Winterizing the Black Tank flush

[wileecoyote985]

I know I've seen this mentioned here before, but this could save someone some problems down the road.

I did a final check of the Monty last night, before the really cold weather sets in here in Michigan. I looked inside the main storage compartment on my rig to eyeball the visible water lines, to make sure that the RV antifreeze was showing in each. I was able to see three lines, two of which were full of pink (that's a good thing). the remaining line was full of plain water. I managed to trace it back to the black tank flush.

Lacking a pump to pump antifreeze into the flush inlet, I opened the black tank dump valve and removed the dump cover (to prevent any pressure build up in the holding tank) and applied 40 PSI to the fitting after removing the washer and screen. I was able to blow nearly all the water (only a few drops visible) out of the line.

What I don't understand it that the flush inlet is located On the outside wall adjacent to where the toilet is located. While I haven't taken the belly panels off, I would assume that the inlet location would be very near the black water tank also. Makes me wonder why the flush supply line runs all the way to the other side of the rig, before apparently being re-routed to the black tank.

Anyhow, just a heads up for those of you who may have a rig with similar plumbing. I know that at least one person said they didn't bother with this and haven't had a problem. That may be due to the ability of the Pex tubing they are using now to expand without rupturing. Personally I'm not going to risk it.

Gary

p.s.
I also took the screen off the city water inlet and pressed the back flow preventer "button". Was surprised at how much clear water drained back from that too.

[jpbcny]

You can buy a shur-flo drill pump at Home Depot for under $ 7.00, with hose threads on the inlet, and outlet sides, you can make-up a couple of short hoses to pump the anti-freeze through the City Water inlet, and your Black Tank flush line. I don't have the flush line on my 2006 Mountaineer, but I had it on my previous 5er, and this method works quite well.

P.S. I also use compressed air to purge the lines before adding the anti-freeze. It is amazing to see the amount of water in the system even after draining all the lines using the low point drains, and opening all the faucets.

[wileecoyote985]

Thanks JP. No Home Depot here in Stump Junction USA, but we do have a Menards about 50 miles away. I'll check to see if they have the sure flow pump on my next trip to the "Big City" LOL.

[Karl]

Our winterizing procedure is a combination of "blowing" out the lines, then pumping a small amount of RV antifreeze through and dump a little in each trap. Then I just blow out the black water flush without sending the antifreeze through.

You can by the "blowout" adapter for a couple bucks at any RV dealer and at most Walmarts with an RV section

[Wordsmith]

This has been a concern to me since as I read a post a few weeks back about this and am winterizing next week after our last trip of the season. Though I have not used the black tank flush, I am unsure if the previous owner did, so I need to explore this further. Is the only way to purge the line of water to blow it out?

[Karl]

The other way is to somehow pump or push antifreeze into the line from the outside connection...one way is to use one of the little plastic hand pumps like I used to use to push antifreeze through the lines of my older campers...or as was stated in one of the posts above...use a little pump that connects to an electric drill to pump the antifreeze through.

All that said...you "probably" will have no problem if you just leave it as is. There is an anti-siphon/vacuum breaker installed under the sink in the line between the outside flush connection and the black tank. Since that relieves the pressure...the expanding water as it freezes has a place to "go". The combination of a fairly flexible water line and the relief of the pressure by the vacuum breaker will "probably" leave it all ok. (probably is the operative word) I had forgotten to purge the flush line the first winter I had this unit, and I had fogotten on my last travel trailer....and even in Wisconsin's -20 winter temps, I had no problem.

Sorry I go so wordy!

[ken]

we also blew out the lines and then added antifreeze for winter. I blew out the flush line as everyone else did and then with a large syringe that I had gotten from a vet, I squirted about 5 syringes of antifreeze in the line. None came back so I guess it is OK. Have done this same thing for years on our other Montana. Hope this method helps someone.

[sreigle]

If you use the blowout adapter, be sure to limit the air pressure you put through it or you can damage the checkvalve in the city water inlet. Been there. After that I limited it to 40 psi when I was still blowing out the lines.

As for location of the black tank flush, I never really thought about that. I would guess it is both for convenience, being close to the hose connection where it's probably an easy run to the water bib, and at a point where you see it often enough to remind you to flush the tank. If not intended that way, it seems to work for me on both counts.

[kdeiss]

I was told the black flush is self draining no need to blow out