When I do a complete flush with water from the house, I pull the bottom hose off to get as much water out as I can. Then I refill the system with distilled water, run the engine till the thermostat opens, let the engine cool and drain and refill with distilled water, run the engine again. Once all the water is drained add the coolant, even with the water in the block you should be at 40% concentration of coolant to water. Don't use the prediluted coolant. The reason I do it that way is to get the minerals out of the system especially if the water is real hard.
1999 35 ft. Dolphin 5350, F53, Banks System, 5 Stars Tune, Air Lift Air Bags, Koni Shocks, Blue OX TruCenter, TigerTrak track bars F&R, Roadmaster 1-3/4" rear auxiliary sway bar, 2004 F450 Lariat Pickup 6.0 Diesel Crew Cab DRW, 4X4, GVWR 15,000, Front GAWR 6,000, Rear GAWR 11,000, GCWR 26,000,1994 36ft Avion 5er, GVWR 13,700, 2,740 Pin Weight.