Would an 1800-watt hotplate be sufficient for boiling three to four gallons of wort? The time to do it is not vitally important; I’d do it when I know I have sufficient off-duty time to boil it and cool it down in a water bath. My concern is to avoid the costs and bullschumer associated with a propane burner and a 20-pound bottle of gas. Opinions welcomed!
Yes.
It might take it a while but it will maintain a boil. I have a 3500w that I bring 6 gal to a boil then power down to 1600w once the boil begins.
I have a cheap-ish 1800W induction cooker that works quite well for 3-gallon batches. You just have to make sure your kettle is compatible with induction heating.
Please provide manufacturer and model number info; I’d like to read about it. Would 110V household voltage run the thing? All I saw on amazon was maximum 1800-watt units. My kettle is eight gallons, by Brewer’s Best. Stainless steel. The bottom is not a thick, multi-ply affair. I will use an aluminum flame-tamer (11" dia. x 4mm thick) to spread the heat. I’ve used it once on my gas range and it really works! To boil inside, out of the sun and away from the winds blowing dirt into my kettle, would be fabulous.
3500 watts, 110 volts: Amazon.com
I saw several others on amazon that were also 3500 watts, but all required 220 - 240 volts. I do not have that kind of juice coming out of my outlets…
My kettle is not induction-compatible: A magnet will not stick to it. Looks like I’m stuck with doing my boils on my 7,000 BTU gas range. Bummer…
If you can drill a couple of holes in your kettle you may be able to add a heating element inside. The Blichmann 7 gallon Boil Coil will work on 120V with a 20 A breaker.
Of course if you want anything other than full power you will need some kind of controller.
Magnets don’t stick to my cheap Harbor Freight stainless kettles either but they still heat up on the induction plate 
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The magnet-sticking effect is a poor proxy for induction compatibility, although it often works. Magnets stick to materials based on their DC ferromagnetic properties. Induction kettles work on the basis of eddy currents induced by high-frequency magnetic fields. Any conductor will have currents induced by the transformer in the induction plate, but a good conductor like copper will not have enough resistance to heat up from the currents. Aluminum is similar. Magnets will not stick to either. Cast iron and most low-quality iron alloys are bad conductors and will heat up on an induction plate. Coincidentally, the iron content will make a magnet stick. Stainless steel is a mixed bag because there are so many different stainless alloys. Magnets will stick to some and not to others. Some will heat up on an induction plate, some will not. I am not surprised that there are cheap stainless kettles to which magnets don’t stick but which heat up on induction cooktops. The more expensive ones are more likely to use an alloy that will not work with induction cooktops, although we may see more manufacturers putting a layer of induction-compatible metal in all good cookware in the future as induction cooking becomes more widespread.
It may also be worth noting that the cheapest all-in-ones are now barely any more expensive than an induction plate and a stainless kettle.
I have a rather inexpensive and NON magnetic SS Hot Liquor Kettle on a commercial induction burner by Waring and it can easily boil 8 gallons of water. It is 1800 watts on a 120v circuit. It’s about 10 years old and running great!
[quote=“KellerBrauer, post:12, topic:32925, username:KellerBrauer”]
That unruly child is $355, plus 7.1% Nevada sales tax. Total is $380. Shipping ought to be free at that level of spending. I can buy 38 six-packs of craftbeer at $10/six-pack, or 31 six-packs at $12/six-pack for that kind of money. Gonna have to pass on the beauty you’ve got.
I saw a 1200-watt cast-iron burner plate that got to 1071 degrees at full-power; was tested using an infrared pyrometer. Would that much heat get six gallons to boil in less than a week?
[quote=“nvshooter2276, post:13, topic:32925, username:nvshooter2276”]
It might take close to an hour to get from mashing temperature to a boil. It depends on how much of that power is actually going into the liquid and how much is being lost to heating the air, etc. If everything is perfect and you get all 1200 watts into 6 gallons of liquid it would take 32 mins to go from 168F to 212F. If you only get 1000 watts into the liquid it will take 39 mins.
With me being just a trucker, you know much more about the calculations concerning how much time is required to get six gallons of water at room temperature (assume 72 degrees) to boiling at 204 degrees (at my altitude of 4150 feet ASL). I once timed the time-to-boil for three gallons at 52 degrees to boiling: 98 minutes. I used my aluminum flame-tamer, which I really do believe speeds boiling because it spreads the heat over the entire 95 square inches of the bottom of the kettle. I suppose I could set the water over the lowest flame at 2300 hrs, thus having it dam-ned hot or even gently boiling at 0800 hrs when I fall out of the rack. The top would be in place, so I’m guessing not too much evaporation. I drilled a 3/8-inch hole in the top to help avoid a boil-over. FermCaps-S is really good for that, too.
I’m just a simple extract brewer. I’ll never become an all-grain brewer; takes far too much time. Part of the application process to drive for FedEx Ground is to swear on any of Charlie Papazian’s books that homebrewing shall take a distant backseat to a load that has to roll to_day-- like right now!_ Looking back at my various records, I have not made any beer since April 2021. So disheartening…
I have read several times that the plastic used for translucent fermenters (like BrewDemon’s 2-gallon conical) cannot tolerate wort of more than 140 degrees. I wondered what is the melting point of HDPE, such as for the 5-gallon buckets we all know and love. It’s 248 degrees, so just-boiled wort can go straight from the kettle to the fermenter. I’m thinking the plastic will shed the heat faster than will the stainless steel, and we always have cold-water baths to get there sooner.
The only thing I would add is that HDPE becomes mailable at a much lower temperature. So, wort in the 200’s may deform the fermentor. Maybe that’s where the 140 degree limit comes into play?
The 130 or 140 F limit is for PET, the clear plastic fermenters made of the same material as soda bottles (but thicker). The HDPE used in buckets may melt at 248, but I agree that it might soften and deform well below that. I would cool down wort from the kettle as much as possible before putting it into a bucket.
As far as heating water from room temperature (is Nevada really only 72 these days?) to 204, that would take 98 - 117 mins, depending on whether 1000 W or 1200 Watts goes into the water. I did those calculations using a spreadsheet that has all the physics constants and uses asterisks for multiplication. 
Nevada, in the Reno area, was over 100 yesterday. Today, too. I stayed inside all day with my A/C blasting away at 73 degrees. Drove to Stockton, yesterday. It was 108 about fifteen miles from where I-80 crosses 99 South; around Roseville. That’s so hot, you just want to get inside to get the helsinki out of the blazin’ sun and suffocating heat.
I was just thinking out loud about just-boiled wort being poured directly into an HDPE bucket. Theoretically, it can be done. I hadn’t considered a possible deformation because of the temperature. I want to thank those who have blazed the trail for me in this regard. I’ll cool it down in water baths to about 100, then pour it into the bucket. I doubt my tap water will be able to get it to around 75 unless I change it several times. Water is kind o’ scarce in the desert, so we try not to waste it by filling a 22-gallon tote to the same level as is the hot wort in our kettles four or five times over. Too bad it’s not the dead of winter, right now. I’d set the kettle out on my balcony and let Mother Nature take care of cooling the wort…
I’ve had good success on my last 2 batches doing a partial boil and using extremely cold (purified/sanitized) water to top off the volume post-boil before transferring to the fermenter.
Yes, I have done the partial boil and top up with cold water. It means you have to start your prep a couple of days ahead of time to get your water sanitized and cold, but if you mix 2.5 gallons of 40 F water with 2.5 gallons of 100F wort you should end up with 5 gallons at 70 F.