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06-21-2008, 10:54 PM   #1
The Pol
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 120v/2000 watt element, how long to heat water??

I am contemplating converting my HLT to a combination HLT/HERMS with a copper coil, water heater element, stirrer and a JC controller. Now here is what I need to know. In a 10 gallon cooler, how long will it take to heat up 9 gallons of water to say 180F? Is there even a way to calculate this? If it takes hours... well, Id hate that. Id assume in a small cooler with insulation that it could heat pretty quickly. HELP, anyone?

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06-22-2008, 01:28 AM   #2
GuateBrewer
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It takes one BTU of energy to raise one pound of water, one degree F. Water is 8.3 lb/gal so 9 gallons = 75 lbs. To continue to keep the numbers back of the envelope, say your water is 80deg and you want to goto 180, then you need 7500 BTU's of energy. The typical 35k-40k BTU/hr burner gets the job done pretty quick, but we only have 2kw/hr of energy.

1 kw/hr = 3413 BTUs so 7500/(3413*2) = 1.1 hrs...

This assumes 100% of your energy goes to heating the water and none of it is lost.

You can figure out how fast you want to heat your water, then take that kilowatt figure and divide by 120 or 240 to see how many amps you need. 2000 watts is 18 amps and pushing the limit of a typical household 120v plug. Most of the time they are rated for only 15 amps..

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06-22-2008, 01:51 AM   #3
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WOW, awesome... 1.1 hours is not HORRIBLE, but it isnt great either. I will have to think about this. It would be nice, electricity is easy to switch and route, alot easier than gas.

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06-22-2008, 05:23 AM   #4
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My thinking is to remove the kegs mounting base skirt then adding a 6" seciton off another keg to allow for a seperate section filled with anti-freeze with two 35, 45 or 5,500 watt heating elements. This system will need a expansion tube plus able to switch to one element PID controlled once up to temp. This with 230 volt power to make heat vs screwing around with 120 volt powered 230 volt elements directly mounted in the wort. I would rather heat 252 sq/in plus area than a element scorching the bier. Thinking stage so far. JMO's.

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06-22-2008, 12:14 PM   #5
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Yeah, I am still boiling with gas... and I have thought about a modified cornie as a heat exchanger, since I could fill it with say 3 gallons of water and it would heat alot quicker.

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06-22-2008, 07:13 PM   #6
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Looks like I am leaning toward a 2 gallon beverage cooler with a 1500 watt element, copper coil and a vent fan motor for an agitator. I will measure the temp of the wort at the HERMS outlet and have that control the coil. I will also set up a thermometer on the outlet of the MLT just to monitor the outlet temp so that I can tell when my mash has reached its proper temp. This is all subject to change, but thanks to Craigs List, I just came into some cash... heh.

If I did my math correctly... if I have 1.5 gallons in my dedicated heat exchanger, with a 1500W element, I can get it from 70 degrees to 160F in about 15 minutes. THEN, when I wish to ramp up to mashout temps, from say 150-170F... it will only take about 3 minutes. Now I have to recirculate all of the mash water once before the mash temp will be changed.... so mashout should only take 3 minutes for the HERMS to heat up, then at one gallon/min. (MAX) about 5 minutes to recircualte the mash water. TOTAL is 8 minutes.

All of my vessels are coolers, they hold temp pretty well, but this will give me repeatability and precise control of the mash temps. it will also allow me to mashout in a cooler. Using the 1500W element should allow me to use a standard 120v oulet in my garage, but coupled with the small volume of the HERMS, it should be a good match. Hows this sound?

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Last edited by The Pol; 06-22-2008 at 07:31 PM.

06-23-2008, 01:52 PM   #7
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06-23-2008, 04:58 PM   #8
eccsynd
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Here's a great spreadsheet to calculate heating times. Check out the 'Electric Heat Calculator' at the bottom of the page
http://suburb.semo.net/jet1024/BeerHome.htm

With a 1500W element, you're looking at anywhere from 2-3 deg/min, depending on volume, which is pretty respectable. Be careful, I think you're 15 min is correct to heat the 1.5g exchanger, but that's assuming the process water is already up to temp. It will take much longer to heat the ~4g of strike water to 160 from 70, about 51min (assuming 95% eff) for (4+1.5)=5.5gal.

If you have poor conduction between the HE water and the process water, the HE will become much hotter, and you'll get some overshoots. But this is something that a really good PID controller can easily adapt to. Yet another reason to minimize the HE water volume.

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06-23-2008, 09:40 PM   #9
The Pol
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I am not heating my strike water with electric... I am heating that with my burner, this is ONLY an electric HERMS, not a fully electric brew stand. I want to use electric for the HERMS only. The HERMS will only maintain my mash temp, and mash-out from 160-170F It is really impractical to use it for anything else when you are considering 1500W and a 15A draw. This is why I went from an electric HLT to an electric (small volume) heat exchanger. I THINK

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Last edited by The Pol; 06-23-2008 at 09:51 PM.

06-25-2008, 03:01 AM   #10
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Finally did a practical test today... 120v/1500W element with 9 gallons of water starting at 70F. It took just under 90 minutes to heat the water to 170F. This is about 97% efficiency in my Rubbermaid beverage cooler... so I am pretty happy with it.
Bought the element, PVC coupler and a pigtail that can handle the 15A draw of the element at Lowes for under \$15. Now of course I have to add an electric agitator, copper coil, thermowell and a temp controller... BUT, luckily I have the \$\$ now to do it, I just need the time to get it all converted so that I can brew on it again soon. Thanks for the websites and the helpful information here!

Looks like I AM going to heat my strike water with this electric HLT, will just fire it up while I am making breakfast, by the time I am finished with my coffee I will be ready to dough in and start my recirculation. (I will be keeping a gallon of cool water aside to help cut my HLT temp from 170F to about 157F after I dough in)

When heating my strike water I am getting about 1F per minute increase, when I am using the MLT as the HERMS I will be getting about 2F per minute with the reduced water volume.

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Last edited by The Pol; 06-25-2008 at 03:06 AM.