Winterizing toilet flush line

[Rayray04]

Hey guys I have a 2019 keystone cougar 369BHS,, how do you winterize the black tank flush line

[Canonman]

I just use a little compressed air. 40 psi
I use the same blow out tool as I do for the city water input. They are cheap enough I have a separate one for the FW as well as the black tank flush.
https://www.amazon.com/Camco-36153-B...35320602&psc=1

[JRTJH]

I blow mine out with low pressure compressed air (about 40PSI) and then remove the anti-siphon valve and after it's completely dry, store it in a ziplock sandwich bag under the vanity.

[ChuckS]

Id remove the anti siphon valve permanently and couple the two lines together with a shark bite union... The siphon valve is a joke and a major source of water damage if not checked often...

If you just gotta have an an anti siphon device on the black tank wash out connection then install a garden hose spigot anti siphon valve on the hose you use to wash out the black tank with...

https://www.amazon.com/Mueller-108-9...52538841&psc=1

[1st Chev Diesel]

I pump antifreeze through the inside water pipes including the outside "shower" blue hose. Then I connect the outside blue hose to the black flush tank faucet and turn on the cold water blue hose tap and antifreeze goes into the black tank flush piping. And thus it is winterized with antifreeze.

[chuckster57]

Originally Posted by 1st Chev Diesel

I pump antifreeze through the inside water pipes including the outside "shower" blue hose. Then I connect the outside blue hose to the black flush tank faucet and turn on the cold water blue hose tap and antifreeze goes into the black tank flush piping. And thus it is winterized with antifreeze.

And if the anti siphon valve is working, the antifreeze solution drains out both lines.

[dutchmensport]

On my previous travel trailer (Outback), I blew the black tank flush. On my current Montana High Country fifth wheel, I connect the black tank port to the out side shower hose, turn on the shower hose and suck the pink until I see pink come out of the black tank outlet.

Of course, I have passed a couple hundred gallons of water through the black tank already flushing it out until it runs completely clean. I do that when winterizing. So, when running the pink, it comes out pink.

[Whitewolf]

Air everywhere. Then dump enough pink in the drains to fill the traps. I also got rid of the anti-siphon valve for the reason ChuckS said.

[jwfrede]

Originally Posted by chuckster57

And if the anti siphon valve is working, the antifreeze solution drains out both lines.

And in that case isn't it just droplets of anti-freeze that are left behind? And everything should be ok for winter cold.

[GMH]

Originally Posted by ChuckS

Id remove the anti siphon valve permanently and couple the two lines together with a shark bite union... The siphon valve is a joke and a major source of water damage if not checked often...

If you just gotta have an an anti siphon device on the black tank wash out connection then install a garden hose spigot anti siphon valve on the hose you use to wash out the black tank with...

https://www.amazon.com/Mueller-108-9...52538841&psc=1

I’m confused. Doesn’t the flusher just spray water into the black tank? How is that connected to the anti siphon valve? I just watched a video on eliminating the asv, and I wonder what purpose the two white water lines up behind the sink serve? Where do they come from and go to? I don’t mean to hijack the thread, but it is all related….I think.

[sourdough]

The 2 white lines coming into that "little arrangement" are fresh water in from the black tank flush port and fresh water out to the black tank rinsers. That picture shows the anti siphon removed and an L put in its place. If that is yours I would be using a hose end anti siphon valve where you screw the black tank flush hose into the flush port.

[GMH]

Originally Posted by sourdough

The 2 white lines coming into that "little arrangement" are fresh water in from the black tank flush port and fresh water out to the black tank rinsers. That picture shows the anti siphon removed and an L put in its place. If that is yours I would be using a hose end anti siphon valve where you screw the black tank flush hose into the flush port.

Not mine. Why isn’t the flush port run directly into the black tank? Please excuse my ignorance.

[flybouy]

Originally Posted by GMH

Not mine. Why isn’t the flush port run directly into the black tank? Please excuse my ignorance.

Simply put, it would be the same as opening the black tank dump valve. The plumbing under the sink is to allow the hose connection to be low enough so that it won't back into the hose connection. The vacuum break or anti-siphon valve is there to prevent the flush hose from siphoning the contents of the black tank.

Let's say you connect your water hose to the flush port with no anti-siphon valve with the black tank full. You turn on the water but forget to open the drain valve. Oops, in a panic you turn off the water and disconnect the hose from the water source. Now, the water and what's behind it will flow out of the hose. Have you ever siphoned gas out of a gas can or car? Same thing.

[GMH]

Ok, I get it. So the guy in the video that I got that screenshot of just defeated that function.

[flybouy]

Originally Posted by GMH

Ok, I get it. So the guy in the video that I got that screenshot of just defeated that function.

Yes they did. But, if you use a anti siphon valve inbetween the supply hose and the rinser inlet on the side of the camper.

[erm626]

Where is the anti siphon valve on most Rv's I might be thinking of a Vacuum vent valve under the kitchen sink... I have never run anti freeze into the Black flush inlet... Is this a future problem ?

[JRTJH]

Originally Posted by erm626

Where is the anti siphon valve on most Rv's I might be thinking of a Vacuum vent valve under the kitchen sink... I have never run anti freeze into the Black flush inlet... Is this a future problem ?

Typically, the anti-siphon valve is located under the bathroom vanity. You'll probably see 4 PEX tubes in the vanity base. Two will be hot/cold water lines to the faucet. The other two will be anti-siphon supply lines. One from the outside trailer wall to the valve and one from the valve to the nozzle in the tank.

The "problem" with not winterizing the black tank flush system is a potential "plug" or "occluded nozzle". If there is an obstruction "dried to or wrapped around the nozzle" it may not drain properly. If that happens, then water can fill the tube from the anti-siphon valve to the nozzle. With water standing in that line, when the temperature falls, ice forms and can damage the nozzle, the fittings/adapters and, if the water is backed up to the anti-siphon valve, ice can damage that valve as well. If that happens, there's a good possibility that the next time you turn on water to the system, you can flood your vanity cabinet.

Here is a photo of my anti-siphon valve in the vanity. Again, if you have 4 PEX lines in the vanity, your anti-siphon valve is there, connected to two of them.

[jimborokz]

Originally Posted by JRTJH

Typically, the anti-siphon valve is located under the bathroom vanity. You'll probably see 4 PEX tubes in the vanity base. Two will be hot/cold water lines to the faucet. The other two will be anti-siphon supply lines. One from the outside trailer wall to the valve and one from the valve to the nozzle in the tank.

The "problem" with not winterizing the black tank flush system is a potential "plug" or "occluded nozzle". If there is an obstruction "dried to or wrapped around the nozzle" it may not drain properly. If that happens, then water can fill the tube from the anti-siphon valve to the nozzle. With water standing in that line, when the temperature falls, ice forms and can damage the nozzle, the fittings/adapters and, if the water is backed up to the anti-siphon valve, ice can damage that valve as well. If that happens, there's a good possibility that the next time you turn on water to the system, you can flood your vanity cabinet.

Here is a photo of my anti-siphon valve in the vanity. Again, if you have 4 PEX lines in the vanity, your anti-siphon valve is there, connected to two of them.

Mine happens to be behind the convenience center. Not sure why but at least if it fails I won't have water all over the bathroom floor, it will all be in the underbelly. Of course I won't know that it's failed quite so soon.
Hmmm, might be time to take some pre-emptive action and change that.

[JRTJH]

Originally Posted by jimborokz

Mine happens to be behind the convenience center. Not sure why but at least if it fails I won't have water all over the bathroom floor, it will all be in the underbelly. Of course I won't know that it's failed quite so soon.
Hmmm, might be time to take some pre-emptive action and change that.

Jim,

As I understand the function of the anti-siphon valve, it "should be" located above the highest component in the black tank system. That component is the rim on the toilet. Theoretically, if the black tank is full and backs up into the toilet, black tank contents will then effectively be "higher than the anti-siphon valve, if it's located "down in the convenience center"...

That's why it's "way up in the top of the vanity" or in some floorplans, "in the wall behind the shower faucet handles"...

If I were you, I'd do some checking to see why your anti-siphon valve is located so low in the black tank system....

That location, at least as I understand the function, isn't providing the protection the anti-siphon valve is designed to provide.

So, is that the way your system was installed by Keystone? Or, is this the way it was "fixed" due to a past problem?

[jimborokz]

Originally Posted by JRTJH

Jim,

As I understand the function of the anti-siphon valve, it "should be" located above the highest component in the black tank system. That component is the rim on the toilet. Theoretically, if the black tank is full and backs up into the toilet, black tank contents will then effectively be "higher than the anti-siphon valve, if it's located "down in the convenience center"...

That's why it's "way up in the top of the vanity" or in some floorplans, "in the wall behind the shower faucet handles"...

If I were you, I'd do some checking to see why your anti-siphon valve is located so low in the black tank system....

That location, at least as I understand the function, isn't providing the protection the anti-siphon valve is designed to provide.

So, is that the way your system was installed by Keystone? Or, is this the way it was "fixed" due to a past problem?

Thanks for the explanation, that all makes sense. Rig was purchased new so that's the way it was designed. It's a front living room so the bedroom and bath are in the back on the main floor level. The valve is up high behind the black flush connection. I'll need to do some measuring but it very well could be above the rim.

Also, it would seem that the only way there would be cross contamination is if the black tank hose is left connected, or am I missing something else?