Not sure if you are familiar with OpenStudioApp, but in it, you can go the Thermal Zones tab, then create a thermal zone (or use an existing one, if your model already has such) and then from Library on the right-hand side drag a Heat Pump Water Heater from the Water Heater - Heat Pump drop-down into the Zone Equipment field of the thermal zone.
Then you can click on that and in Edit on the right-hand side you can adjust its parameters.
Further, in Edit on the right-hand side, there is a small tab near the top that looks like chain links, next to the tab that looks like a gear. In that "links" tab, you can checkbox a preexisting service hot water loop to link your new heat pump water heater to. That way you can make it available to a Water Use Connection. However your water heater will not show up in the service hot water loop as that heat pump water heater, but rather as the tank that was created automatically when you dragged your heat pump water heater to Zone Equipment.
From there onward it should all be standard water heating stuff to complete your model. Good luck.
