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My apartment has 120V outlets and my landlord probably won't install a 240v outlet.

This article on induction heating states that a 120v delivers a maximum of 2000 watts.

Almost all of the induction cooktops on Amazon are 1800 watts.

What is the largest size batch I can boil with a 120v outlet on an induction outlet? I would like to purchase a 15gallon kettle for 10 gallon batches, but this might be a deal breaker.

(edit - I have not all-grain brewed before, but my understanding is that for a 5 gallon batch, 6.5 gallons of wort are required due to evaporation and trub. Therefore, what is the largest amount of wort that can be boiled with an induction cooktop on a 120v outlet?)

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  • In addition to a 15-gallon kettle, it sounds like you're also shopping for cooktops. Why not shop for a turkey fryer instead, and take the whole mess outside?
    – djs
    Oct 29, 2014 at 6:10
  • @djs I'm apartment brewing unfortunately. Would a turkey fryer work inside?
    – Matthew Moisen
    Oct 30, 2014 at 0:10
  • 1
    definitely DO NOT use a turkey fryer inside. there is a serious carbon monoxide risk!
    – djs
    Oct 30, 2014 at 17:49

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Your 120V outlet is likely on a 15-amp circuit, giving you only 1800 watts of power. The good news is that induction systems direct most of the heat where it can do good.

1 watt (per hour) is 3,600 joules.

Wort has a specific heat of approximately 3.97 J/(g°C).

It takes 7,952,382.36 Joules to heat 6.5 gallons (24,700 ml or 24,700 g) water from 18°C to 100°C (= 3.97 * 78 * 24,700). Or 2,209 watts per hour. In other words, it would take 1.23 hours (1:15 hours) on that 1,800 watt induction burner to bring room temp water to just below boiling. This doesn't account for any loss of heat due to radiation of heat. And it assumes 100% efficiency, which is unrealistic.

The enthalpy of vaporization of water is 2,260 J/g, or 0.63 watts (per hour). Because not all of your wort is evaporating at once, this adds a negligible work load to your boil.

So, to put that all together, it should take over 1:15 hours (maybe 1:30 hours) to get 6.5 gallons of wort to a boil.

TL;DR: 6.5 gallons would probably take around 1:30 hours to get to a boil on an 1800w induction burner.

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  • Thanks Chino. Is there any rule of thumb for how much this would be sped up if I put a lid on (until the boil started) ?
    – Matthew Moisen
    Oct 26, 2014 at 6:47
  • My calculations unrealistically assume no loss from radiation, so I am assuming the lid is already on.
    – Chino Brews
    Oct 26, 2014 at 7:09

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