Wattage Necessary

[rodwha]

As it stands I've been using an upgraded electric burner on the stove doing 4 gal boils in a 5 gal aluminum pot making 6 gal batches.

I want to upgrade to an 8 gal aluminum pot so that I can do closer to a full boil. I think I could boil 5 gals, but I doubt I could get much more than that to boil.

So I am considering an electric burner for canning. What type of wattage would be necessary to get 6 gals to boil?

 

[BrewCrewKevin]

The more, the better.

On just 120V, you don't have much of an option. 1500 W is pretty much going to be the biggest you can go.

If you have access to a 220W outlet, go with 30A, or 5500W. If you wire it for 50A, you can run 2 elements at a time.

 

[stlbeer]

Do a search with your favorite internet search tool for electricheat.xlsx. This spreadsheet has all you need to answer your questions.

This is the spreadsheet everyone considering electric brewing needs to have.

To get 6 gallons to a boil (assuming this is wort and not water) - using 4500 watts will take 17 minutes at 95% efficiency.
2000 watts will take 29 minutes at 95%, 1500 watts will take 38 min.

You get the idea. More power=faster time to boil.

Paul

 

[dyqik]

Do a search with your favorite internet search tool for electricheat.xlsx. This spreadsheet has all you need to answer your questions.

This is the spreadsheet everyone considering electric brewing needs to have.

To get 6 gallons to a boil (assuming this is wort and not water) - using 4500 watts will take 17 minutes at 95% efficiency.
2000 watts will take 29 minutes at 95%, 1500 watts will take 38 min.

You get the idea. More power=faster time to boil.

Paul

But be wary, the above assumes that the heat losses from the pot are small, and the 95% efficiency is only really appropriate for an immersed element. You may not be able to get a 1500W external burner to boil 6.5 gal (to boil down for 5 gal in fermenter) at all with the lid off - inefficiency of an external burner, evaporative losses from the wort and heat loss to the air through the walls of the pot may exceed 1500W, meaning you never get there.

 

[Wynne-R]

Hold on StL, I’m not buying those numbers. Here’s the way I figure it:

6 gal = 22.7 L 100 - 20 = 80° C temperature difference
22700mL * 80° C = 1,817,000 calories = 7,613,000 joules = 126,900 watt- minutes

time to boil from room temperature

4500w 28 min
2000w 63 min
1500w 85 min

That’s at 100% efficiency, not counting for heat loss. Heat loss is huge. I run a three gallon pot on a 1300 watt induction plate and at 650 watts I can just barely hold a boil.

 

[dyqik]

Hold on StL, I’m not buying those numbers. Here’s the way I figure it:

6 gal = 22.7 L 100 - 20 = 80° C temperature difference
22700mL * 80° C = 1,817,000 calories = 7,613,000 joules = 126,900 watt- minutes

time to boil from room temperature

4500w 28 min
2000w 63 min
1500w 85 min

That’s at 100% efficiency, not counting for heat loss. Heat loss is huge. I run a three gallon pot on a 1300 watt induction plate and at 650 watts I can just barely hold a boil.

StL's numbers for 2000 and 1500 W are probably about right for raising from sparge temps to boiling - a ~35C temp difference. But the 4500W one in that post is definitely off.

 

[stlbeer]

StL's numbers for 2000 and 1500 W are probably about right for raising from sparge temps to boiling - a ~35C temp difference. But the 4500W one in that post is definitely off.

Right you are. If it's wort, it's not going to be room temp. I started out a bit higher at 150*F, which is probably too high also, but meh. You get the idea.

 

[Wynne-R]

OK, hot wort, as in mash temp. Makes sense.

So, mash to boil, 35° C increase at 95 % efficiency

4500w 13 min
2000w 29 min
1500w 39 min

as Dyqik points out, there is a point that you don't have enough heat to boil.

 

[rodwha]

And that's my question. What do I need to ensure a boil?

I don't mind it taking a bit of time all depending, but I'd like to know where to even begin. If, say, 1300 watts can bring 6 gals to a boil I'd likely want something a bit above that. My upgraded stove burner takes a city of time to get from a mash/sparge temp to boil (30-45 mins?), and I'd prefer quicker, but that depends on the additional cost as I can certainly deal with what I have now.

I use MoreBeer's free shipping on larger orders as I don't mind waiting another day or three to get my stuff. It's not worth another $16-20.

 

[dyqik]

I have trouble boiling 6.5 gallons from mash out on a 9000 nominal BTU/hr gas stove burner with the 8 gal kettle open, but can get there with a lid on or with a 1000W bucket heater/heatstick added. I have no trouble maintaining a boil on that burner though. Assuming that my gas and an electric stove type burner will have similar efficiencies (!) that's about 2600 W equivalent. A 2000W immersed element would probably eventually reach and maintain a boil as it's much more efficient than an external boiler, but I doubt a 1500W immersed element would.

It takes about ~1800W to boil off 0.75 gallons of water in an hour (2260 kJ/kg of water is the latent heat of vaporization of water), which is the kind of boil off rate you should be targeting on a full volume boil. Add a hundred watts or so of heat loss from the sides of the pot, and you need a 1900W heat input to the pot (i.e. after burner efficiency losses) to maintain the boil-off rate you require. With a smaller pot the boil off rate is lower because of the smaller surface area, which also reduces the other heat losses.

Basically, it's really hard to do a full volume (6.5 gal) boil for a 5-5.5 gal batch on a single 20A circuit - 2000W - even with an immersion element. Expect to need to use at least two 1500W immersed elements on separate circuits. For an external burner, figure a 20% drop in efficiency, from 95% to 75%, and up the powers accordingly.

Cheapest option is to add a 1500W heatstick or 1000W bucket heater (bit more expensive(?), but no DIY required) to use alongside your stove burner. Your stove should be on a separate circuit to your sockets in the kitchen already, so no electrical work required. A bit more permanent is fitting a 1500W or 2000W immersion element in your kettle, or adding two to run on separate circuits.

 

[rodwha]

I looked for the spreadsheet info, but was unable to find it.

As we don't own a home I certainly cannot create something that will require modifying electrical wiring. It would seem 120v would be ideal, but it also seems it would be greatly lacking in ability.

I had been eyeing 1500 and 1800 watt burners, but it seems an 1800w would just not cut it.

The only other thing I can think of would be a 240v burner and unplugging the stove.

Are there any replaceable stovetop burners that can be had? When the original burner went out I had him install an upgraded burner, but I doubt it coil boil 6.5 gals or so.

I had approximated my boil off rate to be about 10%.

 

[dyqik]

The trick if you are stuck with 120V is to use two separate circuits to supply the heat. It's likely that your kitchen already has at least 2 separate circuits in it, and your stove is on a third circuit. You can easily use a plug in immersion element at the same time as your stove burner to supplement it. However, you will not be able to do this using an external burner.

As I said above, the easiest option is to use one of these with your stove's upgraded burner. This should get you there fairly easily.
1000W bucket heater

 

[stlbeer]

I looked for the spreadsheet info, but was unable to find it.

http://gnipsel.com/beer/software/beer-software.html

It's the last one in the list.

 

[rodwha]

Looks like what I'll need to do.

Thanks for your help!