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When to adjust Evap Rate in BIABicus?

Post #1 made 11 years ago
by bundy
Guys I am only a few brews in but already I am seeing a trend that my boil off rate seems to be a fair bit lower than what BIABicus calculates for me.

Obviously plenty of variables, including weather, location etc. But I am thinking the biggest factor affecting my evaporation rate is the Power input when I am boiling.

I use a 40L electric Urn with a 2.4kw element. I have searched back on the forum when PP was getting data for Boil off rates back in 2010. People were posting evap rates of 3.1 - 3.5L per hour with Electric Urns and up to 7 litres an hour with Propane. http://www.biabrewer.info/viewtopic.php?f=51&t=1102

As it stands BIABicus is estimating a boil off rate of around 7.4 litres over 90 minutes for me or approx 4.9 litres per hour.

Seeing (and I know I only have limited input data) am not reaching those rates, and others with Electric Urns have already reported similar evap rates to what I am currently getting, should I now be looking to adjust the calculator to better suit my equipment?

In my mind although temp, humidity etc will all change the evaporation rate, the Power or energy going into my boil is a constant and will never change. Thus I cant boil off faster than the energy being input.

Thoughts?
Last edited by bundy on 29 Apr 2014, 07:27, edited 1 time in total.
    • SVA Brewer With Over 50 Brews From Australia

Post #2 made 11 years ago
by mally
We have the same boiler Bundy.
It would be wrong for me to suggest what to set your boil off rate to, however, I do set my evaporation rate in Section X lower than the auto-estimate.

For reference, I brew in my garage, so I do not have variances with how windy it is, I only have to consider ambient temp & humidity.
That said I find around the 3.5 L/Hr matches fairly well.
:luck:
G B
I spent lots of money on booze, birds and fast cars. The rest I squandered
I've stopped drinking, but only when I'm asleep
I ONCE gave up women and alcohol - it was the worst 20 minutes of my life
    • SVA Brewer With Over 100 Brews From Great Britain

Post #3 made 11 years ago
by bundy
Hi Mally, Thanks for the reply. Yes we both use the Buffalo urn and although you are on the other side of the world it seems our Evaporation rates are very similar (from the limitted data I have for mine anyway) I also brew in my Garage so besides temp and Humidity our other variables are the same.

I know I have very few brews to act as a guide but I am only getting evaporation of around 3.6 litres per hour as well. So over 90 minutes I get 5.4 litres evaporation loss, when my estimate shows 7.4. Thats 2 litres of extra water I shouldn't have in my Kettle.

Today for example I was fairly close on my GIK - Gravity into Kettle but due to a low evap rate in my urn my EOBG ended up a fair way out as I obviously have more liquid still in the Urn than expected.

As everyone says I still have "beer" but I certainly would like to get a bit closer to the estimates.

I dont think I need to adjust anything else just yet but to me this is something that is really standing out as an issue for my setup.
    • SVA Brewer With Over 50 Brews From Australia

Post #4 made 11 years ago
by mally
The normal recommendation for making BIABacus adjustments is around 5 brews in, but to be honest, nobody can stop you from making your own adjustments when and how you feel like!
It seems to me that you are well informed & are aware of the potential pitfalls of doing so.

If you do change it to 3.5 (ish) and you then end up with a higher evaporation you will have less beer, but at a higher gravity (which may also change kettle efficiency, and hop utilisation by the way), but as you are aware of that, then it may be no problem for you.
G B
I spent lots of money on booze, birds and fast cars. The rest I squandered
I've stopped drinking, but only when I'm asleep
I ONCE gave up women and alcohol - it was the worst 20 minutes of my life
    • SVA Brewer With Over 100 Brews From Great Britain

Post #5 made 11 years ago
by PistolPatch
Yep, the evaporation rate on urns does seem to be less than the formula predicts. I think evaporation is safe to change early in the piece as long as the user realises that it will vary from brew to brew. As mally says bundy, you are good to go ;).
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    • SVA Brewer With Over 100 Brews From Australia

Post #6 made 11 years ago
by mally
Oh, and happy birthday Bundy by the way :drink:
G B
I spent lots of money on booze, birds and fast cars. The rest I squandered
I've stopped drinking, but only when I'm asleep
I ONCE gave up women and alcohol - it was the worst 20 minutes of my life
    • SVA Brewer With Over 100 Brews From Great Britain
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