Draining water tank

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cougsfan

Member
Joined
Aug 2, 2009
Posts
21
Location
Eastern Washington
I have a 1998 WF331WM that I bought last fall.  The previous owner stored it in a heated shop and never had to winterize it, and didn't even know how to.  I am not so lucky.  I used it once last fall before winterizing.  I didn't use the water storage tank, and it was already empty, so all I had to do was drain the water heater and blow out all the lines with air to winterize the water system.  This year I did use the fresh water storage tank.  I am ready to winterize it and I can't figure out how to drain the fresh water tank.  The Owner's Manual (which covers umpteen different units) says; "drain the water tank", and that is about the sum of it.  The tank is at the rear of the unit under the bed.  Their are 4 valves beside the tank; two look like ball valves, one is a 3 way valve (for sucking antifreeze in, I think) and the last one is a 180 degree valve on the same line as the three way valve.  None of these valves drain the tank. I have tried all sorts of combinations of valve settings. (I can't see where any of these valves do anything. I thought they may be isolation valves to shut water off to different parts of the Motor home, but they don't even seem to do that)  I crawled all over under the unit looking for a water tank drain valve, but can't find one.
Can anyone tell me the secret for such a basic task?
 

cbeierl

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Joined
Jan 12, 2007
Posts
646
Location
Nashua, NH
Here's the plumbing diagram for your coach: WF331WM.  Unfortunately, it's not as helpful or easy to read as the more recent ones  :( .  I couldn't immediately identify the fresh water drain.  You may need to zoom into the diagram quite a bit to see some of the details--perhaps you can match up the diagram with the plumbing you find in your coach.
 

Mavarick

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Joined
Jan 30, 2011
Posts
2,027
Coug, don't limit yourself to just the spots that seem obvious around the water bay. Mine is dumped by cable so the actual drain is in the 2nd bay on the passenger side no where near my water bay which is in the left rear bay. The drain handle is tucked away up high on the left side of the bay, not very easy to notice. It is a small T-handle on a cable. Good luck.
 

cougsfan

Member
Joined
Aug 2, 2009
Posts
21
Location
Eastern Washington
Thanks Chris, I am not sure the diagram shows me how to drain the tank, and it is rather hard to understand, but it does help me understand the plumbing much better.  I suspect those two valves I didn't know they are for are to isolate the outside faucet.  I will check that out tomorrow.    The other two valves appear to be on the suction of the pump.  One isolates the pump from the tank and other allows you to suck antifreeze into the pump.  It is frustrating because it is impossible to tell if these valves are open or closed by looking at them, but now I know they should starve the pump if they are closed.

I will look elsewhere for drain valves like Maverick suggests.  I don't see any drain lines out of the tank anywhere, only a line to the pump suction.  There are some more valves under a panel door in the floor under the bathroom sink, and some more valves by the hot water heater (behind a drawer under the fridge) They are not shown on the schematic, but one may be a drain.  Any drain in the plumbing down stream of the pump would mean that you have to pump the tank empty.  Is that common? If that is the case, I could just pump it all out through a faucet into to a holding tank just as easily.  Again I am leery of flipping valves because I don't know what the valves do, if I am opening or closing a particular valve, or what position it even should be in.  Guess I will just have to experiment.

Would sure be nice if Winnebago would have labeled valves, flow directions, etc, at access points.  I think I will if I ever figure it out.
 

winnie32v

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Joined
Mar 17, 2012
Posts
182
I would suggest that you call Winnebago customer service and see if they can pin-point the valve for you.
They are extremely helpful.

800-537-1885

Please let us know how you make out.

Regards.
Paul
 

Gary RV_Wizard

Site Team
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Feb 2, 2005
Posts
73,979
Location
At our Silver Springs FL home
Some systems do indeed use the pump to drain water thriugh valves that are downstream from it.

Your water system should include two low point drains - valves in the lowest part of the hot and cold lines, used to drain water from the lines themselves. In some designs, these valves are also the means of draining the tank. The valves you found below the floor may be the low point drains - they would let water exit underneath the RV.

I have also seen systems where the "drain" was simply a screw-on cap on a line that exits under the tank - no actual valve. That was fairly common back in the 80's and 90's.
 

SVTotem

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Jul 29, 2010
Posts
199
Location
Orlando, FL
You might have done this, so forgive me.

After trying all that you listed I would crawl under the unit and look for the drain pipe. It is most likely going to extend below the flooring, but perhaps not beneath the frame members. If you can locate this point in the system you might be able to trace back to the most likely location for the valve. It is quite possible that you have a gravity feed drain right from the bottom of the tank and the valve may be visible with a cable run to it or an access plate nearby to reach the valve from inside.

Good luck, and let us know where you finally found it.

 

Jeff Brown

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Joined
Feb 23, 2010
Posts
717
Location
So Cal
My 93 Pinnacle had the drain inline under the rig directly under the tank and the tank was where you are discribing under the rear queen bed.  There was no good way to drain it.  But 2 things were certain, you were going to get dirty and you were going to get wet.

Good Luck

Jeff
 

cougsfan

Member
Joined
Aug 2, 2009
Posts
21
Location
Eastern Washington
I did find a drain valve up under the bathroom sink and pumped all the water from the tank out the drain onto the ground.  I also figured out that the both valves on the pump suction are 3 way valves.    One is to feed antifreeze to the pump and the other is a drain with a short drain line coming out under the incoming power cord box.  However, it doesn't drain.  In what you would think is the drain position it will suck air in through the hose if the pump is on but won't drain out if the pump is off (???)  It is like there is a check valve in it.

I blew everything out with lots and lots of air and I am sure it is all empty except I am not sure the the pump area got completely drained. so I sucked a bunch of RV antifreeze into the pump just to be sure.  Feel like it is all OK for the winter.  Thanks for all the help.

By the way, I would also normally say that the way the handle points is the direction of flow, but I can assure you that is not the case with these valves.  I drew a sketch and made notes to save what I learned because I will forget by next year and it all defies common sense a bit.
 

winnie32v

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Joined
Mar 17, 2012
Posts
182
Just a couple of points that may have been forgotten:
Ensure that you OPENED ALL VALVES (kitchen, bath, shower, toilet  AND outside shower) so that all water has an opportunity to gravity flow to your drain point.
Be sure your toilet valve is winterized.
Don't forget to winterize the outside shower.
And, add some excess antifreeze to all traps, don't forget the shower trap.
Allow excess antifreeze to enter the gray & black tanks. (Drain of all water first)

Remove your drain plug from the WH and use a small hose to siphon excess water from the bottom of the tank. 
I did mine yesterday and removed about 2 pints from it.
Some put a little extra antifreeze in the tank...I don't in this case.

Hope this helps.
Regards.
Paul
 
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