Heat Timer ETV Mixing valve

boiler_man

Hi, I have to replace a current Watts 2 inch domestic hot water tempering valve with a new valve and would like to install a Heat Timer ETV. I have contacted Heat Timer but could not get any useful assistance as to sizing my ETV properly. They insist that I give them the flow rate but I don't have the means to figure that out but Here's what I know. Tankless coil is rated for 1200 GPH. Currently the supply to the watts mixing valve are 2 inch openings for hot water entering the valve and for the tempered water leaving the valve. pressure before the coil is about 50 and after the coil its also about 50-51. building located in nyc, 60 apartments each with 1 bath, 2 sinks, some with a washing machine.



I had previously spoken to heat timer and the gentleman said he could verify the correct sizing if I gave him the pressure difference before and after the coil. I have it - 2 PSI. But when I called today a different individual told me that I had to know what the flow is....  Please Help (I need this for tomorrow.) Thanks.