Two questions? Starting with the OP. I cured myself of the sparging necessity a while ago as not sparging offered me some useful shortcuts. A lot of people here are giving a thumbs up to "no sparge" but haven't let go of some nonsense connected to it. There is only one very good reason to sparge … you don't have a vessel big enough to hold all the grain and sufficient water to get a full pre-boil run length, but even then you can add a litre or two of plain (cold probably) top up water. So:
Nonsense 1: It will result in lower extract. Just do the sums. W-e-l-l …. I did for this post and the results didn't back me up! The sums suggested I'd need to add about 12% more grain to counter the loss of extract due to "no-sparge". This didn't reflect my experiences so I had to look for other reasons. Firstly the result is going to be subjective: I reckon you need 12% extra, the BYO article
@foxy linked suggests 20-25% more. But however carefully you calculate your sparge water volume, chances are you close the tap before all the sparge water is drained 'cos you've collected enough. In the past I've found if I drain the remaining sparge water from the mash later it has a gravity much closer to OG than the final runoff (which was probably around 1.010). So some extract is "hiding" from the sparge rinse until gravity forces it out (suggests "batch sparging" is not low efficiency compared to "fly sparge", and therefore "no-sparge" need not be lower efficiency either). So I reckon you only need allow for 5-6% extra grain to off-set "no-sparge" losses, if that, and perhaps sharpen up the water calculations and allow to drain a bit longer (I do the latter when using a Grainfather which encourages more through draining - I use the GF exclusively in "no-sparge" mode).
Nonsense 2: The enzymes get diluted and less efficient in the higher water to grain ratios of "no-sparge". Certainly not what I've experienced, though I must admit I always use mash recirculation systems (either a 3V HERMS setup or a Grainfather which is a glorified RIMS setup). The enzymes are very soluble in water so the recirculation probably massively increases the chances of enzymes bumping into their target molecules (starches and dextrins) so the extra dilution is rendered immaterial.
And the second question by
@Charles Stanley-Grey. Temperature too hot. Of course "no-sparge" avoids the paranoia of sparging too hot. Mashing "too" hot might well produce a higher proportion of unfermentable sugar. But this might be done on purpose! High residual (unfermentable) sugar is a feature of some beers, especially some British beers. "No-sparge" reduces the risk of mashing too hot because larger quantities of water are used and the "strike" temperature is very much lower. But this brings me onto another "nonsense":
Nonsense 3. Too hot a temperature (mash or sparge) extracts undesirable astringency. Well it can, but it isn't something to get too concerned about. As has already been mentioned, it's not really the temperature it's the pH, and too high a pH is probably the result of over sparging with high pH water. Cure: "No-sparge" or acidify the sparge water (to about pH5.4-5.5). The other nonsense in this is a lot of people can't distinguish between being too heavy handed with hops (bitter) and extracting too much polyphenols like "tannin" (astringent): Clue, you
taste bitterness, you
feel astringency. Result: These people know they have a problem, but they go looking for it in completely the wrong place!
Whoa, there's a rant. I must be having a bad day?