Thank you! The tank stays about same temp as boiler, now 140-150. I haven't run out of hot water yet
I keep Rinnai tankless water heater on also in house set at 120. The tempered water coming in goes to cold inlet of tankless water heater at around 130 so Rinnai never fires up.
. I ran 3/4 cooper from 1 inlet of coil to drain of HW tank, and the outlet of coil up to PRV valve of hot water. I put dielect union on both coil inlet,outlet and on both ends of water tank for easy removal.I have 2 PRV on inlet of coil and on top of tank where prv valve went into tank. Gooday! Joe