I am not able to source a 3way valve here in vallarta. I am trying to add a bypass to the heat pump as it's only used for a couple months. Would it be ok to put 4 shutoff valves before and after connections in and out of heater or would that ristrict water flow when heater is shut out? I could always not put a Bypass as heatsiphon says it's a flow through design and a bypass is not needed. Any suggestions or input. Thanks!