Boil off amount

[Andyhull]

As i have said in other posts i have a 30+ ltr mango tub boiler (+ being a litre or two) and as such have been told i will struggle to do 23lt/40pint brews.

My question is, if i was to place the lid on the boiler leaving a 2 inch or so gap would this not reduce the amount of boil off?

In doing this would i be risking off flavours due to those veggie smells flavours if i don't allow it to boil off un covered even though im still letting it steam off to e certain extent?

Sorry for these questions but i want to keep the kit i have as i like the size of it as it's not too intrusive in my small shed :cry:

 

[evanvine]

You need to know the reduction rate of your boiler.
With 1 element mine reduces at 2.5 ltr/hr.
For a 90min boil this would be 3.75 ltrs.
With my system I need to finish with about 24 ltrs in the boiler to get 23 ltrs in the FV.
I sparge to 27.75 ltrs and put the 90 min hops in before the boil start, this prevents "boil over".
Do not put the lid on, or at least have a 4" hole in it to allow egress of the nasties.

 

[Andyhull]

So you start your boil with around 27.75lts to end up with 23ltrs.
I can safely boil 28ltrs in my 30+ litr boiler i have had it within 3" of the very top with water on a rolling boil and it didn't overflow!

 

[evanvine]

Just be careful Andy, water does not fob up like wort!

 

[Andyhull]

Hmmmmmmm,

I watched a vid on youtube and a guy used a spray bottle with cold water in it to controll the boil at the beginning.
Everytime it foamed up he gave it a quick sray to calm it down.

The thing is after 10 mins into the boil with boil off it would be safe as houses and a larger boiler would be un-neccessary and as stated i have a small 8ft x 6ft shed so would take up more room.

I can get a 45lt blue barrel pretty cheaply (£8) and can convert it easily using the parts off the current boiler but im reluctant to do so as i say due to space!

 

[evanvine]

No need for cold water spray, use First Wort Hops!
I put my 90 min hops into the boiler before sparging.

 

[rpt]

You could start with slightly less wort in the boiler and top up as it boils off. You could do this with water or with mashed wort that you hold back from the mash tun. Or you could top up with water in the FV at the end (I think this is known as liquoring back). You may need to slightly increase hops due to the higher gravity. Maxi BIAB uses these techniques and the same principles can be applied even if you aren't doing BIAB yourself.

 

[Andyhull]

Is there no detriment to liquering back or adding extra wort to the boil at a later point like extraction rates from the hops or boiling of the nasties?

 

[wilsoa1111]

i frequently add wort to my boiler in its first 15mins of boiling if i think its a bit low or find some wort in the deadspace, i also tend to do it when i think my eff will suffer and want some extra sparging so have a pan or two on the hob boiling at the same time...

 

[calumscott]

Do you BIAB or extract Andy?

Either way you should be fine. First wort hops disrupt the foam nicely helping prevent boilover. If BIAB, just mash to nearly the top and sparge your bag into a bucket with whatever you need to bring it back up to safe boiling level.

With close attention I think you'll be fine.

 

[WelshPaul]

i frequently add wort to my boiler in its first 15mins of boiling if i think its a bit low or find some wort in the deadspace, i also tend to do it when i think my eff will suffer and want some extra sparging so have a pan or two on the hob boiling at the same time...

Me too. My mash tun always manages to yield an extra litre or so if I leave it to slowly settle 30 minutes or so after the sparge.

 

[Andyhull]

Do you BIAB or extract Andy?

Either way you should be fine. First wort hops disrupt the foam nicely helping prevent boilover. If BIAB, just mash to nearly the top and sparge your bag into a bucket with whatever you need to bring it back up to safe boiling level.

With close attention I think you'll be fine.

Not actually AG brewed yet Callum, but looking into what/how i need to do it and i wil be doing full mash.
I have as stated a 30+ litre boiler and want to do 40pint brews so was just looking into which way would get best/safest use out of my boiler.

Possibly only doing a 60min mash would help reduce the boil off and let me start with a reduced pre boil amount!

Andy