Anyhow, as for the cost of the boil, it may be worth considering the value too.
I'm inclined to follow this guys advice of a vigorous boil for 60+ minutes.
This was certainly an interesting listen
.
I do wonder how the difference in scale between home brewers and commercial breweries impacts the effects of the boil. A lot of the cited research (including Dr Bamforth's) is naturally for commercial breweries (as they can afford to fund the studies). A rolling/vigourous boil in a 15 barrel kettle is going to be quite different to a 5 gallon kettle, which will naturally affect wort agitation (protein coagulation) and DMS boil-off.
Crisps list the same things that Dr Bamforth does of importance in the boil (vigour, rate of energy, duration) but then says this is "essentially the evaporation rate". Commercial guidance for boiloff (evaporation) rate varies, but generally 3-7% from a random selection of internet pages (Crisps say at least 6% evaporation for an hour, O'Rourke says 4-12%). I have a feeling that homebrewers have read 'vigourous' and been boiling at unnecessarily high rates because that's what the research has said. Looking at some of the photos of gas-powered homebrewers with their
monster burners I can fully expect that the relative (to vessel size/dimension) boil power of home brewers is much larger than commercial breweries. A quick search on the forums has people saying/recommending a boil-off of 10-15% with some brewers stating as high as 20% boiloff.
Looking at my own (normal, before my original post that created so much hate
) stats, my pre-boil volume was 28l, with 3l of boil-off. That's 10.7%. I didn't take a reading from my reduced-power boil but even if it dropped down to 2l, that would 7%, which is in-line with commercial brewery recommendations. So my 'reduced power' boil (not a simmer, it still had plenty of bubbles breaching the surface, just not a volcano) is probably actually in line with the guidance offered by Dr Bamforth, O'Rourke etc.
I wonder whether this is why so many home-brewers (including
Brulosophy) don't get DMS in their beers - the home-brew boil is sufficiently powerful (even at what seems to be a 'timid' boil) to drive off DMS and achieve the required hot break.