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-   -   Fermwrap or flexwatt for heating (http://www.homebrewtalk.com/f51/fermwrap-flexwatt-heating-383553/)

New_Climber 01-22-2013 10:45 AM

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?

CapnBry 01-22-2013 02:51 PM

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.

alien 01-22-2013 04:19 PM

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

doctorRobert 01-22-2013 05:14 PM

paint can with a light bulb in it

BadNewsBrewery 01-22-2013 06:17 PM

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

New_Climber 01-23-2013 02:10 AM

Quote:

I am in the process of building a fermentation chamber using a 4.3cuin fridge..
Sorry...yea, that was pretty funny...ment to say 4.3cuft

Quote:

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

New_Climber 01-23-2013 02:12 AM

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 01-23-2013 06:36 AM

Quote:

Originally Posted by alien (Post 4813162)
If you are mounting the heating element to the fridge itself, you could just use an aluminium clad resistor.

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.

worxman02 01-23-2013 07:53 AM

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 65F while my garage was mid 30s.

Huaco 01-23-2013 01:28 PM

Quote:

Originally Posted by New_Climber (Post 4815388)
Also wanted to ask if the thermowell will work with the STC1000 probe...

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

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.
https://dl.dropbox.com/u/123996655/FermChamber%2024.jpg


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