a mate of mine came up with a couple of good ideas (in the pub as usual!)to solve the problem of matching flows when sparging.
He suggested using a 3 tier system and that, as the out flow of the mash tun will drop into the boiler by gravity, and that the sparge water from the HLT is also draining into the mash tun by gravity, why not fit a calibrated restriction in the out flow of the HLT by way of a washer with a 1mm hole in it for example(calibrated at around 500ml per minute with half the sparge water remaining in the HLT) so flow into the sparge arm is always around 500ml a minute(a little faster at the start of the sparge and a little slower at the end of the sparge due to the head dropping)? All one would need to do is turn the flow valve on and leave it.
His second idea is to use a clear (wide)flexible pipe from the outlet from the mash tun running up the outside of the tun then looping back down to the boiler, the hight of the top of this loop is then easily adjusted to match the top of the wort whilst your waiting for the mash period to expire. You then turn the valve on from the HLT and as the sparge water flows at a set rate into the sparge arm, the wort level rises and it flows over the loop and runs into the boiler!
I thought this was a great idea! Once setup the system would run itself, no pumps or valves to fiddle with until the Boiler has sufficient wort to stop sparging!
What do you guys think?
steve