Please Explain.. 50% loss to evaporation

[Gamby]

Hi Guys,

After months of reading and setting up my all grain system, today was my first brew. A simple 23 litre Amber Ale, with minimal hop additions.

After some tweeking i finally got my mash temp right and batch sparge, i hit my wort volume in the kettle perfectly at 26 litres, working on 10% evap plus a little more.

Now this is where it went pair shape, i boiled the wort till i hit the hot break, nearly had a boil over but lowered the heat, all good for my 60 minute boil, when it was complete i then ran my wort through a pump and plate chiller into fermenter, when i drained my wort i only had 13 litres ( a loss of 50% ) I was meant to have an reading of 1049 but i had a reading 1060 ( im assuming i concentrated the wort with so much evaporation) can someone please tell me what i did wrong, i though maybe my boil was to vigorous but i checked the temp and it was 90 degrees celcius.

Cheers

Gamby

 

[droid]

some weird schiza goes on during the boil, was it really 26ltrs? Was it 60minutes? How much was left behind in the trub?

Get it out of the kettle and off the trub, check gravity adjust with water addition (pre-boiled if poss) to desired gravity

I always over do the boil now and bring it (over gravity and under volume wort) back up to desired oG because it's bloody near impossible to get the same reduction every time

 

[btrots87]

I would be checking your thermometer if I were you. Water/wort doesn't boil at 90 degrees celsius (unless you were brewing on top of a really high mountain, I'm assuming you weren't).

Other than that I'm only new at this myself so I'm probably not going to be able to help you much.

 

[seamad]

get your thermometer checked, 90C isn't boiling.
1.060 @ 13L if diluted with 3L water will give 1.049, was 16L your target end of boil ?
Did you let the trub settle after the boil ( or whirlpool ) ? If so how much did you leave in the kettle ?

edit: was your gravity correct pre boil ?

 

[The Judge]

How big is your burner? If you're pumping in a ridiculous amount of heat you can evaporate off water at a high rate. The rate of evaporation is dependent on a couple of things, primarily ambient air pressure and heat input. The ambient air pressure thing (low pressure) might explain why your boil temp was so low! But you'd probably have to be living on a mountain, and as far as I know there aren't any in Berwick.

 

[Gamby]

Hi Guys, Why pre boil volume was definitely 26 litres. I know i lost a bit in the lines plus the pump and plate chiller, and as for the thermometer, it was a laser thermometer (point and click ) as it was too hot to put my normal thermometer in. I have a Banjo type burner, high pressure, im putting it down to too higher pressure burn as i heard it doesn't matter how vigorous your boil is it wont get over 100 c in an open vessel. 23 litres was my target volume also.
Oh and it was a 60 minute boil too the second..

 

[droid]

Is your pot big ? maybe a large contact area and not much depth. Regardless, you can't get a boil-over at 90deg can ya?
More initial wort volume or calm the jets or add water after

 

[antiphile]

I gotta agree with all of the posters above. At sea level, (pure) water by itself will only start boiling at 100C. When dealing with wort at around the 1.045 to 1.055 SG, it boils above that (my measurements and research suggest nearly 102C). And as mentioned by many, a higher altitude will reduce the boiling temp, but you'll need to be long way up to see much of a difference.

Might be time to recalibrate your thermometer if you can, or check it at someone's place who lives near the beach.

 

[shacked]

Did you completely drain the kettle when transferring to the fermenter? My first AG I did in a crown urn and was under volume by about 5 - 6L because:

1) my boil off rate was closer to 12.5% than 10%.
2) my urn retains between 3 and 4L of trub and crap after the boil.
3) errr...I also did a 90m boil and only allowed for a 60m boil in my water calcs

 

[contrarian]

The temperature of the boil is a red herring here. It is clearly a measurement error and my understanding is that point and click style thermometers are not accurate on reflective surfaces.

The real issue here is that the pre boil volume was not sufficient to account for losses in the process. The only loss you have allowed for is evaporation at 10% of 26 litres so 2.6 litres. If correct it would leave you about 23.4 litres post boil. Depending on your set up you could easily lose 5 litres that would be left in the kettle deepening on whether you have a ball valve or syphon. I'm guessing if you use a chiller you have a ball valve. One place to start is to fill your kettle with water and work out how much liquid is left in the kettle once it won't drain anymore and factor this is to your preboil volume. You have also said that there were losses involved in the chilling process that also weren't factored in when you calculated your boil volume.

As stated above the wort loss associated with evaporation was 3L assuming your pre boil Gravity was on target, the other 7 litres are process losses that you need to account for in your pre boil volume.

 

[Gamby]

Cheers Beer God, I do have a ball valve with an internal dip tube, its very efficient, an estimate only but around 300mm left in the kettle. Your correct though, it was just a simple rookie error not knowing my losses to evaporation and also the cooling process. I am going to do a test run with water today with a lower heat boil ( just a small rolling boil ) and count my evaporation and cooling losses over 60 minutes and input that into my brewing software.

 

[contrarian]

Depending on the diameter of your kettle 300mm could easily be around 5 litres. For example in my kettle which is a 450mm diameter 10mm of water height is equal to 1.6 litres.

I also have a high flow reg and find that to maintain a rolling boil with my burner I need to have the reg set to minimum and also turn it down at the burner. Your eyes are probably a better measuring tool for a boil than a thermometer!

Boil off will also vary based on a variety of environmental factors so it is hard to be 100% exact every time. From discussions with other Brewers it seems that litres per hour is more consistent than a percentage of boil volume so that might be worth considering as well.

The first few brews are a pretty steep learning curve but you are still making beer and I will bet it tastes great, even if there's a bit less than you were hoping for!

 

[Gamby]

Sorry Contrarian, i meant to say 300 Millilitres not 300 millimeters.. I will take on board the litres per hour boil off, i think that is a better estimate overall. Also , and this may have been a big no no, seeing i only produced 13 litres, i did add water to the beer, should i have done that or have i ruined the beer, appreciate the OG will be lower. Thanks for the tip with the burner, im pretty damn sure i had that think cranking.

 

[TheWiggman]

I will bet a bag of snakes and a Mars bar that you didn't boil off 13 litres in 60 mins in a standard pot. If you did, pass on the sorcery to the food and chemical industry where they could take advantage of the massive energy savings for evaporation processes. I assume you had a pot that is taller than it is wide. If you had a flat shallow pan I might be more inclined to believe it.

Evaporation is typically a function of surface area. This is primarily because the heat put into the water can either be utilised as conversion of liquid to vapour or losses to the environment on the pot/pan's surface. The larger the surface area of the pot, the more heat from your boiler is ejected to the ambient air, and the less liquid converted to steam. There is also other factors like pressure, air movement etc. but you should be getting a figure of 4-5l/h, not 13.

Where you went wrong I don't know, but if you provide your pre-boil gravity it would be a lot clearer. There has to be a measurement error somewhere or there is a leak you don't know about.

 

[MastersBrewery]

yeah those jet burners can easily boil 80L if you were looking like a boil over for a considerable portion of the boil time 13L evap would easily be possible. slow the boil down so it's just rolling over.

 

[Gamby]

The Wiggman i am using a converted 50 Litre Keg with Ball valve and dip tube.

 

[TheWiggman]

I've got the same Gamby, with a 3600 W element. I get about 4.5l/h. Most brews I'll get a boilover and have to keep turning the power off as I can't throttle my power.
When you do your volume estimates next time get a tape measure and measure from the keg bottom to the liquid level. Boil for 1h, and measure again. Work out the volume lost based on the difference. That's the most accurate way to determine losses during the boil.

V (litres) = (π x 0.2052 x difference in mm) /10

 

[hellbent]

use the Biabacus software, it will work it all out for you.

 

[Gamby]

Hi Guys, well i done a test run with water today, put in exactly 26 litres, boil for an hour on low heat (maintaining boil ) and drew out near on exactly 20 litres with 1 litre remaining in keg ( i normally draw out more from the keg as i use a pump but the test was done just by pouring out using gravity). So thats 5 litres per hour plus losses to equipment etc. Its better but still alot more than the beersmith software uses as a default setting of 10% boil off.
Hellbent i have never heard of the Biabacus software, i might check it out. Thanks for the formula Wiggman, who would have thought brewing beer would be so scientific.
Great forum, great brewers with so much knowledge, cheers again to all.

 

[Nizmoose]

5 litres per hour seems very normal. I don't really know why beersmith and many other programs use % as a loss parameter. I typically boil off around 3.5L per hour, if I'm doing a 10L batch it'll be a higher percentage than if I do a 15L batch, the percentage is not a helpful number in my opinion, stick with knowing the exact boil off per hour for your system would be my advice. I understand that the physics of this is not as simple as that but anecdotally going by litres per hour is more helpful than percentage especially if your boil volume changes much recipe to recipe