I'll soon be adding a HERMS-loop to my brewery. And I can't find a suitable container very easily. But I came across a toiletbrush(!) from IKEA which has a nice cylindrical container and holds about 4 litres. I'll be adding a copper coil (copper to get the best heat exchange) which is 5 meters and 8mm OD, I guess it's about 6mm ID. I'll heat it with a 3kW camco element. Calculators online say that it will take the temp from 55C to 66C in between a minute and two.
The pump which will serve this thing is one of those 12V ebay-pumps from china. It can pump 600L per hour. I guess this is when nothing is connected to it, so the flow will be somewhat smaller since ill be adding some height and the coil is about 6mm ID which will give it resitance. I'll also add a power adapter which is switchable between 7.5, 9 and 12v, instead of choking the flow of the non-magnetic-impeller-pump.
I guess I can't go totally wrong with this, but is there anything I could do which would improve the systems response-time?