Aqua Hot 450D troubleshooting cool air zone 2 (front)

You have 3 pumps. It is very hard to "hear" a pump running. I usually put my hand on the pump to feel if it is running. I also feel the return lines coming in the top of the Aqua Hot and the lines should be as hot as the lines coming out of the pumps. I am not sure from your post if you did that. IF the return lines are all hot, then the coolant IS flowing thru the radiators. Do the radiator muffin fans come on? Are you using the Diesel burner to get the tank hot? Doug