I am looking to install a mixing valve on our current water heater so I can increse the temperature to 140 to 150 and not be scalded. I was looking at the Honeywell AMX300 mixing valve that attaches directly to the top of the water heater.

The specs list the minimum flow rate as 0.25 gpm. My question is what will happen if you open a hot faucet just a trickle and have a flow rate less than 0.25 gpm? Will you get scalded with 140 or 150 deg water? Or is the mixing valve just not quite as accurate below 0.25 gpm?