Evaporation From Boiler Test.

[mschippr]

Hi,

Today i did a evaporation test in my boiler in preparation for my first AG in the coming weeks. I'm setting my equipment for use with Beersmith. My pot is a SS 59L and it is quite wide (500mm internal).

I put 35L (17cm) of water into it and kicked off my italian spiral. Lid off once boiling began (95 degrees) and let it go at a rolling boil for an hour. After an hour there was 24L (11cm) left.

Did i do this correctly? 11L of evaporation seems a lot to me.

Your expertise is greatly appreciated.

MARK.

 

[3G]

Yep, sounds right. With an opening of 500mm there is a large surface area. To reduce evaporation you can reduce the boil or partially cover the lid. Dont totally cover of course as the evaporation will reduce DMS.

 

[Bribie G]

I'm all electric with an urn and two days ago did a boil with about 35L start and got around 24 into the fermenter. It was a 90 min boil so I was expecting a good 'attrition rate'. Probably the urn wasn't as fierce as a gas ring burner, but sounds like you are more or less on the money

 

[razE]

Yep, sounds right. With an opening of 500mm there is a large surface area. To reduce evaporation you can reduce the boil or partially cover the lid. Dont totally cover of course as the evaporation will reduce DMS.

Can you tell me what DMS stands for? Sorry still pretty green. Soon to do my first AG

 

[Aaron]

I used to use an aluminium pot of a similar size and got a similar result.

Can you tell me what DMS stands for?

http://letmegooglethatforyou.com/?q=dms+brewing

 

[bradsbrew]

Can you tell me what DMS stands for? Sorry still pretty green. Soon to do my first AG

AHB Wiki: Words and spelling, Discussion Topic

Alot of acronym meanings here too

AHB Wiki: Words and spelling, Discussion Topic

 

[mschippr]

Thats good then, Puts my mind at rest. Now i just need to try it with the real thing and not just tap water.

 

[cubbie]

After a brew on Saturday I was thinking about how I do my boil and the timing of it. What should be the correct/suggested process?

I batch sparge and normally i start the burner when I take the first runnings however this weekend I started once I had taken all my runnings (as I wanted to take a more accurate pre-boil SG). Thoughts?

Do you have a lid on your kettle until the boils starts? And it seems logical but do you start timing your boil from when you turn the gas on or when it starts to bubble or do you wait a bit longer?

I use an immersion chiller and when I dump this in at 15min the boil stops for a short while, do you continue timing or as I do stop the watch and then start again once it gets back up to a boil? If you stop, what sort of adjustments should you make re hop/bitterness calcs?

Anyway just a few thoughts. For a 60min boil it may take 80 min to complete (bringing up to boil and immersion chiller etc)

 

[peas_and_corn]

Start timing your boil once it starts 'rolling'

 

[buttersd70]

A/ I batch sparge and normally i start the burner when I take the first runnings however this weekend I started once I had taken all my runnings (as I wanted to take a more accurate pre-boil SG). Thoughts?

B/ Do you have a lid on your kettle until the boils starts? And it seems logical but do you start timing your boil from when you turn the gas on or when it starts to bubble or do you wait a bit longer?

C/ I use an immersion chiller and when I dump this in at 15min the boil stops for a short while, do you continue timing or as I do stop the watch and then start again once it gets back up to a boil? If you stop, what sort of adjustments should you make re hop/bitterness calcs?

A/ once used to your system, particularly if repeating recipes, you will get to a point where you know what your efficiencies/gravities will be, and you can just start to boil as soon as first runnings are in. If in doubt of efficiency and BG (such as if you change your system or method, or for a different recipe), then you can wait, mix, and test if you choose to. You will probably find that after a while, it becomes unnecessary, as you will start hitting targets more consistantly.

B/ Time the boil from when it starts to actually boil. You could have it covered whilst coming to the boil, to retain heat and bring it up faster, but it should be uncovered for the boil time itself, to allow for DMS to be driven off in the steam.

C/ ignore the drop in temp when putting in the chiller, it would only be a minute or 2 before it starts boiling again anyway.

2c

 

[cubbie]

A/ once used to your system, particularly if repeating recipes, you will get to a point where you know what your efficiencies/gravities will be, and you can just start to boil as soon as first runnings are in. If in doubt of efficiency and BG (such as if you change your system or method, or for a different recipe), then you can wait, mix, and test if you choose to. You will probably find that after a while, it becomes unnecessary, as you will start hitting targets more consistantly.

B/ Time the boil from when it starts to actually boil. You could have it covered whilst coming to the boil, to retain heat and bring it up faster, but it should be uncovered for the boil time itself, to allow for DMS to be driven off in the steam.

C/ ignore the drop in temp when putting in the chiller, it would only be a minute or 2 before it starts boiling again anyway.

2c

Cheers,

I pretty much do A and B for every brew, though I will start doing C.

 

[Thirsty Boy]

After a brew on Saturday I was thinking about how I do my boil and the timing of it. What should be the correct/suggested process?

I batch sparge and normally i start the burner when I take the first runnings however this weekend I started once I had taken all my runnings (as I wanted to take a more accurate pre-boil SG). Thoughts?

Do you have a lid on your kettle until the boils starts? And it seems logical but do you start timing your boil from when you turn the gas on or when it starts to bubble or do you wait a bit longer?

I use an immersion chiller and when I dump this in at 15min the boil stops for a short while, do you continue timing or as I do stop the watch and then start again once it gets back up to a boil? If you stop, what sort of adjustments should you make re hop/bitterness calcs?

Anyway just a few thoughts. For a 60min boil it may take 80 min to complete (bringing up to boil and immersion chiller etc)

Hey Cubbie,

This is what I do, and I dont think its so far from standard that there will be too many howls of protest. I too batch sparge.

I start my flame as soon as I have liquid in my kettle, usually with the lid on - once I have my full volume of wort in the kettle and its getting "close" to a boil, I take the lid off because otherwise it might just boil all at once and the first you know will be the hissing of the boilover - When the boil begins and it has boiled for 30 seconds or so and I am sure its all well mixed together, I turn the flame off for a second, take a pre-boil refractometer sample and double check the pre-boil volume - flame back on, start timer and watch it till the worst of the foaming is over and I dont have to worry about boilover any more - then I analyse the sample and work out whether I need to add any DME or water, or time to the boil to hit my gravity & volume targets, then I work out if I need to adjust my hopping plan - after the kettle has been boiling for 30 mins, I add my bittering hop addition and continue with the remaining 60mins of boil (90 mins total)

I am no-chilling at the moment, but when I used to use an immersion chiller... I just whacked it in there with 10 or 15 mins to go and didn't worry about stopping the clock. Even if its not actually "boiling" for a minute or two the liquid is still hot enough for the alpha acids to be isomerising at nearly full pace, so those couple of minutes will make virtually no difference. I say ignore them. which is the easiest option as well, so everyones a winner.

Thats just the way I do it... but its a method that give me plenty of time to work out the things I need to without rushing and lets me consistently hit my targets on the head.

hope that helps a little

TB

 

[Screwtop]

That's around 31% boil-off cubbie which is pretty high. Still, thats the boil-off value for your system and so be it. A little tip if using beersmith, because it requires boil-off loss to be entered as a percentage, just be sure to adjust the percentage for each recipe to achieve your loss (11 Litres per hour) by adjusting the percentage until the boil-off loss figure equals 11 litres for a 1 hour boil. I personally don't like the percentage for boil-off in Beersmith as the amount boiled off depends upon the surface area of the kettle, size of the opening at the top of the kettle, ambient temp, airflow around the kettle/heat source, length (time) of the boil and how agressively you boil. It will be the same for each batch in your kettle so long as those parameters are reasonably similar for each boil, no matter what the pre-boil volume. So the percentage thing can result in your post boil volume calculations being out when applying the same percentage boil-off to different pre-boil volumes. Best to stick to the volume of boil off which occurs in your system for each batch, that way your calculated post-boil volume will be correct for every batch no matter what the pre-boil volume.

Screwy

Edited to add some parameters

 

[fraser_john]

I find my boil off rate changes, depending on what the conditions are for the day! If I have my fan (read PT Mustang on takeoff!!!) on to bring fresh air into the brewery, my evaporation rate goes higher, considerably so. Cooler damp days tend to reduce the evaporation rate!

According to Promash, I get anywhere from 10% to 14% evaporation rate from a 55 litre starting volume, depending on conditions! Kinda frustrating really as I cannot get consistency.

Wondering if a kettle lid with an exhaust pipe/vent would help...aka those big copper kettles in commercial breweries?

 

[cubbie]

That's around 31% boil-off cubbie which is pretty high. Still, thats the boil-off value for your system and so be it. A little tip if using beersmith, because it requires boil-off loss to be entered as a percentage, just be sure to adjust the percentage for each recipe to achieve your loss (11 Litres per hour) by adjusting the percentage until the boil-off loss figure equals 11 litres for a 1 hour boil. I personally don't like the percentage for boil-off in Beersmith as the amount boiled off depends upon the surface area of the kettle, size of the opening at the top of the kettle, ambient temp, airflow around the kettle/heat source, length (time) of the boil and how agressively you boil. It will be the same for each batch in your kettle so long as those parameters are reasonably similar for each boil, no matter what the pre-boil volume. So the percentage thing can result in your post boil volume calculations being out when applying the same percentage boil-off to different pre-boil volumes. Best to stick to the volume of boil off which occurs in your system for each batch, that way your calculated post-boil volume will be correct for every batch no matter what the pre-boil volume.

Screwy

Edited to add some parameters

i think you mean mschipper. My rate is 15% max.http://www.aussiehomebrewer.com/forum/style_emoticons/default/icon_cheers.gif