Is anyone out there using a Garn WHS as an add-on to an existing forced air system? I'm trying to get a rough idea of what additional equipment and parts (not included with the Garn unit) would be required. I'm not looking for an exact installation design, just the major components, so I can include them in the cost estimate. So far, I've figured the following... Underground PEX piping Circulation pump(s) Water-to-air HX for air duct Aquastat(s) Are any major components missing from my list? Obviously there needs to be some integration with the existing controls. Any recommendations? Thanks!