To provide DHW, this type of boiler tends to maintain internal boiler water temperature higher and more consistent than those that do not have this feature. There may be a separate aquastat and possibly a flow sensor. You'd want to fool the boiler to think that the DHW requirements were met so it wouldn't fire in the summer or other times unnecessarily. Also, some of these have a flow restrictor in them to help ensure adequate heat output. You may need to address that if you do what is described in the next paragraph.
You may want to still run the output of this coil to your tank as the cold input if you can't disable the controls. Someone with more understanding of the controls may be able to help decide the best route.
Are you going with an indirect, or a separately fired WH?