The TD3030's are a complete nightmare. If it isn't the blower (E05 error) then it is the temp input thermistor (E17 error). And then there is the E14 gas valve errors. And the E15 errors when you forget to clean the secondary lint screens. Then there is the E99 general failure error. I have the first of the first of these. When they work, they are phenomenal, but look at them wrong and they will blow an error.
The extra valve is on the larger capacity machines to assist with the fill (it can be long with just the 2 valves) and to flush sticky, gooey additives into the machine and keep the dispenser box clean. This is the way it is on the Gen 5 and 6 machines; the Gen 4 setup may be different -- the center valve with the 3 solenoids are for the soapbox. Connect this to hot to keep the box a bit more fresh.
I was looking at the drain. Is it the motorized one or the pancake/Berkert water solenoid one? Looks like the motorized one to me; I didn't see a Berkert solenoid up near the water valves.