Is My Gas Burner Strong Enough?

[paulwolf350]

Just boiled 12.5 litres of water in 40 mins, it held a boil for a further 15 mins without stopping, till I turned it off, but it was only just boiling. I am wondering if this will be big enough to do a 26 litre boil for 1 hour

The bigest pot i currently have is a 15 litre jobbie so cannot test the full 26 litres yet, just wondering if I should persevere with this burner or plan on getting something better?

Paul

 

[Steve]

Just boiled 12.5 litres of water in 40 mins, it held a boil for a further 15 mins without stopping, till I turned it off, but it was only just boiling. I am wondering if this will be big enough to do a 26 litre boil for 1 hour

The bigest pot i currently have is a 15 litre jobbie so cannot test the full 26 litres yet, just wondering if I should persevere with this burner or plan on getting something better?

Paul

Paul - what kind of burner are you using?

 

[Sammus]

12.5L in 40min? I wouldn't count on it being enough... unless that 12.5L started as ice, then maybe.

 

[paulwolf350]

Paul - what kind of burner are you using?

Its a 2 burner cooktop out of a comercial kitchen, I just hooked it up to my BBQ regulator and fired it up, the burner is 200mm in the shape of an X

Paul

 

[paulwolf350]

12.5L in 40min? I wouldn't count on it being enough... unless that 12.5L started as ice, then maybe.

Nah just regular old tap water

Paul

 

[Sammus]

Maybe try a high pressure reg, pretty hard to get away with low pressure unless you have one of those 'mongolian' burners.

 

[np1962]

The BBQ reg. probably not helping, low flow rate.
May be worth trying with an adjustable reg. but no guarantees it will do he job.

Nige

Edit- beaten by Sammus. :mellow:

 

[QldKev]

I would say no..
My 3 ring burner 29L goes from water filter temp to 69degrees C in < 30min

I wouldn;t recommend anything less than the 3 ring when it comes to the full boil.

QldKev

 

[paulwolf350]

I wouldn;t recommend anything less than the 3 ring when it comes to the full boil.

QldKev

thanks, I might try a higher pressure reg, my old man has one.
I dont think the burner would hold boil at the moment with 29l. if no good with new reg, a 3 ring it is. B)

any idea what pressure I should be aiming at?

Paul

 

[Carbonator]

I got a 3 ring with reg for sale, because I saw the light and converted to electric!

Cheaper, safer!

 

[paulwolf350]

I got a 3 ring with reg for sale, because I saw the light and converted to electric!

Cheaper, safer!

Convince me! why is electric so much better?

Paul

 

[Carbonator]

Convince me! why is electric so much better?

Paul, from an end-user point of view, Elec is cheaper, because retail LPG is so damn expensive per heat gained/$.

Secondly, elec has no CO/user air poison issues when it comes to heating.

Sorry I can't be more specific, but I AM CORRECT!

OPEN FLOOR!

 

[QldKev]

The floor is open

how long does it take to boild with electric, how well do you maintain a rolling boil ??????

One Watt (W) is 1 Joule per second, 1W=1J/s.
a kW=1000W=1000J/s.
There are 60*60 seconds in an hour, so a Kilowatt hour is
3600*1000 J=3.6*10^6 J.
One mega-joule is 1 million Joules, 1MJ=10^6 J, so
1 kWh=3.6 MJ.

My 3-ring burner is the bottom end of the LPG systems @30mj/h as it only runs low pressure.

2400w element (max for 240v 10amp socket) = 8.6mj

I know heating externally is not as efficient as an electric probe in the water, but.....



QldKev

 

[Carbonator]

how well do you maintain a rolling boil ??????

Just a guess with the 3 ring camping burner, a "rolling boil" over 6 hours will cost 25-30 litres of LPG and about $5 with elec.

Still OPEN FLOOR for opinions on this, as I have not experimented with different burners.

 

[paulwolf350]

At the moment I am still undecided which way to go,

I did the sums and come up with the same results as kev
the manufacturer claims 32 Mj for the unit, i assume thats 16 Mj for each burner

16Mj is still more than a 2400 watt element (8.64 Mj)

but if it is going to consume 5kg of gas, it is going to cost a bit to run, I probably would be better off going electric right from the start

Paul

 

[Ducatiboy stu]

there is a standard calc for how many Mj it takes to heat a certain amount of water to boiling point...i just dont have it...... :unsure:



Elec may be cheaper, but gas will got it boiling quicker..


You also need to take into account that you will need a seperate 15Amp cct to run a decent elec setup...


You can buy a lot of gas for the cost of a 15Amp cct

 

[troopa]

3600W element on a 15amp outlet gets me from tap water to 68degrees in about 40 mins
Mashout with BIAB - 65 up to 75 degrees takes me 15-20 mins with the bag in the liquor stirring constantly and swinging the bag around to stop it burning
From mashout - 75 to 102-104degrees takes nearly 30 mins. At this point i crank the variable controller i have back to about 75% to keep a steady temperature otherwise it gets WAY HOT

Thats for a 23 liter batch, (17ish% boil off)... damn my 400mm diameter pot

hmm my calculations suck but 3600w @ 1.5 hours running time at 10.8900c / kWh comes in under a dollar per brew ( i only brew on Saturday or in off peak times)
BTW for those that use electric and didnt know.. Energy Australia are now rolling out their smart meters to all houses around Australia and all you have to do is call em and they will install it within 30 days
This will give you Peak, Off peak and Shoulder rates
http://www.energy.com.au/energy/ea.nsf/Con...W+TOU+Res+Rates

Tom

edit: spelling and linky

 

[Ducatiboy stu]

For those that are smart, I Would NOT get a smart meter, due to the fact that they use time-of-day metering..

Yep...you get charged a different rate depeding on the time of day you use power..... read the fine print

Older meters just rely on what you use over a 3 mnth period

 

[QldKev]

LPG depending on purity has about 30mj per Litre, there is 2L per Kg

So my 8.5Kg refill has 510mj of energy stored.

510/30mj hr = 17hr run time(on full)

Under $2 per brew, not really worth worrying about.

LPG gives me portability, if I want to brew at a mates on the weekend no problems.
If I move I don't need to get another 15amp socket installed.

(There is a potential difference that if using high pressure LPG systems there is a higher % wastage. Making the cost per brew higher.)

-- I just checked my brew book and can confirm I have had 9 brews on the same bottle.

But we are now talking within $1 a brew.



QldKev

 

[paulwolf350]

just googled this up, for the mathemeticians, to work out how much energy you need to heat water -

You would use the equation ΔQ = mcΔT , where ΔQ means change in energy (or energy required in this case), m is mass of water, c is specific heat capacity, and ΔT change in temperature.

Water's specific heat capacity (energy needed to raise 1kg by 1 degree K or C) is 4200J Kg^-1 K^-1, so, if we put your numbers in: so for 29 Litres, I will assume 29 kg. And we want to raise it 70 degrees, (nearly boiling)
= 29kg x 4200J Kg^-1 K^-1 x 70C (70 degress kelvin)
= 29 x 4200 x 70
= 8526000 or 8.526 Mj

so assuming that these numbers are correct, a 2400 watt element is only just big enough, and my burner is crap - 13 x 4200 x 70
- 3.822 Mj in 40 min
which equates to 5.79 Mj for an hour or 1.6 KW

even if it was 60% efficient it should boil my pot in 24 mins

Paul