Boil Volume Questions...

[Wez]

On my last brew my post boil volume was 57L I ended up with 45L in FV’s, that’s a 12L loss, first question – how does this compare to other peoples boiler losses? I used a 100L SS boiler there were around 200g hops.

Second question…I want to target 60L into FV’s on my next brew which I calculate will require an 85.7L pre boil volume – is this a bit too much to risk in a 100L SS boiler?

Third question, I’ll be stopping sparging at around 1.020 – 1.015 so doubt that I will collect the 85.7L pre boil volume, would you recommend topping up to pre boil volume before the boil or topping up FV’s after?

Thanks, Wez

 

[BrewStew]

only one way to find out with the boil when i fill my boiler dangerously near the brim, if it looks like it's about to get out of control i quickly drop some spare wort in to kill the foam and open the tap to let some out till it's a safe volume, then return it when some has boiled off.

as for topping up or chucking in the fermenter, i've done both now and never noticed a difference... i suppose if your water is higher in chlorine/chloramines you might be risking a tcp taste if you top up the fermenter though, but i've never had that problem

 

[steve_flack]

On my IPA at the weekend I oversparged and ended up with 49L. It took 2 hours to boil it down to around 41L. Normally I boil for an hour and lose around 4L in 45L (Around 9% per hour).

You're losing more than 20% which does seem a tad excessive (what's your boil time - 2 hours?)

As to your third question, I'd boil the boil length you intended. If you do a smaller more concentrated boil then your hop calcs will be out.

 

[Buzz]

On my last brew my post boil volume was 57L I ended up with 45L in FV’s, that’s a 12L loss,

Do you mean the pre-boil volume was 57L. If not you must be spilling some :shock:

I didn't think the loss was too bad if it was pre-boil at 57L and a 2 hour boil. 9% in the first hour would be minus 5.1L, 9% in the second hour would be minus 4.7L leaving 47L. Then, less about 2L for deadspace/loss to hops and trub etc. would give you 45 bang on

 

[Wez]

I should have explained in the initial post:

My last brew :

Pre-Boil 68L
Post-Boil 57L which is 11 lost which is 16.2L lost over a 90 min boil, so that is 10.8% per hour (that seems about right to me?)

I then went from 57L after the boil to 45L into the FV, so lost 12L to the boiler / hops / trub……(none spilled :lol:)

12L is lots to lose isn’t it!

I hit, 75% efficiency though?

 

[steve_flack]

12L is a lot to lose to hops. I use pellets and I don't lose anything like that amount (a couple of litres tops).

 

[Wez]

I'm going to spend an hour re-calibrating tonight just in case I have my volume measurements wrong.

I use a steel rule for this, but have been though the calibration process once already :hmm:

 

[brewzone]

Second question…I want to target 60L into FV’s on my next brew which I calculate will require an 85.7L pre boil volume – is this a bit too much to risk in a 100L SS boiler? Thanks, Wez

I like to use a maximum of 85% of the kettle volume to be sure I don't get a boil over.

So 85L sounds fine to Me!

 

[spearmint-wino]

I've been thinking my evaporation loss is quite high too, around 6ish litres loss in a 31 litre length, so minus about a litre for 100g or so of hops and deadspace = 5l = 15%. Does that sound normal or on the high side for 60mins?

[sorry for the hijack]

 

[MEB]

I lose around 8L during the boil in a 30L batch. But that's due to the fact that one element isn't enough for a nice roilling boil and i don't get enough break. Both elements and it boils fiercely so i get a lot of evaporation but a good break. :|

 

[Vossy1]

Wez, you need to know 3 things before deciding pre boil volume

1, Loss to equipment
2, Loss to hops
3, Loss to evapouration

1.) First thing you need to do is find out what the loss to your boiler is.
Part fill it, open the tap and when the flow stops, close the tap......now measure what's left in your boiler...that's the loss to your boiler.

2.) I work my loss to hops based on 1kg leaf hops absorbing 6ltr of wort (G Wheeler)

3.) You can only work this out by knowing the other 2 first

My typical batch is 60ltr and for this I need 76ltr pre boil volume.

1.) Loss to equipment is about 3ltrs
2.) Loss to hops depends on batch, last batch used 320g of EKG so 1.92ltr loss
3.) I lose roughly 10%/hour so 90min boil = 15% = 11.4ltr

For the above batch I boiled 77ltrs and got 60.5ltr to the fv which was as close as dammit

You won't get the same evapouration rate boiling larger volumes with the 2 elements, as you do with smaller volumes

 

[Aleman]

I lose roughly 10%/hour so 90min boil = 15% = 11.4ltr

<Pedant Mode = "On">

Actually Its not, In the first hour you loose 10%, in the second hour you loose 10% of the volume you had at the start of the second hour. So If you had 20L in the boiler to start with you would have 18L left after 60 minutes, and loose an additional 1.8L in the next 60 minutes. as you are only boiling for 30 of those you can halve that and get a total loss after 90 minutes of 2.9L. 15% of 20L is 3L



Ok I'll grant you that it is close though

<Pedant Mode ="Off">

 

[Vossy1]

Thanks for putting me straight :lol: :lol:

After the first hour there is less liquid being boiled by the same power of elements, so I would expect a higher evapouration rate in the second hour :hmm:
Close enough...as you say...although I am slightly disappointed...I was expecting a

4.)
5.)

etc etc :lol:

 

[Wez]

I'm going to get my trusty (or not so trusty) steel rule and boiler back into the kitchen for a calibration check, then i'll note down everything as I go along and see what happens :thumb:

What you've all said makes sense, thats why I posted it this morning, christ knows what you'd have all said at 1am :rofl:

 

[Vossy1]

Wez, is that strainer making an air tight seal on the nipple?
I had a look at my boiler this am and I reckon the bottom of the nipple is around the 10ltr mark.

4.) Cooling loss 4%, so at switch off you need 62.4ltr according to Beersmith

I wondered why I never have 3ltrs left in the boiler after draining the wort...now I know
The fight goes on :lol:

 

[Wez]

Ah, so you think if the strainer isn't making an airtight seal i may have left 10L below the 'nipple' (you could have said tap, you just wanted to say nipple..didn't you)

I'll do a test with the hop strainer attached :thumb:

I am right in assuming that as long as it's airtight it should drain almost to the bottom am I :hmm:

 

[Vossy1]

I am right in assuming that as long as it's airtight it should drain almost to the bottom am I

Yep...will probably leave about 3 ltrs

 

[Wez]

Ok more questions!

I checked how much loss there would be to the boiler and V1 was correct 3L, so here are the figures for my last brew


Pre Boil 60L
Collected 38L in FV's

So taking into account boiler dead space loss 3L and loss to hops ~2L a total of 55L it would appear that over 1.5hrs I boiled off 17L from a 60L starting volume :shock: thats 28% lost to boil evaporation! I'm using 2x 2.75kw elements for the duration of the boil, one just doesn't cut it due to the location and draft. Has anyone else experienced loss like this and apart from try to insulate the boiler and just use one element is there anything I can do?

 

[Vossy1]

I was just about to ask you how you got on.
I thought you were going for 87ltr boil volume?

Anyway, the elements will be quite fierce for the first few uses, but they will gradually fall off with regard to evapouration.
I am very surprised about the 28%...that's really high :hmm:

is there anything I can do?

Make man sized brews god dammit :rofl:
Up the batch size/pre boil volume for the 1st 5 or so batches until the elements settle down.
With a larger batch size you'll get less evapouration anyway.

 

[Wez]

I'm going to go for a 60L brewlength at the weekend, so i'll sharpen my pencil and work out some volumes later.

I feel a batch of "Thirst Gold" coming on :thumb: