Minimum element wattage?

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cruizer8

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I am interested in moving to an electric brew kettle but I am having some trouble finding some info. Basically, I am trying to figure out the minimum wattage element I would need to boil about 7 gallons of water in my kettle from a 110V source. However, sometime in the future I plan to upgrade to a 220V system and would like to reuse the element so optimally I would get a 220V element and run it at 110V.

Thanks for any thoughts or info.
 
I’m a kitchen brewer, I use an electric stove. The big element is 5500W, the smaller is 4500W. The big one will boil two gallons of water in a three gallon pot in about 23 minutes, the little one, 28 minutes. Three gallons in a 4 gallon pot takes an hour or more, it just barely boils on the big burner.

About the voltage, for a given resistance, the power is the square of the voltage. Simply put, If you use a 240V element on 120V it will be at 25% of it’s rating.

The 110 thing is a pet peeve for me. I like to say if you have 110V service, call an electrician. US residential mains voltage is 120 (per leg) ± 5%. In my experience, measured RMS voltage is 120-123V. If you’re dropping 10 volts on house wiring, you could burn your house down.

I hope this helps, and gets you started. I'm sure somebody with with more direct experience with your situation will chime in.
 
5500 watts in an immersible element is a different animal from 5500 watts in a cooktop. An element of that size in my keggle will readily boil 8 gallons of water within 20 minutes or so, starting from room temperature. But, as noted above, it will be 1/4 of that power (1375 watts) on 120 volts.

I don't think you're going to be able to boil 7 gallons using a single household 120-volt circuit, and even using two circuits to run two heaters (1800 watts each, maxing out a 15-amp circuit) is likely to take a long time.
 
I have been experimenting with a 44 quart Bayou Kettle put inside an old 10 gallon cooler https://www.homebrewtalk.com/f11/my-new-mash-tun-268370/ with a 1500 watt 120 volt element installed. So far I have had good success simulating 7 gallons for a BIAB setup. Took a little over 1 hour to get up to strike temperature of 162. I let it sit to drop the temperature for a while and then brought it to a boil in 45 minutes. It was able to maintain a rolling boil with the PID set in manual at about 90% uncovered.

That lets me know that it is marginal but doable with a pump for recirculation during the mash on a single 20 amp circuit. All I need now is a bag to put inside the Bayou steamer basket to do a single vessel BIAB run. Now I'll be able to do 5 gallon batches in the kitchen during the winter.

As a plus, it is now used as an HLT for my RIMS system and has been used many times for sous vide cooking.
 
ChuckO, that’s brilliant. Interesting that even with an insulated kettle it takes 90% of 1500 watts to maintain a rolling boil.

Danb35 I’m sure putting the heat source in the kettle is more efficient, but something’s off here. 8 gallons is about 30 Liters. If we go from room temperature to boiling that’s 75 Celsius degrees. Multiply to get 2,271,000 calories or about 9,500,000 joules. Divide by 5500w and we get 1727 seconds or 28 minutes 47 seconds. If you can do that in twenty minutes that’s 140% efficiency, disregarding any heat loss.

A stovetop is supposed to be 60% according to the DOE. I’m getting 25% on my stove. I don’t know how much of that is heat loss and how much is lousy efficiency heating a cheap stainless pot.
 
i used 2 x 1500w elements in a keggle, i did 7 gallon boils without a problem... boils too a bit to achieve, but it got to a boil and was fine.
 
Thanks for the info. I was hoping to get away with the 5500W at 120V running at 1375W but it doesn't sound like that will cut it. With 2 1500W elements, would you have to run that on two separate 20A circuits? I want to make a 110 setup similar to www.theelectricbrewery.com but maybe I will see if there is another system style I could use.
 
Thanks for the info. I was hoping to get away with the 5500W at 120V running at 1375W but it doesn't sound like that will cut it. With 2 1500W elements, would you have to run that on two separate 20A circuits? I want to make a 110 setup similar to www.theelectricbrewery.com but maybe I will see if there is another system style I could use.

On the setup I described in the insulated kettle I first tried a 5500W at 120V and was able to achieve a boil with a lid on. As soon as I removed the lid the boil slowed down and finally stopped, but I had some slight cross ventilation to make things worse. Doesn't jibe with my 1500W running at 90% to hold a boil, but that's how it worked out.
 
Danb35 I’m sure putting the heat source in the kettle is more efficient, but something’s off here.
Apparently what was off was my memory. I brewed yesterday and kept notes on time/temperature. It took 20 minutes to take 8 gallons from 74 F to 155 F, and another 15 minutes to take 7 gallons from 155 F to boiling.
 
I have used both a 5500w element at 120v and a 2000w element. In my opinion the reduced time to boil wort is worth the cost of a new element once you can move to 240v. I just switched all my equipment back to the 2000w elements from 5500w elements until I can get a better brewing area setup.
 
IME a 2000w element will hold a boil for 5 gallon batches FWIW.

I will second that, If you don't mind waiting a little bit a single 2000W element is all you need for a 5 gallon batch. so long as you don't have a gigantic kettle with lots surface area to loose heat, it helps to insulate as well.

I have biab set up with one 2000 W element in a 11 gallon pot and it takes about 35 min to go from mash out to boil on 6.5 gallons if i put the lid on and wrap the kettle in a blanket.

-chickens
 
I will second that, If you don't mind waiting a little bit a single 2000W element is all you need for a 5 gallon batch. so long as you don't have a gigantic kettle with lots surface area to loose heat, it helps to insulate as well.

I have biab set up with one 2000 W element in a 11 gallon pot and it takes about 35 min to go from mash out to boil on 6.5 gallons if i put the lid on and wrap the kettle in a blanket.

-chickens

This +1
I run a 2000w 120v element and have no problem with boils. I do want to move to full boils "5.5gal" and feel it would do it no problem if insulated. Here is the element i use.

http://bostonheatingsupply.com/SP10868GL.aspx
 
This +1
I run a 2000w 120v element and have no problem with boils. I do want to move to full boils "5.5gal" and feel it would do it no problem if insulated. Here is the element i use.

http://bostonheatingsupply.com/SP10868GL.aspx

That is the same one I use. My single 2000 w element boiled 7 gal no problem this weekend. So that is a legitimate option for sure. Slower than running 2 elements at 120 or a 240 set up but also cheaper and more portable.
 

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