Rogermort
Regular.
is your hlt under temp control? if so how long was it stood at temp waiting, there is a feature of temp controlled hlt's that results in the target temp being maintained at the point of the temperature probe, BUT the liqour can 'stratify' into layers which are cooler below the temp probe and warmer above.. this can be easily rectified by giving the hlt liquor a damn good stir before sparging, some lazier brewers have been known to add recirculation pumps or motorised paddles to keep the liquor moving and ensuring a consistent temperature throughout the liquor..
when i noticed this the liquor i was initially drawing off for spargeing was a good 10C lower than the target temp!! My hlt had been stood @ temp for some time tho...
if your hlt was full to capacity and your sparge left a significant volume behind this may explain a less than spectacular efficiency leaving sugars behind in the grain due to too cool a sparge??
Yes the HLT is controlled by a (mildly inaccurate) controller so I take regular readings using my Thermapen. However, you are correct in that yesterday I didn't swirl the water around regularly. Couple that with the fact that as already mentioned, I was concentrating so hard on slowing the sparge down that I probably lost some temperature between HLT and Mash Tun. I have a ball valve on the HLT and another on the outlet side of the pump. Having the first one full open and controlling the flow with second would allow cooling in the silicon tubing between the HLT and the pump.
I sparged the volume that BeerSmith suggested (and only left around eight litres in the HLT) but I may have been sparging with water that had dropped below the 75.6C I'd intended.
