Help with Brewfather figures please

[Tractorboy]

I have purchased an all grain kit from Malt Miller for a Verdant Lightbulb Extra Pale Ale.
The kit does not provide any water quantities, which I expect is due to different methods and efficiencies that could be used, so I have tried putting the ingredients into Brewfather to work out how much mash and sparge water to use for each stage.

The description of the beer says that it should be around 4.5%, however, when I put the figures into Brewfather, it comes out at 6.8% based on a 20l batch.

I brew using a 30l BrewDevil, so I have used the Brewster Beacon profile in Brewfather as it seems a very similar piece of kit.

The kit total is 5.36kg of fermentables and gives me a pre boil volume of 24.64 L:

SIMPSONS MALTS PROPINO EXTRA PALE MALT (2700 grams)
Weyermann Vienna Malt (800 grams)
Flaked Oats Including Husk (1500 grams)
Weyermann Carapils (180 grams)
Crisp CaraGold Malt (180 grams)

In the description the OG is stated as 1.045, but in Brewfather it comes out for me at 1.065

Efficiencies in the profile are:

Brewhouse Efficiency 79.4%
Mash Efficiency 80.2%

Is there something that I have missed that makes my calculated figures so far off?

Thank you.

 

[Session]

I would start by scaling your brew house efficiency down to 70% and see what that looks like, after that the profile will be something you continue to tweak each brew to get it closer to your actual numbers. BrewFather is great as it gives you your actual figures as well as your predicted, so you know how to change your equipment profile next time to make it more accurate.

 

[Tractorboy]

To get the calculated ABV down to 4.7% I have to use a brew house efficiency of 55%, which feels a bit low to me.
Would I be best to just make the beer with the ingredients I've got and the calculated water quantities and see how it turns out? It's no problem for me if I have a slightly stronger beer.
I assume that if I know the grain bill and the water quantities used, I can then use my OG to calculate my efficiency?

 

[Gerryjo]

Just brew the kit taking note of all water, boil off pre boil gravity, OG and fermenter amount. From there just backtrack and enter in the amounts and this will give you an accurate benchmark to work off.