I use a tempering tank because my boiler DHW coil is not up to the task of producing enough GPM - When I use it gently to temper the cold side water that I introduce to the thermo reacting valve - it provides sufficient volume on the hot side, to bring the supply to code set temperature for significantly more use at the desired GPM output.
This month I installed a used working 50 gallon electric DHW heater before and in series with a 4O NG fired tank to provide a couple kids with enough water to fill their big bubble tub. I turned the resistance heaters down to about 105 and wired a used magnetic switch to turn the appliance on and off remotely-- They simply plan to use the tub -- heat the temper tank for a few hours - and turn it off before filling the tub.
All from used and cheep parts
