Water drain & tank flushing question

I've been digging through the documents for our new 2552 and have 2 questions (for now).  Where is the drain for the fresh water tank?  And...  I want to learn how to flush the tanks.  I've emptied both of them - no problems there.  But to flush the tanks...  How do I know how much water to add?  I assume I have to leave the drain in the septic tank?  I don't want the anything to back up into my new PC. 

Thanks!
Peg

Peg,

I believe the fresh water tank drain is located the same place as it is on our 3100, which is under the passenger side bed.  To access it, lift the mattress up and remove the square wood panel located near the head of the bed.  You will probably need a flat-blade screwdriver to lift up the wood panel.  Then, if you look down in the hole you will see a water shutoff valve that you turn one-quarter turn to drain the tank.  Be prepared to wait, as Phoenix had filled our tank full when we picked it up and it doesn't drain very fast.  You didn't ask, but to drain the water heater, you need to open the panel on the outside of the RV and remove the hex plug at the bottom of the tank.  It easiest if you use a socket and an extension to remove it.  Then, open the pressure release valve located near the top of the tank and the water will drain quickly.

When you flush the holding tanks, just connect your hose to the hose fitting located in the compartment that has the tank drain controls on the driver's side of the unit.  There are two silver valves located near the hose fitting, one for the black tank and one for the gray tank.  You open one at a time if you want the most pressure or both if you want lesser pressure for the cleaning process.  When you do this, some people have the tank drain valves open during the entire process and others leave them closed for a few minutes and then open them to get a better flow of water out of the tanks.  I usually leave them closed until the tank has been flushed for 5 to 7 minutes and then open the drain.  I don't wait any longer because as you indicated, you don't want to over fill the tank.

If you have any more questions, feel free to ask if my instructions aren't clear.

Gary

I believe the waste tank flushing sprayers are mounted into the side of the tank, not the top.  If you close the tank valve and start spraying, when you stop hearing the water splashing, that is a good time to open the main 3" gravity drain and let everything rush out while still spraying.

Because our rig is stored in our garage below our bedroom, we cannot tolerate any kind of sewer gas.  So I add an extra process.  Once flushed, I add some bleach and fill each tank again to their tippy-top, let it sit for an hour, then open the 3" drain cap and valves and let the rush of bleach solution exit quickly for a good flushing.  Then repeat with fresh water to get all the bleach out.  I understand bleach sitting inside any of the systems for a long time can be hard on the mechanical things and gaskets.

There should be an access panel on the bed board. Lift the passenger side mattress to find the cut out. Ours is less than a foot square. No screws but a screwdriver might help you lift the cut out piece. You do not have to remove the entire bed board. This access port lets you reach the little valve on the side of your fresh water tank that opens the drain. It just poured out under the rig. Remember to close it again. You can also access the valve for your water pump and there should be a plastic tube attached to the pump that you can lift out and put in your antifreeze bottle for winterizing. When you turn the valve, you pump draws from that tube.

As a precaution, I put a backflow preventer on the tank flush hose, and always make sure the faucet is on with water pressure in the hose before opening a flush valve.