Need an Arc!

[bcmorr]

I will be spending that $5 on antifreeze now just for that. Thanks for sharing I have learned something; glad they figured things out and you can move ahead from here now.

[Jmooney]

The knife valve is the part that opens when you pull the drain handle. It's like a flat paddle that slides in/out of the round pipe and opens or closes. It's at the end of the pipe that empties the tank, in my case the grey water tank.

Because I didn't fully drain all water from the grey tank, once I closed the valve ( pushed in the handle ), some water built up behind it in the drain pipe, and froze, splitting the junction.

What I didn't do properly:

Drain both grey and black tanks..... Completely ( they can slow trickle for a long time )

pour RV antifreeze down both sink and toilet, to feed both grey and black tanks. the antifreeze will flow through the tank and down the drain pipe. Slightly open the knife valve and you should see the pink antifreeze begin to drain.

Close it up.

[Ela1948]

I know exactly what you are saying. I have dumped the tanks and left the valves open for an extended period of time. Closed them an hour later and found that they were frozen in place after the temperature dropped. The tanks can drip water for a LONG, LONG time after dumping. I never had enough water left to cause damage. But it's easy to see how your problem could happen. Most education comes with a price. Unfortunately it was your turn up to the plate. Thanks for letting the rest of us have the chance to learn from your misfortune!!!

[lovinglife]

Thanks so much for your explicit descriptions. DH says he very clearly understands what you are referring to, and didn't realize it was called a knife valve. It does make perfect sense, and as others have said, I'm sorry for your troubles in this lesson for all of us, and we appreciate your information. DH does say that it does appear that you followed the manufacturer's instructions, and wonders if this is a bit of a design flaw on their part...

In any case, I'm glad that you will soon have your unit back, and can complete your plans and enjoy your rig. I appreciate your sharing with us.