Heat tape for heating kettles?

[SeligmansDog]

I may not be in the right forum, but I was wondering if anyone ever tried a wrapped tape for heating a brewpot? I was imagining a few wraps of a 3" thermo-controlled heat tape (like this http://www.mcmaster.com/#heat-cable/=ly2o0s). I think it'd be next best thing to a jacketed reactor.

 

[Bobby_M]

I've considered it for holding mash temps but you're not going to be able to get enough wattage on a boil kettle at least not without a big wallet beatdown. Typical heat tapes run about 20-50 watts per foot so even in best case, you need 40 feet of cable for 2000watts so that's a few $100 and barely enough to boil.

 

[BadNewsBrewery]

Not to mention the heat tape doesn't have the greatest heat transfer coefficient because it's wrapped around the exterior of the kettle vs. shoved right in the inside like a heatstick or element. If you installed a boatload of heat tape, and then insullated the bejesus out of the kettle, you might see some benefit from it, but as Bobby said - you need a lot of tape, and I'd be concerned about damaging the tape once you started getting up to multiple layers and the heat it would produce.

Most of the heat tape you linked to is there to keep pipes from freezing, and only needs to provide a marginal amount of heat to the pipe to keep the pipe above 32*. To get 5-15gal of water/wort up to any usable temperature would be damn difficult and even more expensive.

 

[SeligmansDog]

@Bobby, thanks, my understanding of the energy requirements of heating gallons was pretty far off, I appreciate the answer.

@BadNews The description says it can't be layered or it'll burn out. Also, this isn't just keep your pipes from freezing tape, it's for applications of -30 - 450F, I think it's durable stuff. It also appealed to me because it wasn't a heat stick that could burn any particle nearby, a more diffuse heat applied to the exterior. A 3" wide 8' section (a good few wraps around a kettle) would provide 1440 watts for $230, but apparently that's still not enough for a boil.

Thanks for the replies.

 

[BadNewsBrewery]

Good to know the tape is rated for that high of a temperature, definitely eliminates one concern. So based on a 15" diameter kettle, an 8' strip of heat tape will get you 2 wraps. Your ability to boil off 1440 watts isn't totally out the window by any means. It all depends on how much water you're trying to bring to boil and how well insulated your kettle is. If you can insulate the kettle well enough and put most of that 1440 into heating the water vs. heating the room, you're not going to be off to the races but you'll see temperature changes.

Curiously, why do you want to go this way? Large scale facilities use steam jacketed kettles because it's the quickest and cheapest way to produce large scale heating. Heating a 1500gal kettle over a propane stove or with a bunch of electric elements is not too practical. Get a boiler and heat up some water to high temp steam and send that around a kettle and you have a very efficient large scale heating process. Small scale and you lose those benefits and economies.

 

[SeligmansDog]

Interesting. My pot is stainless, 50 L and about 12" diameter. My interest in a more diffuse type of heat is that I'm heating a mash of suspended grains (like in distilling for stripping alcohol for fuel, wink). Heating a suspension of grain isn't too bad over a burner, I don't burn it, but I have to cook it slow or I will burn. I also brew beer and wondered about that application too.

Oh, to answer your question, I would be shooting to boil 5-8 gallons, 1/2 to 2/3 the height of the kettle. Insulation sounds impossible too without squashing the tape onto the surface, I think it's looking worse and worse.

Maybe I'll try to configure a copper insert against the inside walls and make a steam generator with a pressure cooker - that's another thread...