Checked online, but the first entries were for gall bladder, liver and kidney tests related to a HIDA test.Supposedly it helps find microcracks in the heat exchanger.
if this is a residential furnace hydroscan is not necessary. there are more accurate ways to test the heat exchanger. there is a smoke bomb test. there is a draft test over the fire before and after the blower runs. these are the old standby test that the industry uses
Hydro scan test is water to see if there is the right moisture in the air.
