!

Also, I am using the reptile basics 12" heat tape wrapped around my large malt drum fermentor... I have multi-temp control in my ferm chamber and right now, I am lagering one a beer at 37 and have an ale (Dus Alt) fermenting away at 60*F. The tape give a NICE GENTLE heat to the carboy.

See my signature for other details but here is a shot of the heat tape wrapped as well as the thermowell to accommodate the STC-1000 probe. I have since adjusted the heat tape wrap to be wrapped more straight and not spiraled. I noticed it was actually spiraled up above the wort level at 11 gallons.

I am using the 1/2" OD thermowell from StainlessBrewing.com WORKS GREAT!

Click to expand...

Do you have any issues with sanitation of the thermoweld? I would think you can take the cap at the end of the probe apart to clean it..but any other issues? I would be using this on a carboy, and already have the cap with 2 outlets...

Huaco said:

I am using the 1/2" OD thermowell from StainlessBrewing.com WORKS GREAT!

Also, I am using the reptile basics 12" heat tape wrapped around my large malt drum fermentor... I have multi-temp control in my ferm chamber and right now, I am lagering one a beer at 37 and have an ale (Dus Alt) fermenting away at 60*F. The tape give a NICE GENTLE heat to the carboy.

See my signature for other details but here is a shot of the heat tape wrapped as well as the thermowell to accommodate the STC-1000 probe. I have since adjusted the heat tape wrap to be wrapped more straight and not spiraled. I noticed it was actually spiraled up above the wort level at 11 gallons.

Click to expand...

I thought the spiral look was quite sexy actually. You should consult with me before making such drastic changes in the future

Me? I just use a little 500W space heater/love controller in my freezer. It's been-20 out there lately but 63 for the beer always!

New_Climber said:

Do you have any issues with sanitation of the thermoweld? I would think you can take the cap at the end of the probe apart to clean it..but any other issues? I would be using this on a carboy, and already have the cap with 2 outlets...

Click to expand...

Yeah, it can be taken off.

Since it is all stainless, I make sure it gets good and clean after it is used and then throw it in the boil kettle for the last few minutes. That will kill off anything that may be lurking around in the little crevices.

Good info! I place my 6.5gal plastic fermenters and 5gal Better Bottle Carboys into soft bag coolers ("Thermal Tote" -Pic attached) to help control temps. Would there be any issue/concern with using the TGH Heat Tape or a 'Ultratherm Heat Pad' (low watt) inside & likely touching the side of the bag? If not, what size would you recommend? FYI, we spend winters in southern AZ so doesn't generally get that cold here.

Since I also just completed a STC-1000 Temp Controller build, I though I would use it to control the heat?

Thanks for any help!
Robert
GypsyBrew

Not to bring an old thread up from the dead, but...well, yes to bring it up haha. I just bought 4 ft of the 12" flexwatt tape to put in my ferm chamber. I was hoping I could use it to heat my ferms up to 90-100F for finishing saisons and to sour wort. I installed it and I believe it's heating but not very well. The temps of a beer bottle with water in it haven't changed but 0.1 degree in about 2 hours. Do you think this material will be sufficient to bring temps up to the range I need them or should I find another way to do that? Just hate to waste the $26 I paid.

I have it wrapped around three of the walls inside the chamber, not around the individual fermenter. I'd prefer not to do the latter if possible, since it would be just another thing to manage putting on and taking off and would get frustrating I'm sure. Thoughts?

Disregard! Wire came loose during install. Fixed it and there is definitely some warmth to the touch now. Whew.

I still don't know if you'll see those temperatures - what is the wrap you ordered rated at? Most of the time these are designed to be in direct contact with whatever their heating - you put it under the glass in a terrarium(sp?) to heat the ground for the critters. In direct contact with a 6.5gal glass carboy, I've had no problem maintaining temperatures into the low 70s while the basement is in the high 40s. It may be able to go higher, but air is a great insulator so if you're just wrapping it on the inside of your ferm chamber I'm not sure how effective it would be, especially at those higher temperatures.

-Kevin

Hairdryer connected to a temp controller. Circulates the air and raises temperatures quickly and has the added bonus of gfci protection on the plug. I've used it to get temps in the mid 90s for saison so far but I'm sure it could go higher

BadNewsBrewery said:

I still don't know if you'll see those temperatures - what is the wrap you ordered rated at?

Click to expand...

If this question was directed at me, it's rated at 23W per foot, so at roughly 3.5 ft that equals math-are-hard. But it heated a beer bottle of water to 99 degrees once I fixed the wiring. It may have kept going but I turned it off at 99.