De-winterize 279QBL

[GS2012279QBL]

Hello,

We just purchased a 2012 Innsbruck 279QBL. I am not yet familiar with the trailer and the previous owner said it was winterized. I would like to de-winterize the trailer. He noted the hot water heater was bypassed. I have the following questions:

1) What is the method to drain/flush the RV antifreeze?
2) Is there a hose I need to remove and / or attach to the water pump?
3) Do I add water to tank prior to draining coolant?
4) If trailer has not been used for 3 years, do I need to treat water tank with bleach?
5) Is there anything else other than bleach that is used?


Thanks in advance for any insights.