Reducing evaporation rates.

Post by **Monkeybrew** » Sun Apr 05, 2015 10:07 am

Hi

I use a homemade 60L plastic boil kettle that has 2 x 2.4kw elements. The diameter of the bucket/boiler is quite large (can't remember what size atm) and I have an evaporation rate of 18-19% per hour!

I was thinking of cutting a 120mm diameter hole in the centre of my lid and then keeping the lid on during the boil.

I assume that this will lower the evaporation rate, but will it cause me any other issues?

Cheers

MB

jack_c · Post by **jack_c** » Sun Apr 05, 2015 10:29 am

Do you keep both elements on during the boil? My volume into boil is 30l on a 2.6kw element, and around 10% evaporation loss and the boil is vigorous. If you are using both, maybe this is contributing to the high evaporation? I'd think once boiling one element would be more than sufficient.

No idea about negative consequences of a hole in the lid. There was a post recently discussing impact of boil length, evaporation and DMS (viewtopic.php?f=2&t=70677 regarding this blog post http://brulosophy.com/2015/03/11/the-im ... t-results/)

There's some stats about 5% evap being ideal to get rid of off flavours.

Disclaimer: I have no idea about the validity of any of the above posts, just interesting reading that could apply to reducing evaporation rates...

Goulders · Post by **Goulders** » Sun Apr 05, 2015 10:32 am

MB Aleman wrote about this recently several times on some threads, but maybe on TBF. You should be aiming for 10-12% per hour. Once up to the boil, just reduce to one element.

Post by **Monkeybrew** » Sun Apr 05, 2015 10:57 am

Goulders wrote:MB Aleman wrote about this recently several times on some threads, but maybe on TBF. You should be aiming for 10-12% per hour. Once up to the boil, just reduce to one element.

Ok, I'll give this a go on my next brew, think that I might have tried this on my first brew

but then read somewhere that a harder boil was better.

It's all a balancing act I suppose.

Cheers to you both.

MB

Wonkydonkey · Post by **Wonkydonkey** » Sun Apr 05, 2015 9:30 pm

I think it's the first 15-20 mins to get a good hot break, then a steady boil.

I guess 2 elements going all the time is a bit ott.

I only got 1 x 3kw in my Thermopot , it boils 65lt fine to get a good hot break it gets the full 12.5amps then I lower it to 6-7amps for a steady boil. I also only have the lid lifted on one side. by using a spoon or a small cup as the spacer I can lift the lid without burning my fingers on the steam that's escaping. And if I think it's gonna boil over I can lift the lid to let some heat to escape. I recon I loose about 10-12lt in a hr.

Edit: I should have said I have only done 2 x 50lt brews in it, and the 10-12lt is lost from all angles, its what I get in the FV after the boil.

I must have had a few when I first replied

Troutman47 · Post by **Troutman47** » Mon Apr 06, 2015 10:28 am

Hi MB,
It sounds like you have the same setup as me, I would use both elements to gets the hot break then turn one off. However, this would only give me a gentle rolling boil, around 18% evaporation over 1.5 hrs and hazy beer!
So I bought a simmer stat and fitted it to one element which I turn down after the hot break, this has given me a more vigorous boil, improved clarity but 22% evaporation over 1.5hrs!
I've been thinking about a hole in the lid too but wanted some kind of flexible flue to take the steam away.
I don't see why there would be problems with DMS etc. as the steam will still be taken away, but I stand to be corrected.

Regards

vacant · Post by **vacant** » Mon Apr 06, 2015 12:46 pm

Monkeybrew wrote:I use a homemade 60L plastic boil kettle that has 2 x 2.4kw elements.

I've been using the same as you for years. I have a spreadsheet to calculate liquor quantities. It has two sections for heating:

2 elements 9 litres/hour
1 element 3.8 litres/hour

When boiling, heat is lost at a constant rate through the sides/base so some energy from one element goes there, the rest to evaporation. When the second element is switched on 100% of that element's energy goes to evaporation.

These days I run two elements for 30 minutes for maximum agitation/hot break. Then down to one element and copper hops added for a further 30 minutes. 60 minute boil in total (normal additions 10 minutes before the end of boil etc of course).

nobby · Post by **nobby** » Mon Apr 06, 2015 3:15 pm

If you are loosing too much liquid through evaporation why don't you just add some more boiled water to make up the loss ???

GAZ9053 · Post by **GAZ9053** » Mon Apr 06, 2015 3:40 pm

I did this

Plus it stopped me getting a rollicking for condensation dripping down the walls

jack_c · Post by **jack_c** » Tue Apr 07, 2015 11:11 pm

Is that the bubblewrap coated in tinfoil stuff they sell in homebase etc as insulation? SWMBO is irate I use the cotton throw as my insulation around the boiler during mashing. Considered the bubblewrap tinfoil stuff but was worried about it...

Also, how did you attach the vent to the glass? A flanged attachment and cable ties?

Very nice!

GAZ9053 · Post by **GAZ9053** » Wed Apr 08, 2015 5:21 am

The bubble wrap is the that sort of stuff although I got from eBay. It's a 410x410 piece of perpex with 100mm hole then a extractor fan outside vent fastened in to fit tube to.

Post by **Monkeybrew** » Wed Apr 08, 2015 11:11 am

GAZ9053 wrote:The bubble wrap is the that sort of stuff although I got from eBay. It's a 410x410 piece of perpex with 100mm hole then a extractor fan outside vent fastened in to fit tube to.

Now you've got me thinking.........

This kind of setup would allow me to boil in my shed, rather than having to brave the elements outside of it

I have obviously got power to my shed, so could easily fit an extractor fan into one of the gable ends, and easily fit the ducting to my boiler lid.

This is my current predicament

Cheers

MB

GAZ9053 · Post by **GAZ9053** » Wed Apr 08, 2015 11:14 am

I didn't fit the full extractor fan just the plastic outside vent cover. The duct just hangs out the window.

Post by **Monkeybrew** » Wed Apr 08, 2015 4:52 pm

GAZ9053 wrote:I didn't fit the full extractor fan just the plastic outside vent cover. The duct just hangs out the window.

Even better then, suppose it is like running a heavy duty tumble dryer.

I also imagine that it will help with a decent rolling boil on one element.

Cheers

MB

MarkO'B · Post by **MarkO'B** » Wed Apr 08, 2015 10:58 pm

Hi,

I looked at a set up using exactly what you describe, 60l pp bucket and two 2.4kw elements, last Friday. The brewer had done exactly what you describe, the boiler was in a shed and had a fixed angle chimney pipe which connected to a removable elbow and down pipe which fitted the lid with a hole in the centre. He was quite chuffed with it and to be fair, it looked like a good set up. The guy knows what he is doing. I have no idea what losses there where, but the report was that it worked a treat.

I also believe he did an initial boil with the two elemenents then dropped to one.

Slightly off topic: any chance on a link to the eBay insulation used above? I am liking that. Thanks.

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